Metabolic Phenotyping Objectively Captures Dietary Intake and Short-term Cardiovascular Disease Risk Responses Under an Inpatient Randomized Crossover Clinical Trial

BackgroundDiet is central to cardiovascular disease (CVD) prevention, yet free-living studies rarely capture what people eat at home or how closely they follow an assigned diet due to limitations in self-reporting. Short-term inpatient feeding studies, with all meals provided and supervised intake, allow direct assessment of the physiological effects of dietary patterns. Objectivesi) To compare the short-term effects of a UK-National Institute for Health and Care Excellence (NICE) aligned diet versus a Western-style diet on CVD risk factors, metabolic phenotypes and microbiome; ii) To evaluate whether urinary metabolic phenotyping can objectively classify dietary adherence in adults with increased CVD risk. MethodsIn a controlled inpatient randomized crossover trial, 18 adults at elevated CVD risk completed two 72 h isocaloric diets: NICE-compliant and Western-style. Repeated-measures MCCV-PLS-DA assessed NMR fasting serum and 24 h urine metabolomic phenotypes. Univariate analyses examined CVD markers, urinary metabolites, serum SCFAs, and gut microbial richness and -diversity. ResultsDiet modulated CVD risk markers, with the NICE compliant diet lowering systolic blood pressure and atherogenic lipid parameters, whereas the Western-style diet increased these measures (all q < 0.05). The Western-style diet reduced microbial richness and tended towards lower -diversity. Urinary metabolic phenotyping identified 27 discriminatory metabolites between the diets reflecting food intake. Most diet-linked metabolites diverged from baseline within 24 h; microbiome derived metabolites demonstrated early and sustained divergence across 72 h. The urinary MCCV-PLS-DA model extended from a previously published framework in healthy adults, robustly classified dietary adherence (Q2Y=0.96), and correctly predicted allocated dietary intervention at earlier timepoints (24-48 h). ConclusionsUrinary metabolic phenotyping offers a sensitive and non-invasive tool for objectively assessing dietary intake. Short-term adherence to contrasting dietary patterns produced rapid, diet-specific metabolic and microbial effect in individuals at elevated CVD risk and differentially impacted cardiovascular risk profiles. This trial was registered at the ISRCTN registry (https://www.isrctn.com/ISRCTN44705179).