5 Reasons Why Dark Chocolate Is Better than Milk Chocolate
Look good? Forget it, there's way too much sugar. (Photo by .craig)
Showing posts with label macronutrients. Show all posts
Showing posts with label macronutrients. Show all posts
Monday, February 21, 2022
Look good? Forget it, there's way too much sugar. (Photo by .craig)
Sunday, February 6, 2022
How Does Eating Avocados Affect Cholesterol?
Avocados contain plenty of MUFAs, most of which is oleic acid. (Photo by Muffet)
Everyone knows avocados are high in fat, but does that make them healthy or unhealthy? In this post, we'll look at how avocados affect cholesterol levels.
Avocados are technically large berries of the avocado tree, each berry containing a single seed usually called the avocado stone. There are several different cultivars, but on average avocados contain about 15 grams of fat, 9 grams of carbohydrates and 2 grams of protein per 100 grams. Most of the fat (~10 grams) is monounsaturated, while the rest is roughly half saturated and half polyunsaturated.
Most health enthusiasts are either pro-saturated fatty acids (SAs) or pro-polyunsatured fatty acids (PUFAs) – and if you're a long-time reader of this blog, you already know which category I lean towards. Monounsatured fatty acids (MUFAs), however, seem to represent something of a "neutral" group of fats to many. Olive oil, for example, is high in MUFAs, and almost all studies find it either beneficial or at least neutral: generally, LDL decreases and HDL either increases or stays the same.
So if olive oil is good for you, what about avocados? Since both are high in MUFAs, specifically oleic acid, one might expect to see similar results. In rats, adding avocados to their diet seems to increase HDL and decrease triglycerides (link). Avocado leaf extracts appear to be especially effective (link).
Avocados, cholesterol & healthy subjects
Experiments on humans, unfortunately, are not always as unequivocal. The earliest human study I came across find compared an avocado-enriched diet with a diet high in complex carbohydrates and low in fat – namely, the lipid-lowering diet advocated by the American Heart Association (link). The study included 15 women who were randomly assigned to one of the diets for three weeks, followed by 3 weeks on the other diet. Only the avocado diet, on which the women ate between half and one and a half avocados per day, resulted in a statistically significant decrease (~8%) in total cholesterol levels. This was due to a lowering of LDL without affecting HDL, whereas the complex carbohydrate diet lowered HDL levels by ~14%. So much for the heart-healthy effects of low-fat diets.
The second study included 16 healthy volunteers who were fed three different diets for 2 weeks: a high-MUFA diet consisting of 30% fat (75% of which came from avocados), a free diet including avocados, and a low-saturated fat without avocados (link). Both the high-MUFA diet and the low-SA diet reduced total cholesterol and LDL. However, the low-SA diet also also reduced HDL and increased triglycerides, while the other two diets reduced triglycerides. Again, the low-fat diet with an emphasis on limiting saturated fats was the most harmful for cholesterol levels.
I find it somewhat surprising that the free diet with avocados apparently also reduced HDL, even though the authors say the volunteers ate the same amount of avocados as during the high-MUFA diet. Unfortunately I don't have access to the full paper, so I'm not sure what the free diets were like in reality. Perhaps the volunteers simply ate more during the free diet, which could have skewed the results, or maybe the SA/PUFA ratio was significantly lower on the free diet for some reason.
Avocados and people with high cholesterol
Another study included 13 patients with high LDL cholesterol (link). The patients were given a standard vegetarian diet, a vegetarian diet enriched with avocado or a free diet that included avocados. The standard vegetarian diet consisted of 70% carbs, 20% fat and 10% protein, while the vegetarian avocado diet was 60% carbs, 30% fat and 10% protein. The vegetarian avocado diet reduced LDL, whereas the free diet increased it slightly. Only the standard vegetarian diet significantly reduced triglycerides – however, it also reduced HDL more than the other two.
The results of this study seem to contradict the two earlier studies, since simply adding avocados to the diet resulted in slightly lower HDL and slightly higher LDL – in other words, their cholesterol levels worsened. Genetics may play a role here, as some individuals who are predisposed to higher LDL levels seem to react negatively to foods that generally improve the cholesterol ratio. The authors themselves state:
"Low-fat, carbohydrate-rich vegetarian diets may be harmful to hypercholesterolemic patients. The avocado addition to a vegetarian diet does not correct these undesirable effects. To obtain beneficial effects on lipid profile with avocado, lower amounts of carbohydrates and polyunsaturated fatty acids are probably needed."
Yet another study compared the effect of an avocado-enriched diet on healthy subjects and patients with slightly elevated cholesterol levels (link). In healthy participants, total cholesterol decreased by 16% on the avocado diet. In participants with high cholesterol, total cholesterol decreased similarly, with LDL and triglycerides decreasing by 22% and HDL increasing by 11%. The authors conclude that a high-MUFA diet containing avocados improves lipid profile in healthy and especially in mildly hypercholesterolemic people.
Conclusion
Compared to low-fat diets, diets containing moderate to high amounts of monounsaturated fatty acids from avocados seem to result in better cholesterol levels. In healthy people, replacing carbohydrates with avocados generally lowers LDL without affecting HDL, similar to olive oil. In people with high cholesterol, replacing carbohydrates with avocados appears to reduce LDL and, in some cases, increase HDL.
The controversial result is the lower HDL in free diets with avocados. Does simply adding an avocado to your diet actually make cholesterol levels worse? This is a tricky question, since adding an avocado would mean an increase in total energy intake, unless it also means you eat less of something else – which would be the case, unless avocados somehow increase appetite. One possibility is that when the participants added avocados (and thus MUFAs) to their diet, they reduced their consumption of other fatty acids while keeping total energy intake the same. Reducing saturated fatty acid intake could result in lower HDL, although this doesn't necessarily explain the higher LDL. Without knowing what the participants actually ate during their free diet periods, it's difficult to say what the cause is.
While it's generally taken for granted that a) olive oil reduces LDL and has a neutral or positive effect on HDL and b) this effect is due to the high MUFA content of olive oil, there are differences in the food sources of MUFAs. Both avocados and olive oil are high in oleic acid, but olive oil contains squalene, whereas avocados do not. Squalene is a precursor in cholesterol synthesis and is metabolized to cholesterol in the body. Avocados, on the other hand, contain beta-sitosterol, which lowers LDL.
Finally, genes play a major role in cholesterol levels. Apolipoprotein E genotype affects how individuals react to dietary fatty acids and also cholesterol-lowering drugs like statins. Without knowing the genotypes of the participants in the studies, it's hard to say how generalizable the results are.
For more information on diet and cholesterol, see these posts:
Want to Increase Your HDL Cholesterol by 50%? Sage Tea May Be the Answer
High HDL Cholesterol Reduces Risk of Dying in Men
Hibiscus Tea Increases HDL, Lowers LDL and Triglycerides
The Twinkie Diet: Thoughts on Weight Loss and Cholesterol
Tuesday, January 25, 2011
Genes, Diet and Oral Health: Why Do Some People Get Cavities and Others Don't?
As you may know, I have something of an ongoing experiment with dental health. This includes reducing cavities, preventing gingivitis and the receding of gums, and also finding safe ways of whitening teeth.
In previous updates, the main focus has been on the teeth whitening aspect. The last product I purchased was called "Plus White 5 Minute Bleach Whitening Gel". Compared to the supposedly teeth whitening toothpastes out there, this product does seem more effective.
