Associations between dietary and circulating phytosterols and cardiovascular disease risk biomarkers in a Manitoba adult cohort
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Cardiovascular disease (CVD) is a leading cause of death worldwide. Elevated serum lipid levels and increased arterial stiffness are some of the risk factors responsible for the development of CVD. Phytosterols are well known for their cholesterol-lowering ability. Besides cholesterol-lowering, whether dietary phytosterols are beneficial for vascular function is not completely known yet. This thesis aimed to investigate the association between dietary and circulating phytosterols with serum lipid levels and arterial stiffness biomarkers, including blood pressure (BP), augmentation index (AIx), and pulse wave velocity (PWV). The secondary objective was to investigate the relationship of the Mediterranean-style dietary pattern scoring (MSDPS) with dietary phytosterols and its impact on CVD risk biomarkers. This cohort study on Manitoban adults included 157 men and 120 women, aged 30-46 years old. This study measured dietary and circulating phytosterols using 24-hour dietary recall and gas chromatography, respectively, and the MSDPS was used to evaluate the dietary pattern using the diet history questionnaire. Data were statistically analyzed using analysis of covariance, multiple linear regression and correlation. After adjustment for age, body mass index (BMI), total energy intake, fats as a percentage of energy intake, and dietary fiber, this study found that participants with high phytosterol intake (392.7±108.8 mg/d) in the highest quartile had 0.52 mmol/L (-10.2%) lower serum total cholesterol (TC) (P<0.05) and 0.47 mmol/L (-14.4%) lower (P<0.05) serum low-density lipoprotein cholesterol (LDL-C) than did the participants in the lowest quartile (97.7±36.5 mg/d). Phytosterol intake in the highest quartile showed a significant reduction in systolic BP (-5.3%, P<0.01), diastolic BP (-4.5%, P<0.01), and PWV (-3.4%, P<0.05) than those in the lowest quartile. The increased sitosterol-to-cholesterol ratio correlated with reduced serum TC, LDL-C, triglyceride, and diastolic BP, PWV (all P<0.001) and systolic BP (P<0.01) and increased high-density lipoprotein (P<0.01). A lower lathosterol-to-cholesterol ratio was correlated with decreased PWV (P<0.0001). No significant associations were found between MSDPS and the dietary phytosterols. The study results concluded that dietary phytosterol intake is associated with cholesterol-lowering and reduced arterial stiffness. Therefore, the present study suggests that increased intake of dietary phytosterols could help to reduce the risk of CVD.