Green Tea Reduces the Formation of AGEs

Green tea extract reduces the amount of AGEs in milk processing. (Photo by yomi955)

These days pretty much everyone knows about the beneficial health effects of green tea. It seems that scientists come up with new studies every week showing how green tea improves health. A lot of these just verify things we already know (or think we do), but the effect of green tea on AGEs (Advanced Glycation End products, a result of the Maillard reaction) is a relatively new and interesting question.

Not many studies have been done on green tea and reducing AGEs, but the ones that have been done look promising. From Babu et al.:

Diabetes leads to modification of collagen such as advanced glycation and cross-linking which play an important role in the pathogenesis of diabetes mellitus. We have investigated the effect of green tea on modification of collagen in streptozotocin (60 mg/kg body weight) induced diabetic rats.

To investigate the therapeutic effect of green tea, treatment was begun six weeks after the onset of diabetes and green tea extract (300 mg/kg body weight) was given orally for 4 weeks. The collagen content, extent of advanced glycation, advanced glycation end products (AGE) and cross-linking of tail tendon collagen were investigated. Green tea reduced the tail tendon collagen content which increased in diabetic rats. Accelerated advanced glycation and AGE in diabetic animals, as detected by Ehrlich’s-positive material and collagen linked fluorescence respectively were reduced significantly by green tea. The solubility of tail tendon collagen decreased significantly in diabetic rats indicating a remarkable increase in the cross-linking, whereas green tea increases the solubility of collagen in diabetic rats.

The present study reveals that green tea is effective in reducing the modification of tail tendon collagen in diabetic rats. Thus green tea may have a therapeutic effect in the treatment of glycation induced complications of diabetes.

In short, they fed green tea extract to diabetic rats and noticed it reduced AGEs in their connective tissue. That's good news. Similar results are reported by Ping et al.:

OBJECTIVE: To determine the effects of green tea polyphenols (GTP) on advanced glycation end products (AGEs)-induced proliferation and expression of p44/42 mitogen-activated protein kinase (MAPK) of rat vascular smooth muscle cells (VSMCs).

METHODS: Rat aortic VSMCs isolated and cultured in vitro were stimulated with AGEs in the presence or absence of GTP at different concentrations, followed by quantitative analysis of the cell proliferation with colorimetric assay. The p44/42 MAPK activity was evaluated by immunoblotting technique using anti-p44/42 phospho-MAPK antibody.

RESULTS: Compared with the control cells (without GTP treatment), GTP dose-dependently inhibited AGE-stimulated VSMC proliferation, and the p44/42 MAPK activity was significantly enhanced. The effects of AGEs were antagonized by GTP.

CONCLUSION: GTP can inhibit the AGE-induced proliferation and p44/42 MAPK expression of rat VSMCs.

This time the effect of green tea polyphenols on heart muscle cells was studied; again, AGE production was reduced. The effect was dose-dependent, meaning that the more green tea polyphenols the rats consumed, the less AGEs their muscle cells had. In another heart-related study, Song et al. report the following findings:

In this study, 6-month-old female Sprague–Dawley rats were fed green tea extract (50 mg/100 ml in drinking water) up to the age of 22 months, and the age-associated changes in Maillard-type fluorescence and carbonyl groups in the aortic and skin collagen were compared with those occurring in the water-fed control animals.

Collagen-linked Maillard-type fluorescence was found to increase in both the aortic and skin tissues as animals aged. The age-associated increase in the fluorescence in the aortic collagen was remarkably inhibited by the green tea extract treatment, while that occuring in the skin collagen was not significantly inhibited by the treatment.The collagen carbonyl content also increased in both the aortic and skin tissues as animals aged. In contrast with the case of Maillard-type fluorescence, however, the age-associated increase in the carbonyl content was not inhibited by the green tea extract treatment either in the aortic or skin collagen.

