Chutamat Niwat

Effects of chronic and acute consumption of fruit- and vegetable-puree-based drinks on vasodilation, risk factors for CVD and the response as a result of the eNOS G298T polymorphism.

The average UK adult consumes less than three portions of fruit and vegetables daily, despite evidence to suggest that consuming five portions daily could help prevent chronic diseases. It is recommended that fruit juice should only count as one of these portions, as juicing removes fibre and releases sugars. However, fruit juices contain beneficial compounds such as vitamin C and flavonoids and could be a useful source of dietary phytochemicals. Two randomised controlled cross-over intervention studies investigating the effects of chronic and acute consumption of commercially-available fruit- and vegetable-puree-based drinks (FVPD) on bioavailability, antioxidant status and CVD risk factors are described. Blood and urine samples were collected during both studies and vascular tone was measured using laser Doppler imaging. In the chronic intervention study FVPD consumption was found to significantly increase dietary carotenoids (P=0.001) and vitamin C (P=0.003). Plasma carotenoids were increased (P=0.001), but the increase in plasma vitamin C was not significant. There were no significant effects on oxidative stress, antioxidant status and other CVD risk factors. In the acute intervention study FVPD were found to increase total plasma nitrate and nitrite (P=0.001) and plasma vitamin C (P=0.002). There was no effect on plasma lipids or uric acid, but there was a lower glucose and insulin peak concentration after consumption of the FVPD compared with the sugar-matched control. There was a trend towards increased vasodilation following both chronic and acute FVPD consumption. All volunteers were retrospectively genotyped for the eNOS G298T polymorphism and the effect of genotype on the measurements is discussed. Overall, there was a non-significant trend towards increased endothelium-dependent vasodilation following both acute and chronic FVPD consumption. However, there was a significant time x treatment effect (P<0.05) of acute FVPD consumption in individuals with the GG variant of the eNOS gene.

The Glu298Asp single nucleotide polymorphism in the endothelial nitric oxide synthase gene differentially affects the vascular response to acute consumption of fruit and vegetable puree based drinks

SCOPE Diets low in fruits and vegetables (FV) are responsible for 2.7 million deaths from cardiovascular diseases (CVD) and certain cancers annually. Many FV and their juices contain flavonoids, some of which increase endothelial nitric oxide synthase (eNOS) activity. A single nucleotide polymorphism in the eNOS gene, where thymine (T) replaces guanine (G) at position 894 predicting substitution of glutamate for aspartate at codon 298 (Glu298Asp), has been associated with increased CVD risk due to effects on nitric oxide synthesis and subsequently vascular reactivity. Individuals can be homozygous for guanine (GG), thymine (TT) or heterozygous (GT). METHODS AND RESULTS We investigated the effects of acute ingestion of a FV-puree-based-drink (FVPD) on vasodilation and antioxidant status in subjects retrospectively genotyped for this polymorphism. Healthy volunteers (n = 24; 11 GG, 11 GT, 2 TT) aged 30-70 were recruited to a randomized, controlled, crossover, acute study. We showed that acute consumption of 400 mL FVPD differentially affected individuals depending on their genotype. There was a significant genotype interaction for endothelium-dependent vasodilation measured by laser Doppler imaging with iontophoresis (P < 0.05) and ex vivo low-density lipoproteins (LDL) oxidation (P = 0.002). GG subjects had increased endothelium-dependent vasodilation 180 min (P = 0.028) and reduced ex vivo LDL oxidation (P = 0.013) after 60 min after FVPD compared with control, no differences were observed in GT subjects. CONCLUSION eNOS Glu298Asp genotype differentially affects vasodilation and ex vivo LDL oxidation after consumption of FV in the form of a puree-based drink.

Effects of acute consumption of fruit- and vegetable-puree-based-drink on plasma antioxidant status and flavonoid metabolites

Current recommendations suggest that a daily intake of 400g fruit and vegetables is required for the prevention of chronic diseases. Fruit and vegetables in the form of puree-based-drinks still contain vitamins, fibre, carotenoids, S compounds and organic acids, which contribute to health effects, but they also contain a wide variety of phenolic phytochemicals, which are increasingly recognised as effective against oxidative stress. Since 1974 there has been a constant increase in fruit juice consumption in the UK, from 30g per person per week in 1974 to 284g per person per week in 1999. In contrast, the general consumption of vegetables has remained reasonably constant and there has been a modest increase in fruit consumption. Thus, juice products may be a potentially-useful source of beneficial dietary phytochemicals.

