Association between plasma trans fatty acids and serum α-klotho levels in adults in the United States of America: an analysis of the NHANES 2009-2010 datasets

Background This study aimed to explore the potential associations between trans fatty acid (TFA) and alpha-klotho levels. Methods Datasets from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) were analysed for this study. Multivariable linear regression and restricted cubic spline (RCS) analyses were performed to examine the relationships between plasma TFA and serum alpha-klotho levels. Results A total of 1,205 participants were included, with a geometric mean (GM) of 803.60 (95% CI: 787.45, 820.00) pg/mL for serum alpha-klotho levels. RCS analysis revealed L-shaped relationships between TFA and alpha-klotho levels. The inflection points for palmitelaidic acid (PA), vaccinic acid (VA), elaidic acid (EA), and total TFA levels were 4.55, 20.50, 18.70, and 46.40 mu mol/L, respectively. Before reaching the inflection point, serum alpha-klotho levels were negatively correlated with plasma PA, VA, EA and total TFA levels, with beta values (95% CI) of -0.15 (-0.24, -0.06), -0.16 (-0.23, -0.09), -0.14 (-0.22, -0.05) and - 0.19 (-0.27, -0.11), respectively. Linolelaidic acid (LA) levels exhibited an inverse and linear association with alpha-klotho levels ( P-nonlinearity=0.167, P-overall<0.001). L-shaped relationships between TFA and alpha-klotho levels were also observed in the subgroups of participants who were aged < 65 years, were male, did not exercise, were ex-smokers, and were overweight/obese. Conclusions L-shaped correlations between plasma PA, VA, EA, and total TFA levels and serum alpha-klotho levels were observed among adults in the United States.