Metabolome biomarkers linking dietary fibre intake with cardiometabolic effects: results from the Danish Diet, Cancer and Health-Next Generations MAX study.

Biomarkers associated with dietary fibre intake, as complements to traditional dietary assessment tools, may improve the understanding of its role in human health. Our aim was to discover metabolite biomarkers related to dietary fibre intake and investigate their association with cardiometabolic risk factors. We used data and samples from the Danish Diet Cancer and Health Next Generation (DCH-NG) MAX-study, a one-year observational study with evaluations at baseline, six and 12 months (n = 624, 55% female, mean age: 43 years, 1353 observations). Direct associations between fibre intake and plasma concentrations of 2,6-dihydroxybenzoic acid (2,6-DHBA) and indolepropionic acid were observed at the three time-points. Both metabolites showed an intraclass-correlation coefficient (ICC) > 0.50 and were associated with the self-reported intake of wholegrain cereals, and of fruits and vegetables, respectively. Other metabolites associated with dietary fibre intake were linolenoyl carnitine, 2-aminophenol, 3,4-DHBA, and proline betaine. Based on the metabolites associated with dietary fibre intake we calculated predicted values of fibre intake using a multivariate, machine-learning algorithm. Metabolomics-based predicted fibre, but not self-reported fibre values, showed negative associations with cardiometabolic risk factors (i.e. high sensitivity C-reactive protein, systolic and diastolic blood pressure, all FDR-adjusted p-values <0.05). Furthermore, different correlations with gut microbiota composition were observed. In conclusion, 2,6-DHBA and indolepropionic acid in plasma may better link dietary fibre intake with its metabolic effects than self-reported values. These metabolites may represent a novel class of biomarkers reflecting both dietary exposure and host and/or gut microbiota characteristics providing a read-out that is differentially related to cardiometabolic risk.

Effects of dietary saturated, monounsaturated, and n-3 fatty acids on blood pressure in healthy subjects.

BACKGROUND: The quantity and quality of fats consumed in the diet influence the risk of cardiovascular disease (CVD). Although the effect of diet on plasma lipids and lipoproteins is well documented, less information exists on the role of fats on blood pressure (BP). OBJECTIVE: The objective was to evaluate the effects of different types of dietary fat on BP in healthy subjects. DESIGN: Healthy subjects (n = 162) were randomly assigned for 3 mo to follow 1 of 2 isoenergetic diets: 1 rich in monounsaturated fatty acids (MUFA diet) and the other rich in saturated fatty acids (SFA diet). Each group was further randomly assigned to receive supplementation with fish oil (3.6 g n-3 fatty acids/d) or placebo. RESULTS: Systolic BP (SBP) and diastolic BP (DBP) decreased with the MUFA diet [-2.2% (P = 0.009) and -3.8% (P = 0.0001), respectively] but did not change with the SFA diet [-1.0% (P = 0.2084) and -1.1% (P = 0.2116)]. The MUFA diet caused a significantly lower DBP than did the SFA diet (P = 0.0475). Interestingly, the favorable effects of MUFA on DBP disappeared at a total fat intake above the median (>37% of energy). The addition of n-3 fatty acids influenced neither SBP nor DBP. CONCLUSIONS: Changing the proportions of dietary fat by decreasing SFAs and increasing MUFAs decreased diastolic BP. Interestingly, the beneficial effect on BP induced by fat quality was negated by the consumption of a high total fat intake. The addition of n-3 fatty acids to the diet had no significant effect on BP.

Dietary (n-3) fatty acids reduce plasma F2-isoprostanes but not prostaglandin F2alpha in healthy humans.

(n-3) Fatty acids are unsaturated and are therefore easily subject to oxidization; however, they have several beneficial health effects, which include protection against cardiovascular diseases. The aim of this study was to investigate whether (n-3) fatty acids, with a controlled fat quality in the background diet, affect nonenzymatic and enzymatic lipid peroxidation and antioxidant status in humans. A total of 162 men and women in a multicenter study (The KANWU study) were randomly assigned to a diet containing a high proportion of saturated fatty acids or monounsaturated fatty acids (MUFA) for 3 mo. Within each diet group, there was a second random assignment to supplementation with fish-oil capsules [3.6 g (n-3) fatty acids/d] or placebo. Biomarkers of nonenzymatic and enzymatic lipid peroxidation in vivo were determined by measuring 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) and prostaglandin F(2alpha) (PGF(2alpha)) concentrations in plasma at baseline and after 3 mo. Antioxidant status was determined by measuring plasma antioxidant capacity with an enhanced chemiluminescence assay. The plasma 8-iso-PGF(2alpha) concentration was significantly decreased after 3 mo of supplementation with (n-3) fatty acids (P = 0.015), whereas the PGF(2alpha) concentration was not affected. The antioxidant status was not affected by supplementation of (n-3) fatty acids, but was improved by the background diet with a high proportion of MUFA. We conclude that supplementation with (n-3) fatty acids decreases nonenzymatic free radical-catalyzed isoprostane formation, but does not affect cyclooxygenase-mediated prostaglandin formation.