Tuesday, January 25, 2011

Genes, Diet and Oral Health: Why Do Some People Get Cavities and Others Don't?

Genes, Diet and Oral Health: Why Do Some People Get Cavities and Others Don't?
Getting rid of candies didn't prevent me from getting caries. (Photo by exper)

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......

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Monday, January 10, 2011

Green Tea as a Pro-oxidant: Too Much of a Good Thing?

Is too much green tea harmful for you?
Is too much green tea harmful for you? (Photo by tornado_twister)

I was browsing through the latest studies on green tea and came across a paper saying EGCG, one of the green tea polyphenols, increases protein cross-linking (link). I was intrigued, because this was the first time I'd heard of such an effect. The abstract also mentions that there's increasing evidence EGCG can generate reactive oxygen species and break DNA strands in biological systems. In effect, it says that the antioxidant is actually a pro-oxidant.

I looked up some of the references and indeed, even green tea's polyphenols (at least EGCG, possibly some others) have oxidative effects under certain in vitro conditions. For example, in human whole blood lymphocytes, EGCG either suppresses or induces DNA strand breakage, depending on the concentration.

In concentrations between 0.01-10 μM (micromoles/L), strand breakage decreases, but once the concetration gets higher than 1000 μM, it increases instead. In purified blood lymphocytes, concentrations of 1-100 μM induce and concentrations of 0.01-0.1 μM suppress DNA strand breakage.

Sounds an awfully lot like hormesis, doesn't it? As with everything, the dose makes the poison. The interesting part, of course, is whether drinking green tea can cause similar harmful effects in real life.

Luckily, one study looked at the effect of green tea on DNA strand breaks in rats (link). The smaller dose (which according to the authors is equivalent to one desiliter of green tea in humans) had no effect, but the larger dose (equivalent to half a liter) significantly reduced strand breaks.

Half a liter of green tea, equal to about three cups, increase total plasma antioxidant capacity only moderately. When only EGCG is taken into account, the results vary somewhat from study to study, but concentrations rarely exceed 1 μM (link). Also, plasma antioxidant activity has a plateau, which suggests that the absorption mechanism of green tea polyphenols becomes saturated after a certain point:

To make the tea used in the study, 500 ml of boiling water was poured on 20 grams of green tea leaves (8-10 tea bags), and the tea was then allowed to infuse for 10 minutes. That makes for a very strong tea, much stronger than the ones used in the other studies. The volunteers drank 300-400 ml of the tea, after which blood samples were collected at different time intervals

In this study, there was no difference between those who drank 300 and 400 ml of the tea. Even then, the increase in antioxidant activity was only 4% at the peak. Thus, it seems unlikely that harmful levels could be reached by simply drinking plenty of green tea. In one Asian population, 10 cups of green tea daily reduced total mortality compared to those who drank less green tea and/or smoked.

Theoretically at least, extracts and supplements could be a different matter, because they often contain a higher percentage of EGCG than green tea and come with things that increase absorption. For example, piperine increases plasma levels of EGCG.

One green tea extract containing 40% EGCG resulted in a peak  of 0.8 μg/mL in human subjects; when the same extract was complexed with phospholipids, the peak was 1.9 μg/mL. If my calculations are correct (which they often aren't; please correct me if I'm wrong), then these would be ~1.75 μM and ~4.14 μM, respectively. Again, in whole blood lymphocytes concentrations between 0.01-10 μM, strand breakage was decreased, and it took concentrations higher than 1000 μM to increase strand breakage.

All in all, it appears that green tea in reasonable quantities (at least up to 10 cups) does not cause it to act as an oxidant in vivo. It's unknown what a much higher amount would do, assuming you could somehow bring yourself to drink 50 cups. I haven't seen any human studies on such amounts. But if the plateau effect is indeed true, then you might not be able to reach high plasma levels of EGCG no matter how much you drink.

With supplements, the situation is different. Piperine and phospholipids make reaching higher plasma values possible, which can be a good thing or a bad thing, depending on what you're using the supplements for. Some conditions require higher doses than others, so you'll have to judge the proper approach on a case by case basis. However, since EGCG does have the potential of being a pro-oxidant in vitro and is toxic to the liver in very high amounts, be careful not to overdo it with green tea supplements.

