A randomized, placebo-controlled trial on the effects of soy protein containing isoflavones on quality of life in postmenopausal women

Objective: Postmenopausal estrogen decline is implicated in several age-related physical and psychological changes in women, including decreases in perceived quality of life (QoL). A number of trials with hormone therapy showed beneficial effects of the intervention on parameters of quality of life. However, because of known or suspected serious side-effects of conventional hormone therapy there is a need for alternatives. Design: We conducted a double-blind randomized placebo-controlled trial with soy protein, containing 52 mg genistein, 41 mg daidzein, and 6 mg glycitein (aglycone weights), or milk protein (placebo)daily for 1 year. For thistrial,we recruited 202 postmenopausalwomenaged60to75years. Results: At baseline and at final visit, participants filled in the Short Form of 36 questions (SF-36), the Questionnaire on Life Satisfaction Modules (QLS M ), and the Geriatric Depression Scale (GDS). For the placebo group scores on all dimensions of the SF-36 and the QLS M decreased during the intervention year, except for the dimension ‘‘role limitations caused by physical problems.’’ The soy group showed increases on two dimensions of the SF-36 (‘‘social functioning’’ and ‘‘role limitations caused by physical problems’’) and on one dimension of the QLS M . There were however no statistically significant differences in changes of scores between the two intervention groups. For the GDS similarly, no significant differences were found between the groups. Conclusion: In conclusion, the findings in this randomized trial do not support the presence of a marked effect of soy protein substitution on quality of life (health status, life satisfaction, and depression) in elderly postmenopausal women.