Reduced-fat vegan diet plus daily soybeans: Foods with benefits for postmenopausal women

A dietary intervention consisting of a plant-based diet, minimal oils, and daily soybeans appears to have favourable effects on vasomotor symptoms and menopause-related quality of life, as reported in a study.

“The dietary intervention led to clinically important reductions in menopausal symptoms. Of particular note was the 88-percent reduction in moderate-to-severe vasomotor events among intervention-group participants, accompanied by weight loss and improvements in physical, psychosocial, and sexual domains,” according to the investigators.

How diet may ward off vasomotor symptoms can be explained by “the fact that in premenopausal women, increasing dietary fat increases circulating oestradiol concentrations, whereas dietary fibre reduces these concentrations, suggesting the possibility that chronic elevations of oestrogen levels during the reproductive years may increase vulnerability to vasomotor symptoms at menopause,” they pointed out. [Am J Clin Nutr 1991;54:520-525; Cancer 1995;76:2491-2496]

In the study, the investigators randomized 84 postmenopausal women who reported at least two moderate-to-severe hot flashes daily to undergo a dietary intervention (mean age 53.2 years) or to make no dietary changes (control; n=42, mean age 55.2 years) for 12 weeks.

Participants in the intervention group had to avoid animal-derived foods, minimize the use of oils and fatty foods (eg, nuts and avocados), and consume 1/2 cup (86 g) of cooked whole nongenetically modified soybeans daily. Both the intervention and the control group were instructed to use a mobile application to record hot flashes (frequency and severity). They also completed the Menopause-Specific Quality of Life (MENQOL) questionnaire to provide information regarding vasomotor, psychosocial, physical, and sexual symptoms.

At week 12, moderate-to-severe hot flashes in the intervention group decreased by 88 percent from baseline (p<0.001), which was significant when compared with a decrease of 34 percent for the control group (p<0.001 vs baseline; p<0.001 between-group comparison). [Menopause 2022;doi:10.1097/GME.0000000000002080]

Half of completers who followed the diet reported the complete absence of moderate-to-severe hot flashes by the end of the intervention. On the other hand, none in the control group achieved this outcome.

The investigators noted that the degree of improvement in hot flashes was associated with neither seasonality—such that cooler temperatures did not seem to have induced symptomatic improvement—nor equol production. Correlations were instead observed between the changes in hot flashes and that in body weight (p=0.002).

Finally, the intervention group experienced greater changes in the MENQOL vasomotor (p=0.004), physical (p=0.01), and sexual (p=0.03) domains compared with the control group.

“The present study extends the findings from the initial study cohort by providing a larger sample, ruling out seasonality in the reduction in vasomotor symptoms, and providing initial data regarding equol,” the investigators said. [Menopause 2021;28:1150-1156]

However, they admitted that the inclusion criteria required at least two moderate-to-severe vasomotor events per day, fewer than the seven to eight events recommended by the US Food and Drug Administration for therapeutic trials.

“The present study may therefore be more informative for women with less frequent events and less so for those with more frequent events. Nonetheless, a small subanalysis of women with ≥7 events/d suggested that effects may be similarly robust in this subpopulation,” the investigators said.