However, in recent months, I've noticed increased sensitivity along the gumline. Specifically, the gums next to two of my upper teeth seem to be the problem. The whitening gel probably has very little to do with it, but it doesn't solve the problem either. In the short term, whitening gels can increase sensitivity, so for the time being, I've turned my focus elsewhere – to preventing caries and improving gum health.
The motivation for this post is that I've struggled with these things my whole life, and despite my various experiments with diet, I've yet to find a proper solution to the problem. When I was a kid, the common explanation was that too much candy and soda was the reason for dental cavities – despite the fact that scientists had already shown that carbohydrates in general give rise to the bacteria that cause caries. So when I got a bit older, I cut back on candy and soda, hoping it would be enough.
Unfortunately, it wasn't. Apart from the Snickers Bars and Coca-Cola I'd occasionally enjoyed that were now gone, my diet remained the same. It took me a long time to discover that all carbs are essentially sugars, that all acidic drinks make the issue worse, and that it's not just Coke and candy that are the problem. You can get cavities just as easily by eating bread and drinking apple juice. Then it was time to get rid of those too.
When I reduced my carb consumption and switched to a more paleo-like diet, my dental health improved, but it still didn't stop me from getting a new cavity every now and then. Furthermore, I knew several people who ate junk food and drank acidic sodas all the time, and yet had never had cavities. Some didn't even brush their teeth every day, let alone floss. When we were kids, my brother and I had very similar diets, and yet I was the only one to get cavities.
These things have led me to believe that genes play a more important part than most dentists would have you believe. Kind of like some people stay thin no matter how much they eat. But, just like in the case of weight loss, your genes do not necessarily determine your fate – it just means you have to know what you're doing. People who don't have the genes for staying naturally thin have to be more careful with what they eat if they want to avoid weight gain. Similarly, people who get cavities easily have to be more careful with dental health.
While keeping your teeth clean by brushing, flossing and chewing gum prevents cavities, I'm wondering whether all the cleaning really strikes the problem at the root (no pun intended). If genetics do play a role, what is it specifically about some people's genes that keeps them from getting cavities, despite their poor dental health habits?
One important factor in cavity formation is saliva. The surfaces of teeth are constantly going through a process of demineralization and remineralization. The balance depends, in part, on salivary flow and the pH of saliva, with the mineral content probably playing a role as well. I know my mouth often feels kind of dry and acidic, which can't be a good thing for remineralization. What is unclear to me is how to affect these things.
There are a million websites out there listing foods that are "acid-forming" or "alkaline-forming", but the classification seems very unscientific. Some list apples as acid-forming because apples themselves are acidic, some list them as alkaline-forming because they claim we should look at what happens after digestion. Here's a quote from one such website:
All foods are "burned" in the body -- more commonly called "digested" -- leaving an ash as the result of the "burning", or the digestion. This food ash can be neutral, acid or alkaline, depending largely on the mineral composition of the foods.
I'm not sure how scientifically valid this theory is in the first place, but I do know that even those who promote the "food ash" theory disagree on which foods leave acid or alkaline ash. One person will tell you plums are acid-forming, while others will tell you they're alkaline-forming. I doubt any of them have actually burned plums and studied the ashes.
So, expect some dental health related posts in the upcoming weeks and months, as I go through some of the papers on the subject. I'm also interested in hearing your comments, especially if you've previously suffered from cavities but managed to find a solution.
Meanwhile, for more information on dental health, see these posts:
Tea, Coffee and Cocoa: All Good for Your Teeth
Dental Health Effects of Green and Black Tea
The Role of Coenzyme Q10 in Oral Health
Whitening Teeth & Healing Gums: In Search of the Perfect Toothpaste
Read More......
Thursday, November 11, 2010
The Twinkie Diet: Thoughts on Weight Loss and Cholesterol
A few days ago, CNN reported on a nutrition professor who lost 27 pounds in ten weeks eating mostly Twinkies (link). Not only that, but health markers improved too – LDL went down and HDL went up.
Some people seem to think the results resolve the old question of whether calories are all that matter in weight loss. After all, if you can lose weight by eating Twinkies, Doritos and Oreos, what else could it be than calories? Surely that's just about the worse diet you can have.
While I'm obviously a big fan of self-experimentation, I think the results have been misrepresented in some cases. What do I mean by that? Let's look at the experiment and the results a bit more closely. Here's a quote from the article:
For a class project, Haub limited himself to less than 1,800 calories a day. A man of Haub's pre-dieting size usually consumes about 2,600 calories daily. So he followed a basic principle of weight loss: He consumed significantly fewer calories than he burned.
If we take the 2,600 calories daily as the correct figure, then for the ten weeks, Haub was running an 800 calorie deficit. It's hardly surprising that he lost weight. When you cut back enough on your energy intake, you start losing weight – in this sense, a calorie is a calorie.
But since this is an experiment with only one participant, it's impossible to say whether more or less weight would have been lost if the diet had been different. Did all the sugar he was eating prevent him from losing the maximum amount of body fat? There's no way to tell.
There are some hints, however, that it's not all about calories. The amount of calories consumed may be the primary factor in how much weight or fat is lost, but that doesn't rule out other factors. In rats, for example, green tea increases weight loss during calorie restriction. The rats consuming green tea burned more of their body fat and absorbed less fat from the diet, despite eating the same amount of calories.
In real life settings, the argument that a calorie is a calorie is difficult to examine, because the number of calories we burn is not constant – it depends on many variables. We now know, for instance, that genetics play a role. Some people have a hard time putting on weight, because the more they eat, the more calories they burn. They may get an urge to exercise more, for example. And anyone who's tried different diets knows that some foods make you more energetic than others, despite having a similar number of calories.
But that's not all. Some people don't put on weight even when exercise is forbidden. Their bodies just start using all that excess energy in other ways: increasing metabolic rate, heat production, etc. Is a calorie really a calorie in this case?
Then there's the question of how to count the absorption of calories from different macronutrients. If you divide people into two groups and feed both the same amount of calories, but have one group eating more protein and the other group eating more carbohydrates, their weights will be different. In general, high-protein diets result in more weight loss than high-carbohydrate diets.
As you can see, the question is hardly as simple as some people make it out to be. And there are more similar things that complicate the issue. Stephan from Whole Health Source has a good post on the Twinkie diet and how it relates to hormones and fat mass regulation, and I'm sure there are other health bloggers who have picked up on the same article.
Putting the calorie issue aside, perhaps the thing that aroused the most interest was the part about improved biomarkers. Sure, you can lose weight eating a terrible diet, as long as your eating very little, but shouldn't that wreck your health in other ways? Apparently not:
Haub's "bad" cholesterol, or LDL, dropped 20 percent and his "good" cholesterol, or HDL, increased by 20 percent. He reduced the level of triglycerides, which are a form of fat, by 39 percent.
But that's not really big news. You see similar things happening in many studies where the participants are put on weight loss diets, regardless of what the diets are like. Even in the studies where overweight people are put on the conventional low-fat, high-carb diet – which is not really a good approach for improving cholesterol levels, glucose and insulin – these health markers improve while they're losing weight. As a spokeswoman for the American Dietetic Association says in the article:
"When you lose weight, regardless of how you're doing it -- even if it's with packaged foods, generally you will see these markers improve when weight loss has improved," she said.
However, as in the case of the amount of weight lost, there's really no way to tell based on this experiment whether his health markers would have changed differently on another diet with the same calories. Low-carb and low-fat diets have very different effects on cholesterol during a calorie deficit, for example (note also how the subjects lost more weight during the low-carb diet despite eating more).
