Dietary genistein generates reduced blood pressure in female mice.

Cardiovascular disease is the leading cause of mortality in postmenopausal women in the US. Genistein is a naturally occurring phytoestrogen found in soy products. Studies have shown that intake of genistein (soy) may have beneficial cardiovascular health effects, however its underlying mechanism(s) of action are yet to be elucidated. We aimed to examine the effects of chronic exposure (1–2 months) to a genistein‐containing diet (600 mg/kg) and a genistein‐free diet (0 mg/kg) on vascular parameters in C57B1/6J female mice. We measured; aortic wall thickness from 6 μm slices of H & E stained aortic ring segments, weekly recordings of heart rate (HR) and mean arterial blood pressure (MAP), and assessment of cAMP and cGMP production from frozen aorta. We found no change in average aortic wall thickness in mice fed either a genistein‐containing diet (0.14±0.01 mm, n=10) or a genistein‐free diet (0.12±0.01 mm, n=10), however, luminal diameter was significantly increased in mice fed the genistein containing diet (genistein‐containing = 0.81±0.03 mm, (n=10) and genistein‐free = 0.62±0.02 mm (n=10), P<0.001). We found that MAP was significantly decreased in female mice fed a genistein‐containing diet (92.0±0.8 mmHg, n=8) compared to those on a genistein‐free diet (98.2±1.1 mmHg, n=11) between days 7–28. Furthermore, HR was unchanged in female mice fed either genistein‐containing or genistein‐free diet (689.9±9.0 beats/min (n=8) and 666.6±12.4 beats/min (n=11) respectively). In addition, total cAMP or cGMP levels in aorta were similar for female mice fed either diet. We conclude that dietary genistein significantly decreased MAP in female mice. This effect is likely not attributable to a change in either of the intracellular messengers cAMP or cGMP nor a change in aortic wall thickness but is potentially due to the vasodilatory effects of genistein.