A randomized clinical trial found that a low-fat vegan diet including daily soybeans may reduce body weight and the frequency of severe hot flashes in postmenopausal women. The benefits were linked to reduced consumption of animal-derived foods, regardless of whether the replacement plant-based foods were processed.

The 12-week trial enrolled 84 women aged 40 to 65 years who reported at least two moderate-to-severe hot flashes per day. The participants were randomly assigned to either a vegan diet group or a control group that maintained their usual omnivorous diet. The vegan group followed a low-fat, plant-based regimen that included 0.5 cups of cooked soybeans daily. No instructions were given regarding processed food intake.

Hot flashes were recorded using a mobile application, and dietary intake was assessed at baseline and after 12 weeks using 3-day food records. Foods were classified by processing level using the NOVA system and categorized by source—animal or plant based. Body weight was measured with a self-calibrating digital scale.

At week 12, the vegan group lost an average of 3.6 kg compared with 0.2 kg in the control group. Severe hot flashes decreased by 92% in the vegan group (from 1.3 to 0.1 per day), with no statistically significant change in the control group.

Reduced intake of unprocessed or minimally processed animal foods in the vegan group (−106 g/day) was associated with weight loss (r = +0.45, P < .001) and fewer severe hot flashes (r = +0.31, P = .01). Intake of ultraprocessed animal-derived foods also declined by 60 g/day, correlating with weight loss (r = +0.43, P < .001), though the association with hot flashes was not statistically significant (r = +0.24, P = .07).

While the vegan group increased their consumption of both processed and unprocessed plant-based foods, there was no observed relationship between plant-based food processing level and changes in weight or hot flashes. The findings suggested that the key factor was the reduction in animal-based foods rather than the degree of food processing.

The study was designed to assess the impact of food type and processing level on health outcomes in a vegan diet. Researchers acknowledged limitations, including self-reported dietary records and a volunteer sample, which may have affected generalizability.

Nevertheless, the results supported the effectiveness of a soybean-supplemented vegan diet—regardless of food processing level—in promoting weight loss and reducing menopausal symptoms by displacing animal-derived foods.

Source: Menopause