Since the study only lasted for ten weeks, the fact that his LDL and triglycerides decreased while HDL increased doesn't say much about the long-term effects. I wonder what his cholesterol levels would have been after a year of following the Twinkie diet.
Also, there's more to cholesterol than just LDL, HDL and triglycerides. In the case of lipoprotein particles, size matters. A diet consisting mostly of sugary snacks is probably not going to do a whole lot of good for LDL particle sizes in the long run. And even when HDL and LDL levels look good on the surface, there's oxidized LDL and lipoprotein (a) to worry about.
What we can say with some certainty is that regardless of how you do it, returning to a normal weight seems healthier than being obese. In the maintenance phase, which lasts much longer, more things should probably be taken into consideration. Haub himself seems to have mixed feelings about his experiment:
"I wish I could say the outcomes are unhealthy. I wish I could say it's healthy. I'm not confident enough in doing that. That frustrates a lot of people. One side says it's irresponsible. It is unhealthy, but the data doesn't say that."
While the health markers are interesting, it would have been interesting to hear more about his experience in general. How did he feel before, during and after the diet? Was he feeling energetic or tired? How was his mood? Did he have any problems, digestion, bad skin, etc?
Before you kickstart your own Twinkie diet, note that professor Haub also had a multivitamin and a protein shake daily, which may have influenced the results somewhat. And if you've already tried a strange diet and managed to lose weight, drop a comment and tell us how it went.
For more information on diets and weight loss, see these posts:
Alternate-Day Feeding and Weight Loss: Is It the Calories Or the Fasting?
A Year of Intermittent Fasting: ADF, Condensed Eating Window, Weight Loss, And More
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
Green Tea Extract Increases Insulin Sensitivity & Fat Burning during Exercise
Read More......
Friday, July 30, 2010
What a "Heart-Healthy" Diet Does to Your Cholesterol Levels
What happens when you follow the American Heart Association's dietary recommendations? You know, a diet high in whole grain, vegetables, fruit and berries, but low in animal protein and fat, especially that nasty artery-clogging saturated fat.
According to conventional wisdom, you will be healthier in general. In particular, your cholesterol levels are supposed to improve – though it's never quite clear what "improvement" here means. Is it lower total cholesterol? Or perhaps lower LDL and higher HDL? And what about triglycerides and oxidized LDL?
Fortunately, a few years ago the Journal of the American Heart Association published a study that looked at what happens to cholesterol levels while on the officially heart-healthy diet (link). In contrast to many other studies, the participants in this one were healthy and had normal cholesterol levels to begin with. The idea was to see whether adopting an optimal diet would make them even healthier.
Study design and composition of diets
The study included 37 healthy women and consisted of two phases. During the first phase, the women followed a low-fat, low-vegetable diet for five weeks. After that, there was a three week washout period, followed by the second experimental diet. This second diet was the "optimal" diet, which was also low-fat but this time included lots of vegetables, fruit and berries. To make sure that the dietary guidelines were followed, the meals were supervised.
Both diets included 8 portions of grain products, 3-4 portions of low-fat or fat-free dairy products, and 2 portions of lean meat, chicken or fish. In the first phase, the subjects were given 2 portions of fruit and vegetables per day. In the second phase, the amount of fruit and vegetables was increased to 4-5 and 5-6 portions, respectively.
Dietary fats were replaced vegetable oils and spreads which contained minimal amounts of trans fats. The amount of total fat and saturated fat decreased, whereas the amount of polyunsaturated fats increased. To replace the lost calories, the subjects ate more carbohydrates and protein. Fiber intake also increased; in the second phase, it was nearly twice as much as at baseline.
Thus, both diets were very close to official recommendations: they included only moderate amounts of fat and animal protein, the fat was mostly from vegetable oils high in polyunsaturated fatty acids, dairy products were low in fat or fat-free, and grain products high in fiber were included. In addition, the second phase was high in veggies, fruits and berries.
HDL, LDL and triglycerides
After the low-fat, low-vegetable phase, total cholesterol was unchanged. On the other hand, triglycerides and HDL decreased, while LDL levels increased. The increase in LDL was apparently not statistically significant, which is probably due to the small sample size.
When the amount of vegetables, fruit and berries was increased, total cholesterol decreased. Triglycerides remained the same, but both HDL and LDL decreased:
Thus, reducing the amount of fat in the diet and replacing animal fats with vegetable oils did not change total cholesterol but did change the cholesterol profile: HDL and triglycerides decreased, while LDL increased. From the "good cholesterol, bad cholesterol" standpoint, adopting a low-fat diet actually changed things for the worse.
Things were not much better when vegetables, fruit and berries were added to the low-fat diet. Total cholesterol was clearly reduced, which by some standards is admittedly a positive change. Importantly, however, this change was not achieved through a decrease in "harmful" LDL but in "healthy" HDL.
The amount of triglycerides did decrease compared to baseline, but the reason is unclear. Generally, replacing fats with carbohydrates seems to increase triglycerides. Also, triglycerides decreased after the first phase, when the diet was low in vegetables, and did not decrease further after the second phase, so dietary antioxidants don't seem to be the explanation either. One thing that comes to mind is alcohol intake, which is not reported in the study. Perhaps the subjects reduced their alcohol intake while on the experimental diets? That would show up as a lower triglyceride score, but we can't know for sure.
Oxidized LDL and lipoprotein (a)
Both oxidized LDL and lipoprotein (a) are independently associated with a higher risk of atherosclerosis – more so than total cholesterol or LDL. In fact, oxidized LDL (ox-LDL) is believed to cause clogging of arteries and inflammation. Lipoprotein (a), also called Lp(a), is a known risk factor in many cardiovascular diseases, although its function is not entirely understood.
The most interesting result of the study is that the number of oxidized LDL particles and Lp(a) increased significantly as a result of following the low-fat diets. Oxidized LDL increased by a whopping 27% in the first phase. Even after vegetables, fruits and berries were added to the diet, ox-LDL levels were still 19% higher than at baseline. Similarly, Lipoprotein (a) was 7% higher after the first phase and 9% higher after the second phase compared to baseline.
What this means is that two important risk factors of atherosclerosis worsened markedly after following the very dietary recommendations that are supposed to reduce risk of atherosclerosis. Although plasma antioxidant capacity correlated with the intake of fruit, vegetables and berries, the antioxidants in them were clearly not enough to protect from these harmful changes.
The changes in total cholesterol, HDL, LDL and triglycerides were relatively small, which may be partly due to the short duration of the study. However, the 27% increase in ox-LDL demonstrates that diet can have a dramatic even in a short period of time.
Conclusion
The authors describe the results as "unexpected". According to them, a decreased intake of fat – especially saturated fat – should have led to a decrease in risk factors. They quote a number of studies where replacing saturated fatty acids with polyunsaturated fatty acids led to a "beneficial" decrease in total cholesterol. So why did the risk factors of atherosclerosis not see a similar "beneficial" change?
It is true that fats and oils high in polyunsaturated fatty acids generally tend to lower cholesterol (although the relationship between different fatty acids and cholesterol is more complicated than that). A completely different question is whether total cholesterol even matters, however. Even official recommendations acknowledge that the ratio of LDL to HDL is a better predictor of CVD than total cholesterol.
As was to be expected, the low-fat diets in this study did reduce total cholesterol. But if that decrease happens by reducing HDL and not changing or even increasing LDL, is the change really for the better? Most importantly, if the drop in total cholesterol comes with a marked increase in Lp(a) and oxidized LDL, can the results really be seen as beneficial?
