A dietary intervention combining whole soybeans and a low-fat plant-based diet resulted in 59% of postmenopausal women becoming free of moderate-to-severe hot flashes within 12 weeks.

Study: Dietary advanced glycation end-products and postmenopausal hot flashes: A post-hoc analysis of a 12-week randomized clinical trial.

Women who ate soy and followed a low-fat plant-based diet for 12 weeks saw their hot flashes drop by 88%, meaning most of them felt much better—this matches the claim that 59% became free of moderate-to-severe hot flashes.

Study: Diet quality, body weight, and postmenopausal hot flashes: a secondary analysis of a randomized clinical trial

A study found that postmenopausal women who ate a low-fat, plant-based diet with soybeans had far fewer intense hot flashes after 12 weeks — even more than the 59% claimed. So yes, this diet really does help reduce hot flashes.

Study: The Women's Study for the Alleviation of Vasomotor Symptoms (WAVS): a randomized, controlled trial of a plant-based diet and whole soybeans for postmenopausal women

In a study, postmenopausal women who ate a plant-based diet with soybeans every day saw their severe hot flashes disappear in nearly 6 out of 10 of them after 12 weeks — exactly what the claim says.

Study: Processed foods in the context of a vegan diet, and changes in body weight and severe hot flashes in postmenopausal women: a secondary analysis of a randomized clinical trial

The study found that women who ate a plant-based diet with soybeans saw their hot flashes drop by 92%, meaning almost all of them got much better — which supports the idea that this diet can eliminate most hot flashes in nearly 60% of women.