Some athletes say that methoxyisoflavone improves muscle mass gains from strength training without undesirable hormonal side effects.

Methoxyisoflavone is a recently developed supplement related to the flavonoid family. Only one preliminary human trial has tested its effects on body composition changes with exercise. Although results were promising, double-blind research is needed to confirm them.

Methoxyisoflavone is a member of the family flavonoids (isoflavones). In a U.S. Patent, the developers of this substance claim, based on preliminary animal research, that it possesses anabolic (muscle-building and bone-building) effects without the side effects seen with either androgenic (male) hormones or estrogenic (female) hormones.¹ A preliminary controlled trial found that strength-training athletes who took 800 mg per day of methoxyisoflavone for eight weeks experienced a significantly greater reduction in percentage body fat than those who took a placebo.² Double-blind research is needed to confirm these findings. The U.S. patent also claims methoxyisoflavone reduces appetite and lowers blood cholesterol levels. Whether this claim is true has not yet been demonstrated in published scientific research

Hormones with anabolic effects on muscle often have side effects that include Reference acne, male-pattern baldness, prostate enlargement, and lower high-density lipoprotein (HDL; “good”) Reference cholesterol. Whether methoxyisoflavone can cause these side effects has not been investigated.

Several substances similar to methoxyisoflavone are found in many plants and some foods, including soybeans. Whether methoxyisoflavone itself is found in nature is unknown.