Methoxyisoflavone is not a nutrient and is not supplied to any meaningful extent in food. However, it is possible that, once in the body, natural isoflavones, such as daidzein, may be converted to some extent into methoxyisoflavone.
Methoxyisoflavone is marketed as an anabolic steroid, said to increase muscle mass without causing androgenic (testosterone-like) effects. However, there is no meaningful evidence that it actually works.
The use of methoxyisoflavone in the US began with two US patents established in the late 1970s.
The patent applications report a few research studies performed by the Hungarian pharmaceutical company Chinoin. None of these studies were published in peer-reviewed journals; furthermore, even as described, this research is altogether inadequate to demonstrate effectiveness, consisting as it did only of animal studies and exceedingly preliminary studies on humans. Proof of effectiveness is not required to establish a patent.
One placebo-controlled human trial on methoxyisoflavone was published in abstract form in 2001.
Apparently, this study found that athletes who took 800 mg per day of methoxyisoflavone for 8 weeks experienced a significantly greater increase in muscle mass than those who took placebo. However, despite claims made by methoxyisoflavone retailers, this study was not published in a prestigious journal. Rather, it appeared in what is a called a “supplement” published in association with a fairly prestigious journal. Supplements are special editions printed by a journal for extra income; they explicitly lack the supervision, approval, review or imprimatur of the journal itself. For this reason, all studies published in journal supplements must be taken with a grain of salt. This is particularly so in cases like this, where only an abstract of the study was published rather than the full text of the study itself.
Another oft-repeated claim regarding methoxyisoflavone is that it is widely utilized in the livestock industry to enhance lean mass. However, if livestock breeders are in fact using methoxyisoflavone, they are keeping it quiet: an Internet search for “methoxyflavone” and “livestock” turned up numerous sites that sell supplements to humans (and make this claim to support the sales of their product), but not a single site by or for livestock breeders.
The bottom line: There is no meaningful evidence to indicate that methoxyisoflavone is useful as a