Dietary Total Isoflavone Intake Is Associated With Lower Systolic Blood Pressure: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

Abstract

The effect of dietary isoflavone intake on systolic blood pressure (SBP) has not been studied in a large community-based cohort inclusive of African Americans. We analyzed data from the year 20 exam of the Coronary Artery Risk Development in Young Adults (CARDIA) study, including medical history, physical exam and dietary intake surveys for 3,142 participants. Multivariable linear regression models controlled for age, sex, BMI, smoking, physical activity, and intakes of alcohol and total energy. Effect modification by race was tested. Overall, those with hypertension had a lower daily intake of total dietary isoflavones (2.2±5.2 vs. 4.1±11.7 mg/day; p-value <0.001). In fully adjusted models, the highest quartile of dietary isoflavone intake was associated with a 4.4 mmHg lower SBP on average compared with SBP for the lowest quartile. The relation between dietary isoflavone intake and SBP was more pronounced among African Americans, compared to Caucasians (p-for interaction <0.001). Greater dietary intake of isoflavones was independently associated with a lower SBP.

Flavanone Intake Is Inversely Associated with Risk of Incident Ischemic Stroke in the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

“…Proposed cardioprotective mechanisms for flavonoids include antioxidant and anti-inflammatory action, modulation of lipid metabolism and platelet function, and attenuation of hypertension (2). Consistent with proposed biological mechanisms, results from epidemiologic studies suggest a protective effect for flavonoids against cardiovascular disease mortality (1, 3, 4), incident coronary heart disease (5,6), and incident stroke (7), as well as other indicators of cardiovascular risk, such as arterial stiffness, incident hypertension, and type 2 diabetes (8)(9)(10)(11). Although dietary flavonoid research has progressed over the past decade, existing literature is limited by incomplete dietary flavonoid information and lack of geographic and racial/ethnic diversity of studied populations, especially in the context of incident stroke.…”

“…Regional disparities in stroke may be related to lower flavanone intake in residents of the Stroke Belt and Stroke Buckle. One published study addressed modification of the association between isoflavone intake and blood pressure by race, which suggests stimulation of endothelial nitric oxide synthase in the setting of relative nitric oxide deficiency as a potential mechanism to explain a stronger beneficial association between dietary isoflavone and blood pressure in black participants than in white participants (11). Other flavonoid subclasses have been implicated in nitric oxide modulation (40), but to our knowledge, no other studies in humans have been published that allow comparison of results.…”

“…The REGARDS 11 (REasons for Geographic and Racial Differences in Stroke) study is a national, biracial prospective cohort study designed to investigate racial and regional disparities in stroke. Using the USDAÕs expanded flavonoid database, the Provisional Flavonoid Addendum, and data from REGARDS, we evaluated the association between total flavonoid and flavonoid subclass intakes and incident acute ischemic stroke.…”

Consumption of animal and plant foods and risk of left ventricular diastolic dysfunction: the Bogalusa Heart Study

“…Dietary isoflavones, obtained through soy-based foods such as tofu and tempeh, independently associate with lower systolic BP and may exert their effects through endothelium-dependent vasodilation. 47 Soy protein is rich in arginine, an essential component of the nitric oxide pathway, which may help promote vasodilation. 48 Moreover, vegetables are rich in potassium, a micronutrient that has also been shown to reduce BP in randomized controlled trials.…”

Beneficial Effects of Isoflavones in the Kidney of Obese Rats Are Mediated by PPAR-Gamma Expression

“…Isoflavones have been found to be beneficial in a wide range of diseases and have beneficial effects on some physiological risk factors for chronic kidney disease, such as dyslipidemia [ 30 ], hypertension [ 31 ], DM [ 32 ], and obesity [ 33 ]. In vitro studies [ 34 , 35 , 36 ] have shown that isoflavones downregulate several proinflammatory mediators like tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-8, IL-1β, prostaglandin E2 (PGE2), monocyte chemoattractant protein-1, and intercellular adhesion molecule-1, or they upregulate anti-inflammatory cytokines like IL-10 [ 37 ].…”