Exercise and Phytoestrogens: a Synergistic Effect on Factors Predisposing to CVD in Postmenopausal Women

Menopause is characterized by a decrease of estrogen and progesterone levels and is associated with various changes in body composition, including an accumulation of total fat mass, a relocation of adiposity to the abdomen, deterioration of plasma lipid profile, increased risk of type 2 diabetes, and increased oxidative stress. Taken together, these changes increase the risk of developing cardiovascular disease (CVD).

Physical activity and hormone-replacement therapy (HRT) have been shown to act in synergy to improve total fat mass in postmenopausal (PM) women. Because the progesterone component of HRT has been associated with an increased CVD risk in older women with a family history of CVD, the use of HRT has become controversial. As a result, a large decrease of the use of HRT in the community has been observed and postmenopausal women (PM) have developed interest in alternative therapies. Among the possibilities, phytoestrogens have shown beneficial effects on menopausal symptoms and plasma lipids. Phytoestrogens are structurally and functionally similar to estradiol (the major estrogen in humans) but found only in plants such as soybean isoflavones. They do not exert any effect on breast cancer or/and endometrial tissue.

AIMS To examine the effects of phytoestrogens, exercise and the combination of both on lean body mass, total fat mass, visceral fat, blood lipid profile, oxidative stress markers, antioxidant system, glucose metabolism, and sex-hormone levels in obese PM women.

HYPOTHESES Women undergoing a combination of phytoestrogen treatment and an exercise program will display a greater increase in lean body mass, decrease in total and visceral fat mass, improvements in blood lipid profile, decrease in oxidative stress markers, increase in antioxidant system, improvement in glucose metabolism, and increase in sex-hormone levels than those submitted to any or one of the treatments.

A total of 120 women will be recruited. There will be 4 groups (30 women/group) undergoing exercise or not and supplemented with phytoestrogens or a placebo. The intervention is planned to last 12 mo. Key variables will be measured at baseline, and after 6 and 12 mo of intervention.

Three weekly 1h-sessions of exercise will be held on 3 non-consecutive days. The phytoestrogen supplements will consist of 70 mg/d of soy isoflavones taken as 4 caps/day.