Soy took off less than one hot flush a day
Across 62 randomised trials in 6,653 women, plant oestrogens as a group came to 1.31 fewer hot flushes a day, and soy on its own less than that. Night sweats did not improve.
What the study found
Soy's own effect was 0.79 fewer hot flushes a day
Across 62 randomised trials in 6,653 women, plant oestrogens as a group came to 1.31 fewer hot flushes a day, and soy on its own accounted for less than that. Night sweats did not improve at all, and vaginal dryness improved slightly.
The caveat · 46 of 62 trials at high risk of bias
Forty-six of the 62 trials, three-quarters of them, carried a high risk of bias in three or more quality domains. Against a typical starting point of several flushes a day, four-fifths of one is a real change and a small one. The night-sweats interval is wide enough to rule out almost nothing.