The consumption of fruit juice rich in flavonoids increases plasma antioxidant status

Fruits and vegetables rich in flavonoids have been related to the reduction in the incidence of CVD in several epidemiological studies. Flavonoids are a group of phenolic compounds with strong antioxidant activity. Thus, the protective effects of the flavonoids could be a result of their ability to scavenge reactive oxygen and nitrogen species, which are formed during intracellular oxidative stress. However, postprandial effects on antioxidant status after consumption of fruits and juices are controversial. In addition, very little is known about the amount of flavonoids absorbed from the diet and the reliability of plasma biomarkers. Consequently, the aim of the present study was to investigate the beneficial effects of an acute intervention with flavonoid-rich juices on markers of oxidative stress and cardiovascular risk factors.

Effect of acute intervention with flavonoid-rich juice on the plasma antioxidant capacity.

Epidemiological data provide evidence that consumption of a diet rich in fruit and vegetables is associated with a reduction in the incidence of CVD. One possible mechanism for the protective effect of fruits and vegetables is the antioxidant activity of several compounds, including vitamins, minerals, fibre and other phytochemicals. Flavonoids are a group of phenolic compounds with strong antioxidant activity that are present in fruits, vegetables and other plant foods and play a role in the reduction of the incidence of chronic diseases such as CVD. However, very little is known about the amount of flavonoids absorbed from the diet and the reliability of plasma biomarkers. The present study set out to investigate the pharmacokinetics of flavonoid uptake and the beneficial effect of an acute intervention with flavonoid-rich juices on markers of oxidative stress and cardiovascular risk factors.Lower blood folate levels have been associated with depression in several cross-sectional surveys, but longitudinal studies are needed to assess whether depression is a consequence or a cause of folate deficiency. The Southampton Women’s Survey (SWS) comprises a cohort of 12 500 non-pregnant women recruited from the general population between 1998 and 2002 who are being followed through subsequent pregnancies. The SWS has been shown to be broadly representative of the general population1. From March 2000 all 7210 women recruited into the study were asked to complete a GHQ12 questionnaire to assess depression and anxiety2. All women were asked to provide venous blood samples from which erythrocyte folate (RCF) was assayed using an Abbott microparticle enzyme immunoassay IMx-folate kit and an IMx analyzer. Consent was obtained from the women to access their general practitioner (GP) records to obtain evidence of incident depression over the 2-year period following the baseline interview. Complete GHQ12 data were provided by 7020 women (97%) and RCF measurements were obtained for 5051 (72%) of them. Among the 5051 women 1588 (31%) were identified as depressed at the baseline survey. Using Poisson regression modelling with RCF as a continuous variable it was found that RCF was inversely associated with the risk of depression. The prevalence ratio associated with an increase in RCF of 100 nmol/l was 0.985 (95% CI 0.974, 0.995; P=0.005); those with RCF levels <960 nmol/l were 14% more likely to be depressed than those with higher levels. The association was attenuated after adjustment for confounding factors (P=0.05) but still indicated that lower RCF levels were linked to depression (prevalence ratio 0.98 (95% CI 0.97, 1.00; P=0.05). Follow-up data were available for 3996 women whose RCF levels had been measured (79%). The 1264 women who were identified as depressed at baseline either from the GP notes or from the GHQ12 questionnaire were excluded. Of the remaining 2732 women 307 (11%) had an incident episode of depression recorded by their GP in the 2 years following baseline interview. In a Cox regression model no relationship between RCF and incident depression was identified; the unadjusted hazard ratio per 100 nmol/l increase in RCF was 0.99 (95% CI 0.96, 1.02; P=0.4) and the adjusted hazard ratio was 1.00 (95% CI 0.97, 1.03; P=0.9). The finding of an association between RCF and prevalence of depression in a cross-sectional analysis but not with incident depression during follow-up of the cohort indicates that lower RCF levels may be more a consequence than a cause of depression. However, a positive association with incident depression cannot be excluded as smaller numbers of women contributed to the follow-up than to the cross-sectional analysis. Nonetheless, the 95% CI associated with the hazard ratio indicates that even a 100 nmol/l increase in RCF would be unlikely to reduce the risk of depression by more than about 3%. Thus, the contribution of low folate status to depression appears modest, and folate supplementation to prevent depression does not seem warranted on the basis of these findings.