For more information on green tea and health, see these posts:

Green Tea Protects from the Psychological Effects of Stress in Rats
Tea, Coffee and Cocoa: All Good for Your Teeth
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
Green Tea Catechin Reverses the Effect of DHT in Prostate Cancer Cells

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Wednesday, January 5, 2011

Dark Chocolate Reduces Blood Pressure and Improves Insulin Sensitivity in Just Two Weeks

Dark Chocolate Reduces Blood Pressure and Improves Insulin Sensitivity in Just Two Weeks
Not all things that are good for you taste bad. (Photo by CC Chapman)

Everyone knows that dark chocolate is healthy, but how many of us really know why exactly it's healthy? It's the same as with red wine: it's common knowledge that it's healthy – it contains those magical polyphenols, after all – but the actual effects are mentioned less frequently.

Most things that are labeled healthy by mainstream media are things that reduce the risk of cardiovascular disease. The same is true of red wine and dark chocolate, although I'm sure there's more to them than just heart health. Resveratrol, found in red wine, for example has a multitude of effects. What I found interesting, however, is how quickly dark chocolate can have a beneficial effect on two common health problems: blood pressure and glucose intolerance (link).

Study design

To study how dark chocolate affects glucose tolerance, insulin sensitivity and blood pressure, 19 subjects with hypertension and impaired glucose tolerance were chosen for the experiment. Smokers and those with significant overweight (BMI > 30) or diabetes were excluded.

The subjects were then randomized and given either 100 grams of flavonol-rich dark chocolate or flavonol-free white chocolate for 15 days. They were told to eat the chocolate in two 50 gram doses, one for breakfast and one for lunch. After a washout period of one week the two treatments were switched, so that those who had been eating dark chocolate got white chocolate instead and vice versa.


Two weeks of dark chocolate consumption decreased insulin resistance significantly compared to baseline and white chocolate. The graphs below show the results from various measurements.

Insulin sensitivity and dark chocolate

The graph on the left show the results from the homeostasis model asssessment of insulin resistance (HOMA-IR) for baseline, flavonoid-rich dark chocolate (FRDC) and flavonoid-free white chocolate (FFWC). The three other graphs show the differences in insulin sensitivity. White chocolate had no effect on any of the tests, while dark chocolate improved glucose and insulin responses to the oral glucose tolerance test.

Compared to baseline, blood pressure decreased after dark chocolate consumption. White chocolate had no effect on 24-h, daytime or nighttime blood pressure. The graphs below show the changes in systolic and diastolic blood pressure.

Dark chocolate also increased flow-mediated dilation, which measures endothelial function. Again, white chocolate had no effect compared to baseline. Interestingly, dark chocolate also reduced LDL cholesterol compared to baseline and white chocolate but had no effect on triglycerides and HDL.


In people with hypertension and impaired insulin sensitivity, dark chocolate (but not white chocolate) reduced blood pressure and improved glucose tolerance and insulin sensitivity. Endothelial function was also improved.

What's interesting about this study is that the duration was so short: the participants saw improvements in just two weeks. And, unlike in many studies, they weren't given cocoa powder or a small dose of dark chocolate, but an entire 100 gram chocolate bar for each day. Also, the subjects were not diabetic, and they only had stage 1 hypertension (systolic 140-159 mmHg, diastolic 90-99 mmHg), which suggests that dark chocolate is helpful even before things get really bad.

I try to keep my intake at around 50 grams per day on average, but at least this study shows that higher amounts are not bad for cholesterol, blood pressure or insulin sensitivity. The reasons I try to stay below 100 grams are the high iron and copper contents and possible lead contamination in cocoa powder.

Still, if you're eating milk chocolate with a low cocoa content (typically around 30%), consider upping the ante and slowly progressing towards darker chocolates. It's the better choice in at least five different ways.

For more information on blood pressure, insulin and cholesterol, see these posts:

Hibiscus Tea Increases HDL, Lowers LDL and Triglycerides
The Many Health Benefits of Rooibos Tea
Intermittent Fasting Improves Insulin Sensitivity Even without Weight Loss
Intermittent Fasting with a Condensed Eating Window – Part III: Fasting Blood Glucose, Cortisol & Conclusion

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Monday, January 3, 2011

Nootropics, Longevity and More: The Year 2010 in Review

Comments or suggestions for the year 2011? Drop a comment!
Comments or suggestions for the year 2011? Drop a comment! (Photo by Altus)

Happy New Year everyone! I hope your holidays went well and you're ready to make 2011 even better than last year. But before we do that, let's take a look at some of the best bits and pieces from 2010.

In January, I finally got a chance to see Aubrey de Grey for the first time. His presentation in Helsinki, Finland was mostly familiar to me already, but I enjoyed it nonetheless. Perhaps the most interesting part was when the audience got to ask questions; I thought Aubrey's answers were good, especially given that some of the comments were pretty frustrating (apparently some people think going through their entire family history somehow qualifies as a question). If you want to check out the presentation, the video is still available online through the link above. And in case you want to know more about Aubrey himself, he was also interviewed in Wired.com a while ago.

