Objective: Phytoestrogens have been postulated to protect against cardiovascular diseases, but few studies have focused on the effect of Western dietary phytoestrogen intake.
Methods and results: Four hundred three women with natural menopause either between 1987 and 1989 or between 1969 and 1979 were selected from the baseline data of the PROSPECT study (n=17 395). Isoflavone and lignan intake was calculated from a food-frequency questionnaire. Aortic stiffness was noninvasively assessed by pulse-wave velocity measurement of the aorta. Linear regression analysis was used. After adjustment for age, body mass index, smoking, physical activity, mean arterial pressure, follow-up time, energy intake, dietary fiber intake, glucose, and high density lipoprotein cholesterol, increasing dietary isoflavone intake was associated with decreased aortic stiffness: -0.51 m/s (95% CI -1.00 to -0.03, fourth versus first quartile, P for trend=0.07). Increasing dietary intake of lignans was also associated with decreased aortic pulse-wave velocity: -0.42 m/s (95% CI -0.93 to 0.11, fourth versus first quartile, P for trend=0.06). Results were most pronounced in older women: for isoflavones, -0.94 m/s (95% CI -1.65 to -0.22, P for trend=0.02), and for lignans, -0.80 m/s (95% CI -1.85 to -0.05), fourth versus first quartile.
Conclusions: The results of our study support the view that phytoestrogens have a protective effect on the risk of atherosclerosis and arterial degeneration through an effect on arterial walls, especially among older women.