Methoxivone has powerful oestrogenic effect

Bodybuilding supplements containing methoxivone may have an exceptionally strong oestrogenic effect. Irish researchers at Queen’s University Belfast in Belfast, write about this in the September 2014 issue of Food Chemistry. They tested a methoxivone supplement in test tubes and observed an oestrogenic effect 130 times above the level that toxicologists regard as acceptable.

And to set the record straight from the start: the researchers are not 100 percent sure of their case. If you swallow substances, your body only partially absorbs them. In addition, substances undergo all sorts of transformations and they don’t reach all parts of your body.

Estradiol receptor
The Irish tests do not take these issues into account. The researchers exposed cells with estradiol receptors to the supplements, and then observed whether the cells received oestrogenic stimuli via the receptors, and that was that.

The researchers had already tested 116 sports supplements and found androgen activity in about half of them, and oestrogenic activity in eighty percent. [Anal Bioanal Chem. 2012 Jul;403(10):3057-67.] The Irish then attempted to measure the strength of the oestrogenic effect in some of the oestrogen supplements.

Oestrogenic activity
Toxicologists think that humans are safe if they consume the equivalent of 0-50 nanograms estradiol per kg bodyweight daily through their diet. The researchers discovered that thirteen supplements contained such high levels of oestrogenic ingredients that users would definitely exceed the limit.



The oestrogenic effect of supplement 12 is very strong indeed. The table below shows that this is 5-methyl-7-methoxy-isoflavone [structural formula shown on right], which also goes by the name methoxivone, and is sometimes found in bodybuilding supplements. Methoxivone is a synthetic compound, although supplements manufacturers sometimes say that it is found naturally in soya.

An interesting detail: according to the patents in which the manufacturers of methoxivone describe the effects of methoxivone on laboratory animals, the oestrogenic effect of methoxivone is nil.


The right-hand column of the table shows the oestrogenic effect in combination with small amounts of estradiol. What’s really, really strange is the oestrogenic effect of HMB that occurs suddenly.

Does the researchers’ measuring method hold water? You may well wonder…

The researchers themselves think that the effects they discovered must first be checked in new, reliable studies. But as long as these studies are not there, they think that males under 16 and post-menopausal women are probably better off not taking methoxivone. In the worst-case scenario a supplement containing methoxivone boosted oestrogenic activity in these two groups by 1200 and 2500 percent more respectively than the level that is normal for these groups.

Estrogenic endocrine disruptors present in sports supplements. A risk assessment for human health.


Sports supplements are becoming a regular dietary addition for consumers who view such products as a means of improving their health and performance. Previously estrogenic endocrine disruptors (EDs) were detected in 80% of 116 sports supplements investigated by biological in vitro reporter gene assays (RGAs). The aim of this study was to quantify the hormonal activity in 50 of these sports supplement samples using a validated estrogen RGA and perform an exposure and risk assessment for human health. Results showed that 17?-estradiol equivalent levels were higher than those reported as being present in the typical human omnivore diet in 33 of the sports supplements and higher than the acceptable daily intake (ADI) in 13 of these products. The highest activity samples presented a potential to influence the human daily exposure to 17?-estradiol like activity in various risk groups with a predicted hormonal impact of greatest concern in young boys and postmenopausal women. In conclusion, consumers of sports supplements may be exposed to high levels of estrogenic EDs.

PMID: 24767039 [PubMed – in process]

Source: http://www.ncbi.nlm.nih.gov/pubmed/24767039

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