Key Findings
In this early research study, the correlation between habitually lower phytoestrogen intake in relation to cardiovascular risk factors in men aged 47 to 80 y enrolled in the Health Professionals Follow-up Study (HPFS) was assessed. The study indicates that usual intakes of isoflavones in U.S. men are not strongly associated with a beneficial cardiovascular risk profile. Furthermore, a diet high in lignans, even in the relatively low range of U.S. consumption, might be associated with increased LDL-C and apoB, and with reduced fasting insulin and insulin secretion.
ABSTRACT
Isoflavone supplementation in the form of soy protein-containing isoflavones is associated with beneficial lipid changes. Information on usual isoflavone and lignan intakes in the diet of Western men and their associations with cardiovascular risk factors is not available. From the Health Professionals Follow-up Study, we selected 468 men, aged 47-83 y, who were free of cardiovascular disease, diabetes, and cancer, and who had provided a blood sample in 1994. We measured circulating total, LDL, and HDL cholesterol, triacylglycerol, lipoprotein(a), apolipoprotein (apo) A1, apoB, hemoglobin (Hb)A1c, insulin, C-peptide, and leptin concentrations. Isoflavone and lignan intakes were calculated from a FFQ. We used multivariate linear regression. None of the cardiovascular risk factors was strongly associated with isoflavone intake. Blood levels of LDL cholesterol and apoB tended to increase with increasing lignan intake [for LDL cholesterol, quartile 4 -quartile 1 = 9% (95% CI 1%; 16%), P for trend = 0.01, and for apo B, quartile 4 -quartile 1 = 9% (95% CI 1%; 16%), P for trend = 0.02]. Fasting insulin and C-peptide tended to decrease with increasing lignan intake [for insulin, quartile 4 -quartile 1 = -11% (95% CI -55%; -8%), P for trend = 0.02, and for C-peptide, quartile 4 -quartile 1 = -25% (95% CI -44; -6%), P for trend = 0.01]. Our results suggest that intake of isoflavones within the range of Western diets is not associated with a cardiovascular risk profile among men. Diets high in lignan intake may increase apoB-containing lipoproteins and decrease fasting insulin secretion, but these findings require confirmation.