Association of Acylcarnitine Species and Anthropometry Markers in a Population-Based Apparently Healthy Cohort

Background/Objectives: Acylcarnitine has been linked to adiposity, yet evidence in healthy adults is scarce. Hence, we aim to investigate associations of circulating acylcarnitine levels with traditional and newer anthropometric markers cross-sectionally, and with future weight change prospectively. Methods: We used data from CoLaus|PsyCoLaus cohort of apparently healthy adults in Lausanne, Switzerland. Anthropometry markers include body mass index, waist circumference, waist–hip ratio, conicity index, body roundness index, body shape index, leptin, adiponectin and grip strength. Results: Cross-sectionally, free carnitine, short-chain acylcarnitines (SCACs: C0, C3:0, C4:0 C5:0 and C5:0-OH), medium-chain acylcarnitines (MCACs: C6:0 and C8:1) and long-chain acylcarnitines (LCACs: C16:0) were positively associated with most anthropometric markers. After multivariate adjustment, only free carnitine, SCACs (C3:0 and C5:0), and MCAC C8:1 retained their positive associations with multiple markers. SCACs showed the strongest associations (−log10 p-values up to 91), followed by free carnitine and Deoxycarnitine. When stratified by sex, C8:1 showed consistent positive associations with anthropometric markers only in females. Prospectively, a higher baseline level of SCAC (C5:0-OH) was associated with ≥5 kg weight gain at both 5- and 10-year follow-ups, whereas higher baseline levels of MCAC (C8:1) and LCACs (C16:0 and C18:2) were associated with weight gain only at 10 years. Conclusions: SCAC showed most consistent associations with multiple anthropometric markers. Prospectively, specific ACs were associated with weight gain, suggesting that baseline AC levels may reflect early metabolic alterations linked to adiposity.