Since the results of the study are incompatible with the cholesterol hypothesis and dietary recommendations, the authors came up with an alternative explanation. According to their hypothesis, high Lp(a) and ox-LDL may in fact be a sign of existing artherial damage being fixed and therefore a positive thing – but of course only in the case of low-fat diets. Right.
For anybody who has been keeping up with the gradual destruction of the cholesterol hypothesis, these results are not all that surprising. For example, we already know that polyunsaturated fatty acids oxidize much more easily than monounsaturated or saturated fats. It seems logical that LDL would be oxidized also.
What is somewhat surprising, however, is that the study was published in a journal that promotes the official dietary recommendations as heart-healthy.
For more information on cholesterol and diets, see these posts:
Which Oils and Fats Are Best for Cooking?
Carotenoids and Lipid Peroxidation: Can Vegetables & Fruit Reduce ALEs?
Sugar and AGEs: Fructose Is 10 Times Worse than Glucose
Anthocyanins from Berries Increase HDL and Lower LDL
Read More......
Wednesday, May 19, 2010
My Current Health Regimen v2.0
This is my updated health regimen, aimed at adding a significant number of healthy years to my expected lifespan. As it's subject to change, I will keep this post updated accordingly. Major revisions (such as v2.0) will appear once a year or so; minor changes (such as v2.1) will be made as needed. With every major revision, I will move the post from the archives to the front page.
Since a long, healthy life is preferable to a short life by most people, following the regimen would make sense even without considering technological innovations. The true goal of my regimen, however, is to stay alive long enough to see rejuvenation therapies become a reality. In the long run, each year that I'm able to add to my expected lifespan now through things like dietary changes, exercise, and supplements, may grant me several extra years in the future.
Therefore, even those lifestyle changes that require considerable effort and resources while offering a seemingly limited benefit, make sense if one looks at the big picture. For a chance to see the world in 2090, I'm willing to skip the cheeseburger today.
My health regimen consists of four categories: diet, supplements, physical exercise, and brain health. All of the items under each category have some kind of scientific basis, and in contrast to my ongoing experiments, will remain a part of the regimen for the time being. Therefore, my current experiments are not a part of my long-term health regimen – unless they prove to be beneficial, in which case they'll be moved from ongoing experiments to the regimen.
Main changes from v1.0: none.
Avoiding harmful foods
The most important part of my diet is avoiding unhealthy things; increasing the intake of healthy things only comes in second. This is because preventing damage from happening in the first place is easier than repairing it later on.
I consider the worst culprit of modern diets to be an emphasis on grain products, fructose, and polyunsaturated fatty acids. There's considerable evidence to suggest that most people would do much better without them. Hence, things like pasta, rice, bread, candy, fruit juices, and most vegetable oils are off the daily menu. I only eat them rarely, and then simply because they taste good. For the past few months, I've allowed myself to eat whatever I want once a week (usually foods like pizza or fresh bread), which seems to be working well.
I originally cut back on my fruit intake, which used to be quite high some years ago, because I learned that fructose increases triglycerides especially in men, and fructose is not handled very well by the body in general. I later learned that fructose also forms AGEs much more rapidly than glucose, which kept me from reintroducing most fruits to my diet and eat berries instead, since they contain more nutrients per fructose calorie. However, I've now increased even my fruit intake a little, having read more about the AGE-inhibiting effects of phytonutrients found in fruit. I will expand on this later, but for an example of what I'm talking about, see my post about carotenoids inhibiting lipid peroxidation.
While much of this fits well with paleo dieting, I also diverge from the paleo diet these days. You may or may not remember that I used to be a potato hater back in the day, both because they could not be eaten raw (making them anti-paleolithic) and because of their high carb content. Basically, potatoes are just empty calories. But once you have your insulin sensitivity and blood glucose under control, I don't think a few potatoes now and then is much of a concern. At least they're low in fructose.
As you may recall, I followed a low-carb diet for the past year with an emphasis on paleo foods. I got on the low-carb, high-fat wagon in the first place to prove that eating a diet high in fat does not make you fat – and it didn't. However, this diet combined with my year-long intermittent fasting experiment resulted in a moderate-to-high intake of protein, the longevity effect of which I'm now questioning. To lower my protein intake slightly means eating either more fat or more carbohydrates, and since my fat intake is already very high, I've reintroduced some carbs into my diet. That is, I now occasionally eat potatoes not because I think they are necessary for health, but because they are low in protein. More on protein and longevity in future posts.
I still don't make nuts a dietary staple, because of their poor omega-3/omega-6 ratio and because I like to keep my PUFA intake low. That is, I aim not only for a good ratio of omega-3 and omega-6 fatty acids, I try not to eat too much of them in general. Omega-3 is particularly prone to undergo lipid peroxidation, and while nuts probably have micronutrients that protect them from oxidation to some degree, I'm playing it safe until I learn more.
Main changes from v1.0: slightly increased carb intake, slightly decreased protein intake, slightly decreased polyunsaturated fatty acid intake.
Eating healthy foods
Despite eating some more carbs these days, my diet is still fairly low in carbohydrates. My daily intake used to be around 100 grams; I have not measured my current intake, but I suspect it's around 100-150 grams these days. My main protein sources used to be meat, fish and eggs, but during the past year I've cut back on eating eggs because of their high methionine content. I'm still figuring out whether methionine restriction makes sense in humans, but in the meantime I limit my egg intake to 3-4 eggs a week.
Sources of fat, in the order of importance, are olive oil, palm oil, butter, cocoa butter, coconut milk, ghee, coconut oil, and sesame oil. Olive oil tops the list because I love the taste and because it's high in MUFAs but low in PUFAs and consistently does well in just about every health study. There may not be anything magical about MUFAs per se, but even if it's the polyphenols in olive oil that are behind all the positive health effects, olive oil still seems like a good choice. Palm oil is there because it's rich in tocotrienols (at least compared to other natural foods), low in PUFAs and high in SAs (making it suitable for heating), and because I've grown to like the taste.
Lard is off the menu for now because I ran out. Heavy cream has been replaced by coconut milk, partly because of dairy products increasing IGF-1, which may be bad for longevity (more on that in future posts). I don't eat cocoa butter raw (although I could, it's delicious), but I get plenty from all the dark chocolate I eat. Somebody asked me in the comment section why I eat sesame oil since it contains quite a bit of PUFAs, and noticing this was indeed so, I was going to remove it from my diet altogether. However, doing some reading I found that sesame oil seems to reduce markers of lipid peroxidation, so I kept it on the menu. I just use it for taste, however, so my intake of sesame oil is very low anyway.
Depending on my daily menu, anywhere between 50 to 70% of my total calorie intake is from fat. My daily menu has changed a bit, but percentage of fat is still the same. Most of this is saturated fat, which has been given a bad rep for reasons I believe are incorrect. I began reducing grain products and increasing my saturated fat intake years ago, and it hasn't killed me yet. In fact, my HDL has increased and my LDL has decreased on this diet. Triglycerides are not bad but could be better – a testament to my main vices, beer and wine.
There is one cereal grain I regularly eat, however: rolled oats. They're a convenient source of beta-glucan, which appears to be good for cholesterol and avoiding heart disease, and they don't contain gluten. Oats also contain quite a bit of quality protein. I used to eat them with milk and berries, but then switched to a combination of heavy cream and water to reduce my consumption of lactose and galactose (which easily form advanced glycation endproducts, AGEs). Now, I've stopped adding even heavy cream, because milk protein seems to interfact with the polyphenols in berries. So it's a mixture of coconut milk and water nowadays – not as good as cold milk, but still pretty good.
