Sex differences in systemic metabolites at four life stages: cohort study with repeated metabolomics

Abstract

Background Males experience higher rates of coronary heart disease (CHD) than females, but the circulating traits underpinning this difference are poorly understood. We examined sex differences in systemic metabolites measured at four life stages, spanning childhood to middle adulthood. Methods Data were from the Avon Longitudinal Study of Parents and Children (7727 offspring, 49% male; and 6500 parents, 29% male). Proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy from a targeted metabolomics platform was performed on EDTA-plasma or serum samples to quantify 229 systemic metabolites (including lipoprotein-subclass-specific lipids, pre-glycaemic factors, and inflammatory glycoprotein acetyls). Metabolites were measured in the same offspring once in childhood (mean age 8\xa0years), twice in adolescence (16\xa0years and 18\xa0years) and once in early adulthood (25\xa0years), and in their parents once in middle adulthood (50\xa0years). Linear regression models estimated differences in metabolites for males versus females on each occasion (serial cross-sectional associations). Results At 8\xa0years, total lipids in very-low-density lipoproteins (VLDL) were lower in males; levels were higher in males at 16\xa0years and higher still by 18\xa0years and 50\xa0years (among parents) for medium-or-larger subclasses. Larger sex differences at older ages were most pronounced for VLDL triglycerides—males had 0.19 standard deviations (SD) (95% CI\u2009=\u20090.12, 0.26) higher at 18\xa0years, 0.50 SD (95% CI\u2009=\u20090.42, 0.57) higher at 25\xa0years, and 0.62 SD (95% CI\u2009=\u20090.55, 0.68) higher at 50\xa0years. Low-density lipoprotein (LDL) cholesterol, apolipoprotein-B, and glycoprotein acetyls were generally lower in males across ages. The direction and magnitude of effects were largely unchanged when adjusting for body mass index measured at the time of metabolite assessment on each occasion. Conclusions Our results suggest that males begin to have higher VLDL triglyceride levels in adolescence, with larger sex differences at older ages. Sex differences in other CHD-relevant metabolites, including LDL cholesterol, show the opposite pattern with age, with higher levels among females. Such life course trends may inform causal analyses with clinical endpoints in specifying traits which underpin higher age-adjusted CHD rates commonly seen among males.