Food selection based on high total antioxidant capacity improves endothelial function in a low cardiovascular risk population.

BACKGROUND AND AIMS: Oxidative stress has been advocated as a major cause for cardiovascular disease (CVD), and low plasma antioxidant concentrations are associated with endothelial dysfunction, the first step towards atherosclerosis. However, although the antioxidant content in fruits and vegetables may explain at least in part their protective effect against CVD, supplementation with antioxidant vitamins fails to improve endothelial function and reduce CVD risk. The aim of this study was to investigate the impact of a diet rich in antioxidants on endothelial function measured by flow-mediated dilatation (FMD) in volunteers at low cardiovascular risk. METHODS AND RESULTS: In a crossover trial, 24 subjects (13 women, mean age 61 ± 3 years), received, in a randomised order, a 14-day high (HT) and a 14-day low (LT) antioxidant diets, with a 2-week wash-out (WO) in between. Both diets were comparable in daily portions of fruits and vegetables, and in alcohol, fibre and macronutrient intake, but differed in their total antioxidant capacity. Before and after each diet, anthropometrics, blood pressure, fasting plasma glucose, lipid profile, hepatic enzymes, circulating antioxidant concentrations, high sensitivity C-reactive protein (hs-CRP) and FMD were assessed. FMD increased significantly during the HT diet compared to the LT (p < 0.000). FMD values were 2.3% higher after HT compared with LT (p < 0.001) after adjustment for age, gender and diet order. α-tocopherol increased significantly (p < 0.05) and hs-CRP and of γ-glutamyltranspeptidase decreased significantly (p < 0.05 and p < 0.01, respectively) during the HT diet, compared with the LT diet. CONCLUSIONS: A short-term HT diet improves endothelial function in volunteers at low cardiovascular risk, which may further reduce their risk of CVD.

Intake of the plant lignans matairesinol, secoisolariciresinol, pinoresinol, and lariciresinol in relation to vascular inflammation and endothelial dysfunction in middle age-elderly men and post-menopausal women living in Northern Italy.

BACKGROUND AND AIMS: It has been suggested that lignan intake may decrease the risk for cardiovascular disease (CVD) by modifying traditional risk factors as well as aortic stiffness. However, the role of dietary lignans on the vascular system is largely unknown. The objective was to investigate whether dietary intake of plant lignans in a free-living population was associated with markers of vascular inflammation and function. METHODS AND RESULTS: We performed a cross-sectional study in 242 (151 males) men and post-menopausal women. Anthropometric characteristics and lignan intake were evaluated. Soluble intercellular adhesion molecule-1 (sICAM-1), insulin, high-sensitive C-reactive protein, glucose, total cholesterol, HDL-cholesterol and triacylglycerols were measured in fasting blood samples. Brachial flow-mediated dilation (FMD) measurements were available for 101 subjects (56 males). Median (interquartile range) daily intake of matairesinol (MAT), secoisolariciresinol (SECO), pinoresinol (PINO), lariciresinol (LARI), and total lignans was 20.9 microg (17.4), 335.3 microg (289.1), 96.7 microg (91.1), 175.7 microg (135.8), and 665.5 microg (413.7), respectively, as assessed by 3-day weighed food record. Plasma concentrations of sICAM-1 (whole sample) significantly decreased (mean (95%CI) = 358 microg/L (320-401), 276 microg/L (252-303), 298 microg/L (271-326), and 269 microg/L (239-303), P per trend 0.013) and FMD values (FMD sub-group) significantly increased (4.1% (2.2-6.0), 5.7% (4.3-7.2), 6.4% (4.9-7.8), and 8.1% (6.3-10.0), P per trend 0.016) across quartiles of energy-adjusted MAT intake, even after adjustment for relevant clinical and dietary variables. Intake of SECO was also inversely related to plasma sICAM-1 (P per trend 0.018), but not to FMD values. No relationship between intake of PINO, LARI or total lignans and either sICAM-1 or FMD values was observed. CONCLUSIONS: Higher MAT intakes in the context of a typical Northern Italian diet are associated to lower vascular inflammation and endothelial dysfunction, which could have some implications in CVD prevention.

