by Thomas Incledon, PhD(c), RD, LD/LN, RPT, NSCA-CPT, CSCS
Flavone X
Some time ago an article was printed in another magazine about a mysterious compound known as “Flavone X.” This compound was supposed to inhibit the conversion of testosterone (T) to estradiol (E2 -an estrogen). This inhibition would then result in elevated testosterone levels, which would lead to greater gains in muscle size and strength. On paper this sounds awesome. Since then many supplement companies have released products that claim to contain chrysin (Flavone X). With all the hype on testosterone and muscle growth other important facts seem to have been disregarded. In this article I will present the facts to support my opinion why chrysin doesn’t work.
Absorption from the GI Tract
As of September 1998, no supplement studies have been done to show that chrysin can make it from your GI tract into your blood. If it can’t get into your blood then it certainly can not prevent the conversion of T into E2. Chrysin belongs to a family of compounds referred to as flavonoids. These plant-derived substances are generally not absorbed very well from the small intestine (1). It would be logical to think therefore that the absorption of chrysin would be poor. As a result, the bioavailability of the compound would be expected to be very low. Now one can get around this perhaps by taking very large dosages (in the gram range - several times per day) or by taking the substance with a GI expander such as lysophosphatidylcholine (LPC) or plasmalogen. This may work, but once again this has not been studied and is guesswork at best. Given the current cost of this supplement it would seem foolish to spend money on a product that may not even be absorbed.
In addition to the poor absorption of flavanoids, it should also be pointed out that, they could also be metabolized or altered by bacteria in your GI tract (1). What this simply means are that maybe you swallow a few chrysin capsules. Now when it hits your small intestine or large intestine, bacteria may convert it into something else. The something else that it is converted into will most likely not have any effect on testosterone levels.
Let’s say for arguments sake that chrysin makes it into your blood. The first place it travels to is the liver. There liver enzymes cat on it and convert it into another product that will most likely not bind to aromatase (the enzyme that converts T into E2). If it makes it by the liver, it will most likely attach to a blood protein. After that it can’t bind to another molecule so it can’t function as an anti-aromatase.
Chrysin, Aromatase and Other Enzymes
The original study cited to support the idea that chrysin can inhibit the aromatase enzyme was done on isolated cell cultures outside the human body (2). The problem with this is that conditions in a petri dish environment are controlled, whereas in the human body we have a very dynamic internal environment. The enzyme aromatase may not be the only thing affected by chrysin. Since we are dealing with in vitro studies then we should look at others that involve chrysin so that we can see the whole story. Chrysin is known to influence enzymes in the liver that metabolize drugs (3). These same enzymes can also metabolize steroids like T and E2. This means that even though you may increase you T levels acutely, your liver may simply increase its ability to metabolize T into a less effective form. Another important fact is that chrysin has also been shown to decrease insulin production in isolated rat pancreatic cells (4). This is a major anabolic hormone that can possibly be attenuated by chrysin. The point of mentioning these other in vitro studies is that now we can begin to form a more educated guess as to whether or not chrysin can work and/or if it is worth it.
Let’s look at the theory behind chrysin’s supposed actions. The body produces testosterone which aromatase converts into E2 (estradiol—an estrogen). E2 is supposed to be a strong inhibitor of additional testosterone production. It does this by binding to receptors in the hypothalamus and anterior pituitary, which then prevents the release of other hormones that will eventually stimulate the testes to produce testosterone. Now this theory is only partially true. The body can also be inhibited from producing T by the presence of additional T and/or DHT (dihydrotestosterone). This means that because there is more T and/or DHT in the blood, these hormones can now exert stronger inhibitory influences than prior to the use of chrysin. So the point here is that one way or another your body will figure out a way to regulate T levels.
End of Story
I hope that enough information has been presented to convince you that chrysin use doesn’t work like some speculate. Keep in mind these simple facts:
Several products didn’t even contain the label claim amounts of chrysin (if its not in there, it certainly won’t help),
It is most likely absorbed poorly and broken down in the gut by bacteria,
Metabolized by the liver into an excretable product bound to blood proteins which prevent it from doing anything,
May also inhibit insulin release, and
Over the long run may not raise T.
Let’s say you still are interested though, after all so many mags have written about it and so many companies sell it. Check this out, I have talked with about 100 different people who all claimed to have tried using chrysin. Reported dosages ranged from 1-4 grams per day. After they wasted their money, they all claimed no notable improvements and would not recommend it to their friends. No this was not a scientific study, and sure it can be dismissed as BS, but if it worked wouldn’t at least one person have had something positive to say? Save your money. If you do take it, please call me and let me know your results.
Chrysin: The Final Word
While the idea of chrysin working as an aromatase inhibitor may look appealing on paper, it is just not panning out in the real world. The fact that other flavonoids may function in the body as ergogens does not mean that chrysin would as well. To date no studies have shown any conclusive evidence that chrysin can work in animals or humans in vivo. In vitro evidence indicates that it may work, but when you are looking to put on muscle, you want to know that it has been proven to work in humans not a bunch of isolated cells. Since science does not support the contention that chrysin can work in humans, let’s look at anecdotal evidence. In personal communications with people that have tried chrysin, I have yet to find anyone reporting that they would recommend it. This means they tried chrysin by itself and found an ergogenic effect. Some people have told me of positive results using products that contained chrysin and other compounds (ie prohormones) but I could not exclude the fact that their results were most likely due to the other products.
References
Formica, JV and W Regelson. Review of the biology of quercetin and related bioflavanoids. Food and Chemical Toxicology. 33 (12):1061-1080, Dec 1995.
Kellis, JT and LE Vickery. Inhibition of human estrogen synthetase (aromatase) by flavones. Science. 225:1032-1034, September 7, 1984.
Conney, AH, MK Buening, et al. Regulation of human drug metabolism by dietary factors. Ciba Foundation Symposium. 76:147-167, 1980.
Hii, CS, and SL Howell. Effects of flavonoids on insulin secretion and 45Ca2+ handling in rat islets of Langerhans. Journal of Endocrinology. 107(1):1-8, October, 1985.
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