Nootropics are gaining more and more attention these days. Even 60 minutes ran a segment on students boosting brain power to do better in their studies. Amphetamine derivatives are still the most popular choice – but whoever comes up with an "organic herbal formula" that actually works as well as Adderrall is going to be rich. I also did an experiment with Ashwagandha to see whether it had a nootropic effect. It didn't, at least not the brand I was using.

And then there was the experiment with BioSil, the stuff that is supposed to make your hair and nails stronger. The science seems solid, but as I wrote in my conclusion, the price of the liquid supplement doesn't seem worth it, since orthosilicic acid, the active ingredient, is also present in my favourite beverage.

Speaking of hair, a lot of people have asked for an update on the soy isoflavones + capsaicin experiment, another one of my attempts at finding a magical hair growth formula that will make me filthy rich. The experiment has been going on for six months now, which is longer than the five months that the original study lasted, so perhaps a proper update is indeed due. So far I haven't seen much visible changes, however. I'm now adding various kinds of chili powders and pastes to almost all my foods, but I'm thinking of ordering capsaicin supplements to be sure I'm getting enough to match the study. And I also need another bottle of soy isoflavones.

I've tried a lot of useless supplements and topicals, but last year I came across something that really, actually works: retinoids. I've now been using them for over a year and I can really see the difference. My advice to anyone looking for real results is to forget about all the overpriced skin creams that are really nothing but moisturizers and go for tretinoin instead. Of course, since it actually works it's prescription stuff, so you can't just buy it from the store, you'll have to order it online and hope your package doesn't get confiscated by the customs officers who surely know better what you need than you do. Thank god for regulations!

Probably the longest and most throrough post of last year was about human hibernation and how it might relate to longevity. In addition to a look at the current state of hibernation science, there's also the odd legend of lotska, the art of hibernation allegedly practiced by poor Russian peasants:

At the first fall of snow the whole family gathers round the stove, lies down, ceases to wrestle with the problems of human existence, and quietly goes to sleep. Once a day every one wakes up to eat a piece of hard bread, of which an amount sufficient to last six months has providently been baked in the previous autumn. When the bread has been washed down with a draught of water, everyone goes to sleep again. The members of the family take it in turn to watch and keep the fire alight.

And of course, no post on slowing down metabolism would be complete without Indian fakirs and frozen mountain climbers. Check it out if you have the time, it's fascinating stuff.

While the Russian peasants may have spent most of their winter sleeping to avoid starving, there are also those who can eat as much as they like and still avoid getting fat. Even without any exercise. I'll let other bloggers fight it out over the details of the energy equation and whether a calorie truly is a calorie, but take a look at the BBC documentary in the link to see what I mean. Also check out the comment section, some interesting anecdotes in there.

How is the life extension movement doing these days? Well, the same old (and false) arguments against longer lifespans are still there, but the overall mood is pretty optimistic. Personally, I've noticed that younger people tend to be more open to the possibility of life extension than middle-aged people. Go figure. Meanwhile, the Russians have apparently found the cure for aging, although I haven't heard anything new on SkQ1 since September. But that's okay, because the next fountain of youth is already here.

Long-time readers of this blog probably remember that I did intermittent fasting for over a year. Part of the reason was that I wanted to see if 24-hour fasts could be done – I wanted to be the master of my hunger, so to speak. However, the most important reason were the studies showing positive effects from intermittent fasting without restricting total calories. You know, the whole "cleaning cells from junk through autophagy" thing.

But alas, after going through the studies more carefully, I was disappointed to find out that whenever intermittent fasting increased lifespan in mice, total calories had also been restricted. In effect, intermittent fasting extends lifespan only in conjuction with caloric restriction. Some of the other benefits of fasting may still be valid, to a degree at least, but without potential gains in lifespan, I don't see the point in doing a strict 24/24-hour cycle of fasting and feasting anymore. Besides, I now think that even full-blown calorie restriction would only give me a few extra years. Why? Because humans just can't do CR the same way rodents can. More on this later. Meanwhile, see my updated health regimen.

Of course, there were also several other posts which I didn't mention here; see the archives section in case you missed them. And just so you don't miss anything interesting in the future, remember to subscribe to my feed and to follow me on Twitter, which I use to post stuff (life extension, health, science) I don't have time to blog about in depth. Oh yeah, and tell your friends to do so too!

For summaries of previous years, see these posts:

10 Human Experiments of 2009 – Year in Review
7 Human Experiments of 2008 – Year in Review

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