Found this about zinc from another board...

[D-F]

Zinc May Help Prevent Gynecomastia ("Bitch's Tits")
You may significantly be able to reduce the chances of getting gynecomastia, "bitch's tits," with a simple, inexpensive, legal supplementation—zinc. Here's the evidence.

First some background.

BALCO Laboratories of Burlingame, California, has done what is called multi-element analysis, a measurement of the levels in parts per million of between 20 and 30 different trace minerals and toxic metals, on more than 200,000 people. The procedure uses blood and urine samples. The blood samples used consist primarily of red blood cells and plasma. Many of the people analyzed are elite, professional and Olympic athletes such as the Seattle Supersonics, the Denver Broncos, and the Miami Dolphins, and at least 20 to 25 professional bodybuilders. For a technological description of the method and early applications to sports, watch this area of musclephotos.com. This description will soon be posted.

From these analyses, BALCO Labs, Inc., has established that somewhere between 70 and 80% of the athletes tested are either "low" or "deficient" in zinc. For instance, among professional football players, the percentage is approximately 73%. Among professional bodybuilders, a depletion or deficiency of zinc also seems prevalent.

The answer may lie in an older article by Ae-Son Om and Kyung-Won Chung, published in the April 1996 Journal of Nutrition, 126[4]: 842-848. The article is entitled "Dietary Zinc Deficiency Alters 5 Alpha-Reduction and Aromatization of Testosterone and Androgen and Estrogen in Rat Liver." Both researchers are from the Department of Anatomical Sciences in the University of Oklahoma College of Medicine. They had done a previous study in 1990 on why alcoholics and coke addicts develop feminine characteristics. In this study, they had found that the hepatic aromatization of androgens to estrogens is enhanced by alcohol ingestion and cocaine administration. Both alcohol and cocaine also lower an individual's zinc levels, sometimes beyond depletion into actual deficiency. In their new work they sought an anatomical/biological explanation of why this occurred.

In their new work, they used three populations of rats. (I can hear the critics' knee-jerk response: "But-rats-aren't-the-same-as-human-beings." Let me just note that rats have been used in biological investigations for years because a great many of their biological characteristics resemble those humans. It is also a lot easier to kill a rat for a microscopic anatomical investigation than it is to kill a bodybuilder. While one must be very cautious about extrapolating explanations from research with rats, sometimes this type of research can explain much that happens to people.)

The three populations of rats included a group fed a zinc-deficient diet, a group fed a controlled but adequate diet of zinc, and a freely fed group.

After keeping these populations on these diets for a long enough time to affect their plasma zinc levels, the scientists measured their testosterone and estrogen levels and measured and counted their androgen and estrogen receptor sites.

Among the zinc deficient rats, they found the androgen receptor sites had become reduced in number and size by 40%. At the same time, the estrogen receptor sites increased by 60%. The liver's conversion of testosterone to estrogen was significantly greater in the rats on the zinc deficient diet. The same rats that had the decrease in androgen receptor sites showed significantly reduced amounts of lutinizing hormone and testosterone concentrations.

Having a zinc-deficient diet evidently increased the aromatization of testosterone and the formation of estradiol, the primary estrogen hormone.

One of the same researchers, Chung An, had also published research in Life Science, January 27, 1986, 38 [4]: 351-356, entitled "Androgen Receptors in the Ventral Prostate Gland of Zinc Deficient Rats." In this reasearch study,. there were only two groups of rats—those fed a zinc deficient diet for three months and those fed a controlled (zinc adequate) diet for the same amount of time. Analysis of the data revealed that the number of androgen binding sites of the zinc deficient rats' prostate was 31 fmol/mg cytosal protein. This was significantly lower than the 84 fmol/mg protein of the controls.

Figure it out. Divide 31 by 84 and you have a 63% reduction in the number of androgen binding sites.

If some of the testosterone (androgen) has nowhere to go—nowhere to bind—it will continue to circulate in the blood, finally being aromatized in the liver and producing estrogen. Bitch's tits, here you come!

The lesson is very clear. If you are taking steroids, you probably should be taking supplemental zinc in order to reduce your chance of developing gynecomastia ("bitch's tits). Observe this warning: a multi-vitamin/multi-mineral tablet or two will not work. For reasons which will be explained later on this site, and which have been published numerous times in numerous places, these supplements are ineffective as far as zinc is concerned.

A few additional comments. At least one of the "experts" in the newsgroup misc.fitness.weights has stated that all this material about zinc is "already known" and that gynecomastia "is not a serious problem in bodybuilding."

Judge for yourself. When suggesting dosages of steroids to you, have these "experts" advised you to take zinc supplements? If they haven't, then this would suggest that they really don't know about the importance of using zinc in this situation. Interesting observation: Not a single professional bodybuilder out of the more than 20 we have recently tested and talked with has known of the connection between zinc deficiency and gynecomastia. If this information is so well known, you'd think the people who professionally need it the most would know it, wouldn't you?

As to gynecomastia not being a serious problem., all we can say is that professional bodybuilders take the problem very seriously indeed. We've questioned them about this. We know.

Armed with this information, you'll be able to walk into your local health food store and buy something that will actually do you some good instead of just lulling you into a false complacency.

Very insightful info....

D-F.

Nice article, good to know!

Ghostdog....

[Daren]

Good info bro! I never thought zinc was so important.Now im glad i read it.

[Juicygirl]

THANKS! Wonderful article and great info!! thanks so much for sharing!!!!!!