These results suggest that the inhibition of AGE formation in collagen is an important mechanism for the protective effects of tea catechins against cardiovascular diseases. Increases in fluorescence are considered a marker of AGEs; this study shows that rats fed a green tea extract had less AGEs in their aortas. Unfortunately, a similar effect was not noticed in the skin.

Comparing green tea with vitamin C and E and blueberries, Monnier et al. report:

Both green tea and the combination of vitamin C and E were highly efficacious at blocking the age-related increase in tendon-breaking time. Furthermore, green tea also blocked the age-related increase in collagen associated fluorescence without decreasing glycemia or body weight of the animals. Thus, it appears that green tea ingredients have potent anti-AGE properties.

The figures in the study (which are available through the link) show that the combination of vitamin C and E was more effective than green tea in reducing the tendon-breaking time – which increases with age – but less effective than green tea in reducing fluorescence.

Finally, green tea catechins seem to reduce AGEs in heat-processed milk as well. From Schamberger & Labuza:

This research studied the effectiveness of using EC and EGCG in a model system as well as in thermally processed milk. The addition of these extracts was found to reduce Maillard browning associated fluorescence and color change during UHT milk processing. During storage EC and EGCG at a 1.0 mmol concentration reduced Maillard fluorescence to a negligible level in the glucose/glycine mixtures and milk samples. Maillard fluorescence was also reduced when these compounds were used at a level of 0.1 mmol in milk during storage. Consumer sensory testing analysis found the green tea milk samples were liked as well or better than the control milk samples. These results indicate that EC and EGCG have potential for use as Maillard browning inhibitors in food.

UHT processing of milk produces a lot of AGEs (significantly more so than ordinary milk). This study shows that adding green tea catechins to the milk reduced AGEs to negligible levels. The authors suggest that green tea might work similarly for other foods as well.

So what is the take home message from all this? The 300 mg/kg used in the first study is not directly translatable to humans; for an average male of 70 kg, that would be equal to 21 grams of extract. One green tea capsule meant for humans might have anywhere between 50 mg and 1 gram of extract, so matching the rats would mean taking at least 21 capsules.

The good news is that a lot of the other studies on green tea in humans show that much lower amounts are needed to get benefits. Anywhere between 2 and 10 cups of green tea per day is a reasonable amount, or if you want to take the supplement route, one to three capsules will usually equal the same amount (depending on how strong the extract is, of course).

For more information on green tea, see these posts:

Drinking 10 Cups of Green Tea Daily and Not Smoking Could Add 12 Years to Your Life
Black Tea is More Effective in Reducing Superoxide Dismutase than Green Tea
Dental Health Effects of Green and Black Tea
Green Tea Extract Grows Hair in Vitro, May Work in Vivo

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Peruvian Maca: Does It Really Increase Energy and Sex Drive?

Maca grows in the high altitudes of the Andes. (Photo by kyle simourd)

Maca root is yet another supplement touted as an ancient secret used for centuries by [insert exotic culture here] to cure [insert list of various ailments here] - and, of course, to generally improve your life. It might even help you win the lottery, if the salesmen are to be believed.

Peruvian maca, the story goes, was used by the Incas in the past for a host of health problems. Today maca is prescribed for things like hormonal imbalance, post-menopause syndrome, infertility, lack of libido, impotence and mental clarity. It is still used by the people in the Andean region as an aphrodisiac and to increase physical endurance and energy.

These are impressive claims, but are they true? Fortunately, one doesn't have to rely entirely on the word of the people who sell the stuff, since the revival of this magical root has sparked some actual scientific studies.

Studies on humans

In a 12-week double-blind study, men aged between 21 and 56 years received 1,500 mg or 3,000 mg of maca. After 8 weeks, the maca group reported improvements in sexual desire. The subjects were also asked to evaluate their depression and anxiety to see whether they correlated with the sexual desire evaluations. Neither of these factors however explained the reported improvement in libido.

