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.