Sunday, May 8, 2011

Green tea lowers testosterone? By Jerry Brainum

Not long ago, I wrote a two-part article on the benefits of green tea for Ironman. I’ve used green tea (GT) myself for quite some time. It contains some of the most potent natural antioxidants yet discovered, which explains why it offers a myriad of health benefits. While leafing through a magazine that touts itself as being the “premier” bodybuilding science magazine, I noticed an item with the heading “Green tea lowers testosterone.” The way the short item was written appeared to offer convincing evidence that using green tea supplements, or drinking the tea itself, would lower testosterone levels. The item ended by suggesting that perhaps bodybuilders should avoid anything with green tea. Such a suggestion is problematic, because most “fat-loss” supplements sold today contain green tea as a primary active ingredient. On the other hand, attempting to produce any appreciable gains in muscle mass while also consuming a substance that lowers testosterone amounts to working against yourself. You simply cannot build muscle without a certain amount of testosterone. This is an established fact. So what to do about the green tea problem?

I mentioned in my Ironman green tea article how some rat studies in which the rodents were given large doses of green tea antioxidants via intravenous route did appear to lower testosterone in the animals. It also lowered other hormones, including estrogen. But the study showed that when provided orally, green tea had no effect on the hormones.In addition, the rats in the study lost a considerable amount of weight, and it was conjectured that the weight loss, rather than the green tea exposure, is what led to the lowered hormone levels. Losing large amounts of weight rapidly produces similar effects in humans due to a high stress effect.   In addition, other studies with mice and rats show that green tea appears to boost testosterone levels. One mechanism may be an inhibition of the aromatase enzyme that converts androgens, such as testosterone, into estrogen. Test tube studies of rodent cells show that green tea may also inhibit 5-alpha-reductase, the enzyme that converts testosterone into its metabolite, dihydrotestosterone (DHT). The latter causes male pattern baldness, acne, and prostate gland problems.

To  examine the  question of whether new information does suggest an anti-testosterone mechanism associated with green tea , I looked at the actual study, which was published in the Asian Journal of Andrology. This was the same journal that first published articles about an African herb called Fadogia, which was soon followed by some people attempting to peddle fadogia as a potent testosterone producer. My reaction to that was that the evidence for the efficacy of fadogia consisted of folk tales from Nigeria, along with one–count em’– one study of rats. A follow up study by the same researchers found that long-term use of the herb could cause testicular toxicity, which is not exactly amenable to higher testosterone production. Of course, the purveyors of fadogia never mentioned that later study. But back to green tea and testosterone.

The article in the bodybuilding magazine indicated that the study used intact rats. First, what happens in rats doesn’t necessarily also happen in humans. But the study didn’t involve live rats. Instead, it examined isolated Leydig cells obtained from rats. The Leydig cells are the portion of the testes where testosterone is synthesized. The cells were incubated with the active antioxidant constituents of green tea for three hours, along with the testosterone precursor, androstenedione. Some may recall that andro was one of the first prohormones released, and gained fame when baseball slugger, Mark McGwire admitted using it. Of course, now we know what McGwire really used, and it wasn’t an over-the-counter prohormone! The study showed that exposing isolated cells to large amounts of green tea interfered with several pathways of testosterone synthesis. But this involved doses far larger than would be obtained by an oral intake of green tea. In addition, humans can only absorb a small percentage of ingested green tea polyphenols (antioxidants). So in effect, this study was similar to the one that I described in my green tea article. To suggest that consuming green tea in supplement form would produce the same effect is a huge leap of scientific logic. If this were true, most bodybuilders who use green tea supplements in any form would have low testosterone levels, and that is simply not the case. Also, consider that in Asian countries, the average intake of green tea is 10 cups a day. Again, if this were lowering testosterone levels, China would be a vast, uninhabited wasteland. Ditto for Japan. The level of Leydig cell exposure to green tea polyphenols that occurred in the study would never happen in the human body.

So much for the “premier science” bodybuilding rag, er, I mean mag.

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The Applied Ergogenics blog is a collection of articles written and published by Jerry Brainum over the past 20 years. These articles have appeared in Muscle and Fitness, Ironman, and other magazines. Many of the posts on the blog are original articles, having appeared here for the first time. For Jerry’s most recent articles, which are far more in depth than anything that appears on this blog site, please subscribe to his Applied Metabolics Newsletter, at This newsletter, which is more correctly referred to as a monthly e-book, since its average length is 35 to 40 pages, contains the latest findings about nutrition, exercise science, fat-loss, anti-aging, ergogenic aids, food supplements, and other topics. For 33 cents a day you get the benefit of Jerry’s 53 years of writing and intense study of all matters pertaining to fitness,health, bodybuilding, and disease prevention.


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