Levels of circulatory branched-chain amino acids are associated with dietary regimen. A cross- sectional analysis

Background & aims: Higher levels of circulatory branched chain amino acids (BCAA, isoleucine, leucine, and valine) are associated with a higher risk of diabetes and cardiovascular diseases. Diet is the main source of BCAA, but previous studies have shown conflicting results on the influence of diet on circulatory BCAA concentration. We evaluated the association between BCAA concentration and diet in a large population-based sample. Methods Data from 2159 participants (58.2% women, mean age 53.4 ± 8.6years) was included. Dietary intake was assessed by questionnaire and included 91 individual foods and 15 different nutrients. BCAA concentrations were measured by stable isotope dilution liquid chromatography-mass spectrometry (LC-MS) assay. Results The circulatory BCAA levels were higher in men than in women (250.2 ± 45.2 vs. 207.9 ± 36.1, 136.0 ± 24.4 vs 106.3 ± 17.4, 63.6 ± 13.0 vs 48.1 ± 9.2 µmol/L, p < 0.001). BCAA levels were negatively associated with vegetal protein intake (multivariable-adjusted beta: -0.051 and − 0.063 for Isoleucine and Valine, respectively, p < 0.05) and dairy product (-0.037, -0.063 and − 0.038, respectively, p < 0.05) consumption. The opposite trend was observed for consumption of meat and meat-derived products, but the associations did not reach statistical significance. Of the 15 different nutrients, 13 showed a significant correlation with BCAA. Specifically, total protein, total carbohydrates, polysaccharides, saturated fat (SFA), and total fat all showed significant positive association with BCAA, while total fibre, monosaccharides, and calcium showed significant negative correlations with BCAA. Conclusions Levels of circulatory in humans are negatively associated with plant protein and positively associated with polysaccharides, total fat, and animal protein. The associations are gender specific.