Mixed Results on Soy and Glucose Levels, Serum Lipids

HONG KONGSoy isoflavone supplementation might have a significant on fasting glucose in postmenopausal women, but it appeared to have no significant benefit to serum lipid levels, according to research published in Menopause (2007; 14(5):905-912).

Researchers from the University of Hong Kong conducted a double blind, randomized, placebo-controlled trial in 203 postmenopausal Chinese women aged 48 to 62 years. They randomly assigned the women to receive daily doses of 500 mg calcium, and zero isoflavones (placebo, n = 67), 40 mg isoflavones (n = 68), or 80 mg isoflavones (n = 68). Serum fasting glucose (FG), triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and total cholesterol were measured at baseline and one year after treatment. The primary data analysis was according to the intent-to-treat principle.

Results showed moderate, but significant, favorable effects of soy isoflavones on the changes and percentage of changes in FG. The one-year mean differences of FG changes were -5.2 mg/dL and -3.3 mg/dL in the 40- and 80-mg isoflavone groups, respectively, compared with the placebo group. There was also a significant interaction between the treatment and baseline FG on the changes in FG. The scientists noted isoflavone effects were much more significant in women with baseline FG 100 mg/dL or more than in those with FG less than 90 mg/dL. However, they observed little effect of soy isoflavones on changes in serum lipids among the treatment groups