Effects of the Optimal Macro-Nutrient Intake to Prevent Heart Disease (OmniHeart) diets on urinary excretion profiles

Background: OmniHeart diets are diets rich in fruit, vegetables, and low-fat diary food with varying amount of carbohydrate, protein and unsaturated fat. These diets have been shown to reduce blood pressure, low-density lipoprotein cholesterol and coronary heart disease risk. However, the biological mechanism for this is unclear.

Objective: The aim of this study is to evaluate the effects of OmniHeart diets on the urinary profiles by proton nuclear magnetic resonance (1H NMR).

Methods: 158 men and women, aged 30 years and older, with prehypertension or stage 1 hypertension, each consumed three different OmniHeart diets for six weeks: a carbohydrate-rich diet (Carb, similar to the Dietary Approaches to Stop Hypertension, DASH diet); a protein-rich diet with protein predominantly from plant sources (Prot); and an unsaturated fat-rich diet mainly using monounsaturated fat (Unsat). All participants provided urine specimens at baseline (on a typical ‘American’ diet), and at the end of each dietary intervention. Spectra were acquired using a standard one dimensional experiment. Pairwise multilevel orthogonal partial least squares-discriminant analysis (OPLS-DA) comparison were made between baseline and each dietary intervention.

Results: All three multilevel OPLS-DA models showed clear separation between baseline and different OmniHeart diets, with model predictability (Q2Yhat) between 75 - 85 %. The urine 1H NMR spectra for OmniHeart diets were characterised by the higher concentrations of several metabolites of both exogenous and endogenous origin, as well as those derived from gut microbiota. Core molecules common to all three OmniHeart diets were also observed. The baseline urine spectra were characterised by the higher concentrations of molecules present in the aliphatic regions of the urine 1H NMR spectra.

Conclusion: NMR-based metabolic phenotyping approach provides an objective method for assessing the impact of different healthy diets in human population. It has the potential to delineate the complexities of dietary effect on human health. Future work aims to determine the identity of these discriminating molecules and to possibly un-cover the biological mechanisms of how these molecules may contribute the reduction of cardiovascular risk.