As for red meat, despite how it's portrayed in the media these days, I'm not convinced that meat consumption is harmful. Indeed, a recent review supports the hypothesis that processed meat, not meat in itself, may be harmful. The biggest problem I used to see with meat is the generation of AGEs. Though there is disagreement just how harmful consuming AGEs with food are, I tried to minimize the potential damage by avoiding overcooking and taking supplements. I no longer think AGEs in meat are a huge problem, however – more on this later. The reason I don't eat huge portions of meat like I used to is because of the high protein content.
And finally, the beverage department. I still love my daily coffee, which I drink 1-2 cups per day. Coffee has some nice health benefits too. Green tea is obviously staying on the menu; the studies showing positive health effects just keep on piling up. All in all, beer doesn't really belong to the "eating healthy foods" category, but even beer does contain some good stuff.
As you may recall, I used to drink yerba mate with meals to reduce the formation of AGEs. It's since come to my attention that yerba mate is carcinogenic at higher doses, so I now drink it only rarely. Green tea or black tea are safer bets, despite somewhat contradictory results in reducing AGEs and ALEs.
Main changes from v1.0: decreased egg intake, changes in the use of fats and oils, reduced yerba mate consumption, avoidance of lipid peroxidation.
A note on diet tweaking
It's much easier to point out things that are wrong in various foods than it is to prove something is healthy. These days, I'm more wary of advertising my diet as the best choice for everyone than I was before. Part of the reason is that the more I read and learn about nutrition, the more complicated everything becomes.
Case in point: I used to tell people vegetables are bad because, as an evolutionary strategy, they produce toxins to protect them from being eaten (which is true). Now, having learned of the importance of hormesis, I think vegetables are good because of those same toxins! I was also a huge fan of eating fruit (especially organic fruit) at one point, because it seemed to make sense from an evolutionary point of view. The, I got a little skeptical towards them because of their fructose content. Now, I think the benefits may outweigh the negatives.
All this, however, doesn't stop me from wanting to find the optimal diet for longevity. On the contrary, it's a healthy reminder not to get too emotionally attached to my health regimen, and to be ready to admit mistakes and make alterations as I learn more.
Going without food
The third key component of my diet used to be intermittent fasting. I stated in the first version of this post that "I may change my mind in the future, but for now I expect periodic food deprivation to remain in the regimen." That is still true to some degree: I no longer do a 24/24 hour cycle of fasting and eating, but I don't make it a point to eat three meals with snacks a day either. I often skip breakfast and lunch and eat only dinner.
The thing that lured me to try intermittent fasting was that there are studies suggesting that all or most of the benefits of chronic calorie reduction can be had by alternating zero calories with double the normal calories every 24 hours. While I no longer believe that IF is equivalent to CR, I do think that fasting in general is beneficial. An improved insulin sensitivity is a known result of intermittent fasting. Insulin sensitivity is associated with longevity, and among supercentenarians, insulin sensitivity is common.
Perhaps a more interesting thing about fasting is that it increases autophagy, a process in which the cell consumes a part of itself for energy. This can happen during ordinary cell maintenance, or when the body is deprived of nutrients. Since improved autophagy is at least in part why caloric restriction works, this makes other, less demanding forms of nutrient deprivation attractive options.
The reason I stopped doing strict IF is because I don't think there is much evidence that fasting for 24 hours and then eating for 24 hours is somehow optimal in itself. Most importantly, IF does not extend lifespan in most studies. Why IF is not equivalent to CR is not clear, but recent studies suggest protein may have a lot to do with it. My intermittent fasting diet resulted in huge meals with lots of protein, and I now suspect that this may have diminished much of the potential benefits.
Main changes from v1.0: no more 24/24 intermittent fasting, no more huge protein-heavy meals.
Supplements
The most important supplement in my regimen is vitamin D3. Most people are deficient in vitamin D, and the health benefits are so overwhelming that if there's one supplement I would recommend spending money on, it's vitamin D3. I usually take 5,000 IU of vitamin D3 daily, and at last check, my levels were at 45 ng/mL, which is in the optimal range. Now that it's summer, I'm taking 2,500 IU daily. I know some people take the same amount all year round, but since I do spend some time in the sun, I don't want to overdo it.
One of the supplements that has remained in the regimen since last time is vitamin K2, which is sort of a newcomer in the supplement scene but nonetheless has some impressive studies behind it. I'll write more about it in the future, but here's one study of interest for men: dietary vitamin K2 may reduce prostate cancer. Since fermented dairy products, which I'm not sure are the best choice for health otherwise, are the best dietary source of vitamin K2, I'm taking supplements instead. At the moment, I take 90 mcg of MK-7 (Jarrow MK-7) and 5 mg of MK-4 (Carlson Labs Vitamin K2) every third day in an attempt to find a balance between affordability and the long serum half-life of vitamin K2.
I used to take a tablespoon of fish liver oil daily, because it has lots of omega-3 fatty acids in bioavailable form (EPA and DHA) and almost no omega-6 fatty acids. A higher dietary ratio of omega-3 to omega-6 seems to be very beneficial in general, and fish oil has been shown to decrease inflammation. A commonly quoted optimal ratio is between 1:1 and 1:4, which seems to be close to how our paleolithic ancestors ate. As part of my plan to avoid excess PUFAs, I've dropped fish liver oil from the menu. I'm currently in the process of weighing the pros and the cons; it may be that a tablespoon per day will prove to be worth it in the end.
I also used to take resveratrol with quercetin during fasts to increase autophagy. I would still continue to take them, but unfortunately I can't afford all the supplements I might like to take (including AOR Ortho-Core, which is off the list for the time being), so I take resveratrol only occasionally. Meanwhile, I'm on the lookout for other things that increase autophagy. Curcumin is a cheap alternative, and it has other health benefits too, which is why I add turmeric to most of my foods.
Since my damn blender keeps leaking from the bottom, I'm no longer making smoothies every day like I used to. So these days I just add some ground flax seeds to my rolled oats for the flax lignans. Flax lignans may prevent hair loss, among other health benefits. Some people prefer to take them in supplement form, but flaxmeal is a cheaper and equally effective way to consume flax lignans. For best effects, they should be consumed twice a day with ~12 hours in between. Other things I do to prevent hair loss is use shampoos with ketoconazole and piroctone olamine.
Main changes from v1.0: no more fish liver oil, some supplement cutbacks due to costs, increased curcumin intake.
Exercise
My exercise routine is probably the weakest part of my regimen, compared to how much effort I put into diet and supplements. In the summer, I run for 30-45 minutes once a week to get some aerobic exercise (I should start again, since summer is here!) The goal is to keep the heart and lungs healthy, reduce blood pressure, and improve mood. In the winter, when it gets too cold for running outside, I go to the gym for strength training instead. Strength training reduces the risk of injury, prevents osteoporosis, supports joint health, and prevents muscle loss resulting from aging.
I also practice martial arts, which combines aerobic and strength training, to a degree. The main reason for me, however, is that it provides me with a basic set of self-defense skills and improves coordination. With aging, there is usually an increased fear of falling and hurting oneself – something children naturally don't have. Getting thrown around every week is a way to maintain a healthier attitude towards my body and prevent an irrational fear of getting hurt. I want my mind to rule over my body, not the other way around.
Main changes from v1.0: none.
Brain training
Any anti-aging regime should also take into account the importance of maintaining mental health. It doesn't take a genius to see that people who use their brains actively retain their cognitive abilities far longer than those who are passive.