In another paper by the same authors, hormone level differences between the maca-fed group and the placebo group were analyzed. No changes were noticed in any of the hormone levels studied - including testosterone. Correcting hormonal imbalances with maca, as some doctors apparently do, thus seems useless. The reported improvements in sexual desire appear not to be due to changes in hormone levels but to something else.

When the same amount of maca (1,500 mg or 3,000 mg per day) was given to nine male subjects, seminal volume, sperm counts and sperm motility improved. Again, the results were not due to changes in hormone levels.

Studies on rats

Similar improvements in spermatogenesis were seen on rats when they were exposed to high altitudes. The sperm counts of the maca-fed rats in the high-altitude group were similar to those of the sea-level group fed with maca and better than those of the sea-level group not fed with maca. The authors conclude that the "treatment of rats with maca prevented high altitude-induced spermatogenetic disruption".

In rats, prostate size was reduced when they were fed red maca for 42 days. Serum testosterone and estradiol levels were unchanged. Yellow and black maca, however, had no effect on prostate size. It is unclear which type of maca was used in the human studies.

Extracts of maca seem to work too: when an 5% alcoholic extract was fed to rats, sperm production was increased after 21 days. On days 7 and 14, however, no changes were observed. Maca extracts also improved other sexual parameters in inexperienced male rats.

Is it safe?

To my knowledge, no adverse effects from maca have been reported in either rats or humans. In rats, maca seems to be well tolerated even at high doses. This study showed that maca extract had no toxic effects in doses up to 5 g / kg of body weight. In a 70 kg human male, this would be equal to the intake of 770 g dry maca powder, which is a lot more than you'd be able to eat in one day (unless maybe you're a really big fan of the taste).

The amounts used in the human studies are much less than that. In all three studies the subjects were given between 1,5-3 grams, which is less than a teaspoon. Anecdotal evidence suggests that people usually take up to a few tablespoons, which is about 30 grams.

Does it work?

Seeing as this is an ancient miracle just waiting to be discovered, I feel it's my duty to try this sacred powder myself. I'm going to start off with one tablespoon per day. Signs of success in the experiment would include noticeable increases in sex drive, sperm production or overall energy level. The first two have some science to back them up, but the last one is purely anecdotal and the one I feel most sceptical about.

Go to next post on this experiment

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MSM for Hair & Nail Growth - Results after Three Months

MSM won't turn your nails blue - in fact, it seems to do nothing. (Photo by scragz)

In my previous post about methylsulfonylmethane, I mentioned I had ran out of my MSM + chondroitin + glucosamine powder and was looking for another product with more MSM and a lower price tag. The only study done on the subject used 3,000 mg per day, while the product I was testing had only 1,000 mg per serving. Perhaps unsurprisingly, I noticed no results.

Since then, I've purchased a jar of pure MSM, made by Natural Balance. This product has 4,000 mg per teaspoon and is therefore better suited for my experiment. I first started out by taking 2,000 mg (half a teaspoon) of the stuff per day for three weeks. Again, I saw no results.

For the past three weeks I've been taking 4,000 mg, as suggested on the label. At first I took the whole teaspoon at once, but then I separated it into two 2,000 mg portions; one taken in the morning and one in the evening. Even at this dose, I've noticed no increase in the rate of hair growth, nail growth or nail thickness.

At this point, I strongly suspect MSM is ineffective at any dose and that the positive results some people have claimed are most likely due to a placebo effect. Subjective evaluations - which the study was based on - are notoriously untrustworthy, and even objectively measured moderate changes in hair growth and thickness can be due to seasonal variation. Note that my experience is only with MSM's effects on hair and nails - I can't comment on MSM's possible effectiveness for joint pains, as I don't have any.

As I still have some of this hideous-tasting powder left, I'm once again going to take it to extreme (so you won't have to) and double the dose to see what happens. That's right, I'm going for a full 8,000 mg dose; 4,000 mg in the morning and 4,000 in the evening. How I'm going to get so much of this stuff down is beyond me at the moment, but the fact that I'm doing all this in the name of science grants me some comfort in these dark and lonely moments.

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