Isoflavone supplementation and endothelial function in menopausal women

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Abstract
Despite strong observational evidence for a beneficial role of oestrogen in cardiovascular disease, recent trial results suggest that hormone replacement therapy (HRT) may have adverse effects in menopausal women with established coronary heart disease. Isoflavones are oestrogen analogues found in plants with oestrogen-like properties and, because of a favourable side-effect profile, may be ideal alternatives to HRT with respect to cardiovascular benefits. Endothelial function is a marker of cardiovascular health. We aimed to determine the effect of isoflavones on endothelial function using the brachial artery reactivity test. Twenty-nine healthy menopausal women underwent entry and exit brachial artery reactivity testing following randomization to 2 weeks of an oral soy isoflavone concentrate containing 80 mg of soy isoflavones (Archer Daniel Midland Inc., IL, USA) or placebo. At study exit, there was no difference between placebo and isoflavone groups with respect to flow-mediated dilation (%FMD(max)), change (entry to exit) in %FMD(max) or response to nitroglycerine (%TNG). Subgroup analyses assessing lipid and oestrogen effects did not produce any significant results. These results suggest that short-term oral isoflavone supplements do not improve endothelial function in healthy menopausal women.