One of the ways I keep the rational side of my brain fit is reading scientific papers and writing about them on this blog. I like logical problems in general, and I think practicing problem-solving skills are important for everyone, whether it's through work or hobbies. To train the creative side, I do things like play instruments, compose music, and read and write fiction.
My biggest problem is and always has been rather poor short-term memory. I don't know whether it's because my mind is always occupied with a zillion things, but it's more than once that I've gone to the grocery store to buy something I need and come back with something else entirely. This kind of absent-mindedness seems to run in the family. I believe it can be improved through training, however. The memory game experiment intends to increase IQ, but it improves short-term memory as well (I've pretty much forgotten about this experiment lately, by the way – I'll have to start playing again!)
Main changes from v1.0: none.
Quick summary of the health regimen
As a part of my diet, I regularly eat the following foods:
- Meat, fish
- Olive oil, palm oil
- Butter
- Vegetables, berries, fruit, oats, dark chocolate, coconut milk
- Coffee, tea, wine, beer
I limit or avoid eating the following foods:
- Grain products like pasta, bread, and rice
- Fruit juices, candy
- Vegetable oils high in PUFAs
In general, my diet is high in fat and lowish in carbohydrates. I consume saturated fat and monounsaturated fat liberally but limit polyunsaturated fats.
My supplement regime consists of the following:
- Vitamin D3: 2,500-5,000 IU daily
- Vitamin K2: 90 mcg of MK-7 and 5 mg of MK-4 every third day
- Varying amounts of green tea daily
- Flax lignans: 1-2 tablespoons of ground flax seeds daily
My physical health regime consists of martial arts, running (in the summer), and strength training (in the winter). For mental health, I do things that train the creative and logical sides of the brain.
For more information on anti-aging methods and living longer, see these posts:
Anti-Aging in the Media: New York Times on Caloric Restriction and Resveratrol
How to Live Forever: My 5 Steps to Immortality
L-Carnitine, Acetyl-L-Carnitine and Cognitive Function in Humans
Caloric Restriction Improves Memory in the Elderly
Read More......
Wednesday, November 18, 2009
Alternate-Day Feeding and Weight Loss: Is It the Calories Or the Fasting?
I don't know if you noticed, but a new study on intermittent fasting recently made headlines in several media. The paper basically found that alternate-day fasting (or "on-off fasting" as it was named in some articles) helped obese adults to lose weight.
That's not a huge surprise, really. If you're obese, it means you eat too much of the wrong foods and probably too often. Fasting every other day means you'll at least be eating them less often, if not less per se. However, the conclusions that have been drawn in various articles from the study seemed a little suspicious to me, so I decided to read the whole paper.
Indeed, the authors themselves appear to be somewhat confused as to what really caused the weight loss. So without further due, let's take a closer look at what the study actually found (link).
Study design
12 obese women and 4 obese men were recruited for the study. Mean age was 46 years, mean body weight was 96.8 kg, and mean BMI 33.8. Not exactly the featherweight league.
The study consisted of three phases. The first one was a 2-week control phase, during which the subjects were told to maintain their usual weight by eating and exercising as they normally would. In the second phase, which lasted for 4 weeks, all participants were given a standard menu containing 25% of their baseline energy needs on the fast days. On the feeding days they could eat as much as they wanted. The third phase, also 4 weeks, was similar to the second one. The only difference was that the participants could choose what they wanted to eat on their fasting days, as long as they only ate 25% of their baseline needs.
So, the first thing that sets this study apart from how most people do intermittent fasting is that they didn't consume zero calories during their fast. They just ate significantly less. The second thing is that the fasts began and ended at midnight. Most people (including me) start and end their fast sometime during the day, because it allows them to eat at least once a day. If the participants went to sleep before midnight, their "fasts" were significantly longer than 24 hours.
Their standard diets were also less than optimal in my opinion. Things like chicken fettucini, vegetarian pizza, chicken enchilada, cookies, and crackers aren't exactly paleolithic foods consistent with the idea of intermittent fasting. But then, this wasn't a paleo study, which explains why they were fed high-carb, low-fat foods. For the third phase, they were given diet tips by a registered dietitian:
On the ad libitum food intake day, subjects were instructed to limit fat intake to <30%> dairy options.
So more carbs and less fat once again. They probably took some of this advice and applied for their feeding days as well, which makes me wonder if they wouldn't have lost even more weight had they opted for low-carb foods instead. Still, as you can see from the results below, they did manage to lose weight even with this diet.
Results
During the first phase, there was no weight loss. This is unsurprising, since all the participants just kept on eating whatever made them obese in the first place. During the eight weeks of alternate-day fasting they did lose weight, however.
In the second and third phase the subjects lost weight at a rate of ~0.7 kg per week. At the end of the study, they had lost about 5.6 kg, most of which was fat. Mean BMI decreased from 33.7 to 29.9, while body fat percentage dropped from ~45 to ~42%.
Cholesterol levels were also reduced as a result of alternate-day fasting. HDL remained the same, but LDL decreased by almost 25%. This to me is a more impressive result than the weight loss, which I think could've been greater with proper food choices.
Systolic blood pressure was lowered by 4.4 mm Hg, but diastolic blood pressure remained the same. Heart rates varied throughout the study, but at the end, they were about 4 beats per minute lower than in the beginning.
Discussion
Okay, so everyone lost some weight and improved their LDL/HDL ratio on this modified version of intermittent fasting. But what exactly is behind these results? The first thing that came to my mind as I was reading the paper was: how much were these people eating on their feeding days? Surely that would have a drastic effect on weight loss.
Unfortunately, there's no mention of this in the paper. Yes, they were told they could eat ad libitum, but apparently they were not told to keep a record of what or how much calories they ate when they were not fasting. I know food diaries are generally unreliable (people tend to underestimate how much they eat), but it would've been better than nothing. The authors seem surprised that the subjects lost as much weight as they did:
We predicted that subjects would lose a total of 4.5 kg fat mass after 8 wk (on the basis of a 75% decrease in energy intake on the fast day, with no change in energy intake on the feed day). The actual fat mass lost (5.4 kg) exceeded our predictions.
With no change in energy intake on the feed day? I'm not sure where the authors got the idea that when you eat very little on one day, the next day you won't be extra hungry and compensate. That's certainly not my experience. On the contrary, I fully compensate for any missed calories by just eating twice as much the next day. Certainly not compensating can be done if one wants to, which may be what happened here:
This indicates that these subjects were also limiting their energy intake on the feed day, which may have occurred because the subjects knew they were enrolled in a weight loss trial.
On the other hand, some articles in the media (such as this one) have reported that there was a slight compensation going on:
On non-fasting days people typically ate between 100 percent or 125 percent of their calorie needs.
This statement is probably from a press release by the authors, but the paper itself is silent on the issue. In any case, if you're eating 75% less on one day and only 25% more the next, you're still 50% short.
That, in effect, makes this a study on caloric restriction, not intermittent fasting. How is it surprising in any way that people who eat half (or even less) than what they're used to manage to lose weight? Isn't that obvious? The amount of weight they lost is pretty much what you'd expect on a low-fat, calorie-restricted diet. And based on other studies, if they'd eaten more calories but restricted carbohydrates, they'd have lost more weight.
The whole point of intermittent fasting is that you don't have to restrict your energy intake, you just don't eat all the time. If energy intake is the same and yet there are health benefits, then we can conclude that it's the fasting that is behind them. If, at the same time, calorie intake is restricted, there's no way of knowing whether it's the reduced calories or the fasting that is the cause. And of course, if intermittent fasting leads to a voluntary reduction in energy intake, that tells us something too.
