The effects of isoflavones combined with soy protein on lipid profiles, C-reactive protein and cardiovascular risk among postmenopausal Chinese women

Abstract

Background & Aims

Observational studies note that regular dietary soy protein intake (6–11 g day⁻¹) has a significant association with lower blood lipids; however, these observations have not been confirmed by clinical trials. This study aimed to ascertain the effects of moderate intake of soy protein (15 g) with isoflavones or isoflavones alone on serum lipid profiles, inflammatory markers (C-reactive protein and uric acid) and composite cardiovascular risk in Chinese postmenopausal, prediabetic women.

Methods and Results

A double-blind randomised, placebo-controlled trial was conducted among 180 postmenopausal Chinese women with prediabetes or early untreated diabetes, aged 46–70 years and, on average, 6.0 years since menopause. Participants were randomly assigned to one of the three arms to receive 15-g soy protein and 100-mg isoflavone (Soy group), or 15-g milk protein and 100 mg isoflavone (Iso group) or 15-g milk protein (placebo group) on a daily basis for 6 months. The results showed that no significant difference was observed in serum high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), triaclyglycerol (TG), high sensitive C-reactive protein and a composite 10-year cardiovascular risk between the three groups at both 3 and 6 months. Serum uric acid marginally increased by 1.22% in the Soy group and decreased by 4.28% and 4.82% in the Iso and placebo groups at 3 months (P = 0.087), but no difference was observed at 6 months (P = 0.264).

Conclusion

Soy protein with isoflavones or isoflavones alone at the provided dosage showed no significantly beneficial effects on measured cardiovascular risk factors in postmenopausal Chinese women with early hyperglycaemia.