Associations among the plasma amino acid profile, obesity, and glucose metabolism in Japanese adults with normal glucose tolerance

Abstract

BackgroundAmino acids (AAs) are emerging as a new class of effective molecules in the etiology of obesity and diabetes mellitus. However, most investigations have focused on subjects with obesity and/or impaired glucose regulation; the possible involvement of AAs in the initial phase of glucose dysregulation remains poorly understood. Furthermore, little attention has been given to possible associations between the pattern/degree of fat deposition and the plasma AA profile. Our objective was therefore to determine the relationships between plasma AA concentrations and the type/degree of obesity and glucose regulation in Japanese adults with normal glucose tolerance.MethodsEighty-three subjects with normal glucose tolerance were classified as obese or nonobese and as visceral obesity or nonvisceral obesity. Correlations between the plasma levels of 23 AAs and somatometric measurements, visceral fat area (VFA), subcutaneous fat area (SFA), and 75-g oral glucose tolerance test results were analyzed.ResultsObesity or visceral obesity was associated with higher levels of branched-chain AAs (isoleucine, leucine, and valine), lysine, tryptophan, cystine, and glutamate but lower levels of asparagine, citrulline, glutamine, glycine, and serine (p < 0.04). Age- and gender-adjusted analyses indicated that VFA was positively correlated with tryptophan and glutamate levels, whereas VFA and SFA were negatively correlated with citrulline, glutamine, and glycine levels (p < 0.05). The fasting and 2-h plasma glucose levels or the homeostasis model assessment of insulin resistance were positively correlated with valine, glutamate, and tyrosine levels but negatively correlated with citrulline, glutamine, and glycine levels. The homeostasis model assessment for the β-cell function index was positively correlated with leucine, tryptophan, valine, and glutamate levels but negatively correlated with citrulline, glutamine, glycine, and serine levels (p < 0.05).ConclusionsThe present study identified specific associations between 10 AAs and the type/degree of obesity, and indices of glucose/insulin regulation, in Japanese adults with preserved glucose metabolism. With the growing concern about the increasing prevalence of obesity and diabetes, the possible roles of these AAs as early markers and/or precursors warrant further investigation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12986-015-0059-5) contains supplementary material, which is available to authorized users.

Changes in Plasma Metabolite Concentrations after a Low‐Glycemic Index Diet Intervention

“…Nevertheless, this may be partly explained by the fact that none of the study subjects had prediabetes or T2D and the prevalence of hypertension was low. Moreover, as visceral obesity has been previously associated with lower circulating levels of amino acids, such as glycine and serine, the study gives further support to the beneficial effect of the LGI diet on visceral obesity even after adjusting for changes in BW.…”

Consumption of Whey in Combination with Dairy Medium‐Chain Fatty Acids (MCFAs) may Reduce Lipid Storage due to Urinary Loss of Tricarboxylic Acid Cycle Intermediates and Increased Rates of MCFAs Oxidation

“…However, this was not the case in the present study as the plasma level of tyrosine was higher in the WH group as compared to CH groups after the intervention. Recent studies have shown a positive correlation between high levels of BCAAs and obesity, and between high levels of both BCAAs and aromatic amino acids and insulin resistance . This was not the case in our study, as no increase in insulin resistance or body weight was observed in WH or WL group .…”

BCAA Metabolism and Insulin Sensitivity – Dysregulated by Metabolic Status?

“…Another study assessed non‐diabetic Japanese subjects (both obese and non‐obese) for AA circulation, and correlations with adiposity revealed both total obesity and visceral obesity were correlated with plasma BCAA levels (along with several other AAs) . Yet of the three BCAAs, only valine was associated with HOMA‐IR . In a separate report, correlations of metabolites of non‐diabetic Japanese subjects found significant associations between BCAAs (as well as with aromatic AAs) with HOMAR‐IR when subjects were stratified for low (<1.6) versus high (>1.6) HOMA‐IR .…”

“…Lastly, the report identified that while protein intake was associated with select AAs (valine, tyrosine, phenylalanine, and glutamine), it was not associated with insulin resistance . Another study assessed non‐diabetic Japanese subjects (both obese and non‐obese) for AA circulation, and correlations with adiposity revealed both total obesity and visceral obesity were correlated with plasma BCAA levels (along with several other AAs) . Yet of the three BCAAs, only valine was associated with HOMA‐IR .…”