Randomized controlled trial of the effects of soy protein containing isoflavones on vascular function in postmenopausal women.

Study answer

What this study found

Soy protein containing isoflavones did not improve vascular function overall in older postmenopausal women. In intention-to-treat analyses, the change in brachial artery flow-mediated dilation was not different from placebo, 0.37 (-1.48, 2.21), P=0.69. Blood pressure findings were mixed: systolic blood pressure favored soy in some analyses, including a difference in change of 4.34 (0.25, 8.42), P=0.04 in ITT and 5.55 (1.07, 10.02), P=0.02 per protocol, but diastolic blood pressure and flow-mediated dilation were not significantly improved. Adverse events were similar between groups, with…

Study & population

Double-blind randomized controlled trial in postmenopausal women aged 60 to 75 years enrolled through the breast cancer screening program in Utrecht, The Netherlands.

Intervention

Participants in the active arm took one daily serving of 36.5 g soy protein powder containing 25.6 g isoflavone-rich soy protein, providing 52 mg genistein, 41 mg daidzein, and 6 mg glycitein (aglycone weights), for 12 months.

Key limitation

The main vascular endpoint was null, and subgroup benefit, including possible effects in equol producers, could not be determined conclusively.

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Original abstract