Intervention study with a high or low antioxidant capacity diet: effects on circulating beta-carotene.

BACKGROUND AND OBJECTIVES: A cross-sectional observation suggests that total antioxidant capacity (TAC) of the diet positively affects plasma concentrations of beta-carotene independent of beta-carotene intake. This study was carried out to investigate the effect of two dietary strategies, designed to be comparable in fruits, vegetables, fibre, alcohol and beta-carotene intake but substantially different in their TAC, on changes in antioxidant intake and antioxidant status, and in particular in circulating beta-carotene concentrations. SUBJECTS: A randomized cross-over intervention trial involving 33 healthy participants and consisting of two 14-day dietary periods (high TAC diet, HT; low TAC diet, LT) with a 14-day washout in between was conducted. RESULTS: Energy, macronutrient, dietary fibre, alcohol and beta-carotene intake was not significantly different between LT and HT, whereas intake of other carotenoids and dietary TAC was significantly higher in the HT than in the LT (P<0.001). Circulating carotenoids (with the exception of alpha-carotene, which followed an inverse trend) and alpha-tocopherol decreased significantly during the LT and increased during the HT period. Among these, beta-carotene almost doubled its concentration in plasma after the HT diet. CONCLUSIONS: The increase in circulating beta-carotene along with the increase in dietary TAC suggests that plasma beta-carotene could be a marker of TAC intake rather than of beta-carotene intake itself. This may explain, in part, why beta-carotene supplementation alone has shown no benefit in chronic disease prevention and adds to a putative beneficial role of high dietary TAC diets, which merits further investigation.

The total antioxidant capacity of the diet is an independent predictor of plasma beta-carotene.

OBJECTIVE: To investigate the contribution of the total antioxidant capacity (TAC) of the diet to plasma concentrations of beta-carotene. DESIGN: Cross-sectional study. SETTING: Department of Public Health and Department of Internal Medicine and Biomedical Sciences, University of Parma. SUBJECTS: A total of 247 apparently healthy adult men (n=140) and women (n=107). METHODS: A medical history, a physical exam including height, weight, waist circumference and blood pressure measurements, a fasting blood draw, an oral glucose tolerance test and a 3-day food record. RESULTS: We observe a negative trend across quartiles of plasma beta-carotene for most biological variables clustering in the insulin resistance syndrome, as well as for traditional and new risk factors for type II diabetes and cardiovascular disease (CVD), including C-reactive protein and gamma-glutamyltranspeptidase (P<0.05). Regarding dietary characteristics, energy-adjusted intake of fat, fiber, fruits, vegetables, beta-carotene, vitamin C, vitamin E and dietary TAC significantly increased with increasing plasma beta-carotene (P<0.05), whereas alcohol intake decreased (P=0.013). Adjusted geometric means (95% confidence interval) of plasma beta-carotene significantly increased across quartiles of dietary TAC, even when single dietary antioxidants were considered in the model (QI=0.087 mg/dl (0.073-0.102); QII=0.087 mg/dl (0.075-0.103); QIII=0.114 mg/dl (0.098-0.132) and QIV=0.110 mg/dl (0.093-0.130); P for linear trend=0.026). When the population was divided on the basis of alcohol consumption, this trend was also observed in subjects drinking <20 g alcohol/day (P=0.034), but not in those with higher alcohol intake (P=0.448). CONCLUSIONS: Dietary TAC is an independent predictor of plasma beta-carotene, especially in moderate alcohol drinkers. This may explain, at least in part, the inverse relationship observed between plasma beta-carotene and risk of chronic diseases associated to high levels of oxidative stress (i.e., diabetes and CVD), as well as the failure of beta-carotene supplements alone in reducing such risk.