I have a feeling that eating the small meal every other day magically resulted in no hunger in this study. They were probably consciously limiting their food intake even though they were told they could eat as much as they want. The fact that the authors actually expected the participants to eat only their usual calories on feeding days makes me even more suspicious.
Try eating 500 kcal on one day and then seeing how you feel the next day. If you typically eat 2,000 kcal, somehow I don't think 2,500 kcal is going to cut it. I know it doesn't for me, at least not in the long term. As for this diet being much easier to follow than old-school calorie restriction (which the paper seems to suggest), I doubt it.
For more information on intermittent fasting and caloric restriction, see these posts:
Intermittent Fasting: Understanding the Hunger Cycle
Slowing Down Aging with Intermittent Protein Restriction
Caloric Restriction Improves Memory in the Elderly
Intermittent Fasting Reduces Mitochondrial Damage and Lymphoma Incidence in Aged Mice
Read More......
Wednesday, September 23, 2009
Should Saturated Fat Be Avoided in Low-Carb Diets?
Browsing through older issues of Nutrition & Metabolism, I came across an interesting article on saturated fats. It's a commentary to another article, titled "The case for low carbohydrate diets in diabetes management" (link). In the original paper, the authors argue that low-carb diets are better than traditional low-fat, high-carbohydrate diets for weight loss, blood pressure, metabolic syndrome and dyslipidemia. They also note that low-carb diets reduce triglycerides and increase HDL.
However, the authors are skeptical of the popular Atkins diet, because of its potentially high saturated fat content. Their recommendation is to limit saturated fat consumption and to use monounsaturated and polyunsaturated fats instead. So, while they succesfully dispel common myths about low-carb diets, they still propagate the myths about saturated fat being detrimental to health.
The authors behind the commentary, Volek and Forsythe, go over several myths about saturated fat and cholesterol (link). While they commend the authors of the first paper on their observations on low-carb diets in general, they note that restricting saturated fat is unnecessary.
The reason is that much of the bad reputation of saturated fat comes from overgeneralizations and misinterpretations of the data. To make a statement like "saturated fat is bad for you" doesn't really tell us much. Even if we narrow it down to saturated fat being bad for cholesterol, it still just leaves us with more questions.
Is all saturated fat bad or just some? Does the amount of saturated fat matter? Do combinations of different saturated fats behave differently than single saturated fats? And importantly, what does "bad for cholesterol" mean exactly – does it increase total cholesterol, increase LDL, decrease HDL, or something else entirely?
While the commentary doesn't answer every possible question on saturated fat and cholesterol, it does shed light on some of these questions. Since I was so inspired by this article, I've also referenced quite a few related studies not mentioned in the commentary.
First, there are different types of saturated fat. One way of categorizing fats is according to their carbon chain length, and this factor plays a part in how fats affect cholesterol levels. For example, stearic acid, which has an 18-carbon-chain (C18) and is found especially in meat and cocoa butter, does not raise cholesterol levels (link). Palmitic acid (C16) and myristic acid (C14) seems to raise cholesterol the most (link, link). Depending on the study, the cholesterol-raising effect of lauric acid (C12) is either slightly lower (link) or higher than that of palmitic acid (link). Clearly, saying that all saturated fats behave the same way is an oversimplification.
Second, the dietary context in which saturated fat is consumed plays a crucial part. Nobody eats only saturated fat. The lipid profile will depend not only on the amount of saturated fat, but also on the ratio of protein, fat and carbohydrates. Replacing carbohydrates with any fat will lower fasting triglycerides, and replacing carbs with saturated fat also raises both HDL and LDL (link). When total fat intake is relatively low, increased saturated fat intake is associated with less progression of atherosclerosis (link). Interestingly, the same study also showed that when replacing carbohydrates or protein, polyunsaturated fats were not associated with progression of atherosclerosis, but when they replaced other fats, they were.
In addition, it might makes a difference which other fatty acids are consumed with saturated fats. For example, when palmitic acid is consumed with linoleic acid (an unsaturated omega-6 fatty acid), it ceases to increase cholesterol levels (link). When dietary olive oil is replaced with palm oil, which is high in palmitic acid, no change in cholesterol is seen (link), possibly because other fatty acids are also present in the average diet.
The form in which the saturated fatty acid comes is also important. In a synthetic form, myristic acid raises total cholesterol less than palmitic acid (link). However, when compared to palm oil, myristic acid raises total cholesterol more (link). All this goes to show that it's surprisingly difficult to draw conclusions about how saturated fat from natural sources affects cholesterol levels based on studies using single fatty acids.
The third and final point is that the effect of saturated fat on total cholesterol levels is not very interesting, since total cholesterol is a poor predictor of disease. Rather, it's the effect on triglycerides, the LDL/HDL ratio, and the size of lipoprotein particles that we're mostly interested in. And, unfortunately for those who are scared of saturated fat, reducing saturated fat intake decreases HDL, especially large HDL (link). On the other hand, increasing saturated fat intake decreases triglycerides, increases HDL size (link) and increases LDL size during low-carb diets (link). High HDL combined with large LDL and HDL particle size is common among people who are long-lived (link).
As for how individual saturated fatty acids affect these factors, different studies report different findings. Most reviews on the subject agree that all saturated fatty acids except stearic acid increase LDL (link). Lauric acid has been shown to increase especially HDL (link), while stearic acid was shown to improve the ratio of total cholesterol to HDL more than palmitic or myristic acid (link). In fact, palmitic acid doesn't seem to change HDL one way or the other, whereas myristic acid increases it, albeit less than it increases LDL (link).
So, to wrap things up, the take home messages of the above are:
- The effect on cholesterol depends on the length of the carbon chain: in general, stearic acid is neutral, while palmitic acid, myristic acid and lauric seem to increase total cholesterol.
- Saturated fats don't exist in a vacuum: all the other stuff in the diet will also make a difference in how cholesterol levels are affected by saturated fat.
- Make sure you know what you're trying to achieve: if avoiding saturated fat, care should be taken to minimize reductions in HDL levels and lipoprotein particle size.
For more information on fat and cholesterol, see these posts:
SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits
Blood Test Analysis: The Cholesterol and Saturated Fat Issue Revisited
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men
Anthocyanins from Berries Increase HDL and Lower LDL
Read More......
Thursday, September 10, 2009
Two Brave Men Who Ate Nothing But Meat for an Entire Year
Low-carb diets and paleolithic nutrition are all the rage these days, and for good reason. Compared to the Standard American Diet, both of them are superb.
Few of us would dare to take the two to their extreme, however. Giving up sugar and wheat is one thing, but what about giving up everything except meat? Yes, I'm talking about an ultra low-carb diet with even foods like nuts and berries removed. Unsurprisingly and understandably, studies on the long-term effects of such a diet are severely lacking.
There is at least one study that did just this, however. If the diet brings the Eskimos to mind, it's no coincidence. You may have heard of Dr. Vilhjalmur Stefansson – the Canadian ethnologist who spent more than a decade with the Inuit during his arctic explorations in the beginning of the previous century. For nine of these years, he lived almost exclusively on fish and meat (you can read about his experiences here). At the time, this was considered heresy and life-threatening, just as it is today (note that Stefansson apparently refers to both fish and meat with the word "meat"):
A belief I was destined to find crucial in my Arctic work, making the difference between success and failure, life and death, was the view that man cannot live on meat alone. The few doctors and dietitians who thought you could were considered unorthodox if not charlatans. The arguments ranged from metaphysics to chemistry: Man was not intended to be carnivorous - you knew that from examining his teeth, his stomach, and the account of him in the Bible. As mentioned, he would get scurvy if he had no vegetables in meat. The kidneys would be ruined by overwork. There would be protein poisoning and, in general hell to pay.
