Prospective Association Between Plasma Amino Acids and Multimorbidity in Older Adults

Background Some amino acids have been associated with aging-related disorders and risk of physical impairment. The aim of this study was to assess the association between plasma concentrations of 9 amino acids, including branched-chain and aromatic amino acids, and multimorbidity. Methods This research uses longitudinal data from the Seniors-ENRICA 2 study, a population-based cohort from Spain that comprises noninstitutionalized adults older than 65. Blood samples were extracted at baseline and after a follow-up period of 2 years for a total of 1 488 subjects. Participants' information was linked with electronic health records. Chronic diseases were grouped into a list of 60 mutually exclusive conditions. A quantitative measure of multimorbidity, weighting morbidities by their regression coefficients on physical functioning, was employed and ranged from 0 to 100. Generalized estimating equation models were used to explore the relationship between plasma amino acids and multimorbidity, adjusting for sociodemographics, socioeconomic status, and lifestyle behaviors. Results The mean age of participants at baseline was 73.6 (SD = 4.2) years, 49.6% were women. Higher concentrations of glutamine (coef. per mmol/l [95% confidence interval] = 10.1 [3.7, 16.6]), isoleucine (50.3 [21.7, 78.9]), and valine (15.5 [3.1, 28.0]) were significantly associated with higher multimorbidity scores, after adjusting for potential confounders. Body mass index could have influenced the relationship between isoleucine and multimorbidity (p = .016). Conclusions Amino acids could play a role in regulating aging-related diseases. Glutamine and branched-chain amino acids as isoleucine and valine are prospectively associated and could serve as risk markers for multimorbidity in older adults.