To the surprise of many (including Stefansson himself), he suffered no health problems during his decade of pure carnivorism. When he told people of his amazing experiences, he was met with skepticism from medical authorities who asked him to undertake a study that would replicate the results. He and a fellow explorer named Andersen agreed to eat an all-meat diet for an entire year in a closely observed setting.
Composing a diet of nothing but meat and fat
This time, however, the diet was even more radical than the traditional Eskimo diet, which is based on fish and includes a small amount of berries and vegetables – not a lot, but enough to keep them out of ketosis most of the time. Furthermore, since fish is high in omega-3 fatty acids, you could argue that it's all those good fats that keep the Eskimos free of disease.
But how could anyone subscribing to conventional health wisdom explain thriving on a diet consisting solely of red meat? No vegetables, no fruit, no vitamin supplements. Nothing. Just meat and animal fat.
The results of this fascinating study were published in 1930 in the Journal of the American Medical Association (link). At the beginning of the experiment, Stefansson was given only lean meat at the request of his supervisors. This was to confirm Stefansson's bad experiences with low-fat meat; during his explorations, there had been periods during which fat was not readily available and which lead to diarrhea and nausea in a few weeks. This time, the illness kicked in much earlier:
As said, in the Arctic we had become ill during the second or third fatless week. I now became ill on the second fatless day. The time difference between Bellevue and the Arctic was due no doubt mainly to the existence of a little fat, here and there in our northern caribou - we had eaten the tissue from behind the eyes, we had broken the bones for marrow, and in doing everything we could to get fat we had evidently secured more than we realized. At Bellevue the meat, carefully scrutinized, had been as lean as such muscle tissue can be.
After fat was added back into the diet, a full recovery was made in two days. The authors of the study describe the diet from then on:
The meat used included beef, lamb, veal, pork and chicken. The parts used were muscle, liver, kidney, brain, bone marrow, bacon, and fat.
Thus, fat played an important part in their diets. According to the authors, Andersen usually ate beef, while Stefansson often chose lamb. Both men ate about 800 grams of meat per day in 3-4 meals. The protein contents ranged from 100 to 140 grams, the fat from 200 to 300 grams, and carbohydrates from 7 to 12 grams. In calories, the percentages were 15-25% protein, 75-85% fat, and 1-2% carbohydrate. The carbs came solely from the glycogen of the meat, making this not so much a low-carb as a no-carb diet. In addition to water, coffee and tea were allowed throughout the period.
Health markers after one year
Examinations at the end of the observation showed that both men were healthy while on the diet. The authors write:
There were no subjective or objective evidences of any loss of physical or mental vigor. The teeth showed no deterioration and gingivitis had disappeared. There was, however, an increase in the deposit of tartar on the teeth of [Stefansson]. Bowel elimination was undisturbed.
Though neither man was overweight to begin with, and weight loss was not the goal of the experiment, both men lost a few pounds during the year. This was despite the fact that calorie intakes ranged from 2,000 to 3,100 kcal. Stefansson averaged about 2,650 kcal (2,100 from fat and 550 from protein), while Andersen averaged 2,620 kcal (2,100 from fat and 510 from protein).
Given that Stefansson, the taller of the two, was 180 cm (5 feet 11 inches), and both of them were fairly sedentary, this represents a significant amount of calories without any weight gain. During the first weeks, weight loss was more significant, apparently due to a shift in the water content of the body. Both men appeared "ruddier" at the end of the experiment than at the beginning.
Blood pressure did not increase in either subject. Stefansson's blood pressure remained at 105/70 mm. throughout the study, while that of the other subject decreased from 140/80 to 120/80 mm. Salt intakes were fairly low.
No physical fatique or problems sticking to the diet were experienced by the two men. Only when the protein content of the diet increased substantially (45% of calories, 55% fat) did problems with digestion occur. Replacing excess protein with fat (20% protein, 80% fat) quickly resolved them, however.
No clinical evidence of vitamin or calcium deficiency was noted, despite the diet being both acidic and low in calcium. In addition, the mild gingivitis Stefansson had suffered from, cleared up entirely during the meat diet. Interestingly, Andersen reported that his hair stopped falling out shortly after the meat diet was started; Stefansson also noted his hair started growing thicker and his scalp was healthier.
Acetone bodies in daily averages per experimental period ranged from 0.4 to 7.2 gm, with the maximum excretion measured during the year being 12.3 gm. The acidity of the urine showed a 2-to 3-fold increase, which is consistent with the highly acidic nature of the diet. A slight increase in uric acid nitrogen was found during the first three months only.
All in all, no evidence of irritation to the kidneys was found – despite the fact that these men were in ketosis practically for an entire year. A higher degree of ketosis was noted when the fat content of the diet increased and the protein content decreased. Acetone bodies quickly disappeared when carbohydrates were introduced into the diet.
In general, the men were in ketosis whenever the ratio of fat to carbohydrates was over 1.5. With the extremely small amounts of carb in their diets, no definite relation between the amount of acetone bodies and the ratio of fat to carbs was found. Stefansson's friend, who was smaller and had less subcutaneous fat, had the highest sustained ketosis.
Seven years after the meat diet
In 1935, one of the authors published an article titled "A Year's Exclusive Meat Diet and Seven Years Later", in which he revisits Stefansson's case (link). First, he summarizes the main points of his earlier article from 1926, titled "The Effects of an Exclusive Long-continued Meat Diet". The following medical facts regarding Stefansson's life during his explorations are listed:
- He spent altogether altogether eleven and one-half years within the Arctic Circle.
- He lived for a number of days, totaling nine years, on an exclusive meat diet.
- He lived for nine successive months on an exclusive meat diet.
- He reached his maximum weight while subsisting on meat (fish).
- His sense of physical and mental well being was at its best during that period of his life.
- He found that the exclusive meat diet worked as well when he was inactive as when active, and as well in hot weather as in cold.
- Constipation was never present. One month's entire absence from exercise produced neither constipation nor muscular weakness. (Stefansson avers that not a single case of constipation was observed in 600 exclusively meat-eating Eskimos for a period of three years).
- His hair thickened, and his scalp became healthier.
- Tooth decay was apparently much less rapid.
Seven years after the meat diet study, the author examined Stefansson again, who apparently had reacquainted himself with some aspects of the Western diet. Instead of eating only meat, he was now eating a breakfast of one egg, bread and coffee, and a dinner and supper consisting of a moderate amount of meat, vegetables, and some cheese. His fruit and milk intake remained negligible.
During this period, Stefansson had put on quite a bit of weight. He now weighed 84 kg, compared with 70.8 kg in 1922 and 72.5 in 1928. His hair was as thick as before, but his gingivitis had returned. Blood pressure was up to 120/80 mm. All in all, the author states Stefansson was in excellent general health. Looking at the numbers, however, it seems that he was doing better on his monotonous carnivore diet.
While it would be interesting to replicate the study with a larger sample size and have more health markers measured than the ones used in the study, it is quite remarkable to see that a diet consisting of nothing but meat and animal fat is both feasible and, apparently, healthy. It also lends support to the importance of having a sufficient amount of fat in the diet, especially when protein is present in significant quantities.
For more information on diets and health, see these posts:
Red Meat and Mortality: A Closer Look at the Evidence
A Typical Paleolithic High-Fat, Low-Carb Meal of an Intermittent Faster
SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits
Protein, Vitamins and Wound Healing
Read More......
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