Metabolic pathways linked to sarcopenia in the Bushehr Elderly Health Program: kynurenine, nicotinamide, B-vitamins, and sulfur amino acids

Sarcopenia, characterized by the loss of muscle mass and function, is a common condition in the elderly, associated with increased morbidity and mortality. Metabolic pathways, including the kynurenine, nicotinamide, B-vitamins, and sulfur amino acid pathways, may play a significant role in the development and progression of sarcopenia. This study investigates the relationship between metabolic pathways and sarcopenia, aiming to identify potential therapeutic targets. Four hundred participants over 60 years were randomly selected from the second stage of the Bushehr Elderly Health Program (BEH). Frozen plasma samples were used to measure metabolomics. We used factor analysis and logistic regression analysis to determine the kynurenine-tryptophan metabolites associated with sarcopenia and its components. Study participants included 89 sarcopenic subjects aged 72.92 ± 7.32 years and 307 non-sarcopenic subjects aged 68.12 ± 5.56 years. In full model adjustment, factor 3, which included methionine, tryptophan, 3-hydroxyanthranilic acid, picolinic acid, and xanthurenic acid, was associated with 38.3% lower risk of sarcopenia (OR = 0.617 [95%CI = 0.436–0.875]); Factor 6, which included methylmalonic acid and total homocysteine, was associated with a 33.7% increased risk of sarcopenia (OR = 1.337 [95%CI = 1.031–1.735]); and factor 7, consisting of nicotinamide, were related to a 25.2% lower risk of developing sarcopenia (OR = 0.748 [95%CI = 0.571–0.979]). Additionally, factor 1, which included quinolinic acid, kynurenine, 3-hydroxykynurenine, neopterin, kynurenic acid, anthranilic acid, cystathionine, and total cysteine, was linked to a 49.2% higher risk of low muscle strength, while factors 3 and 7 were associated with approximately a 24% decrease in risk of low muscle strength. Factors 5, consisting of serine and glycine, and factor 7 were related to 43% and 27.7% lower risk of low skeletal muscle index, respectively. While factor 6 was related to a 32.8% higher risk of low skeletal muscle index. Factor 1 was also related to a 32.9% higher risk of low walking speed, while factor 3 was related to a 28.5% lower risk of low walking speed. Specific metabolites from the kynurenine, nicotinamide, B-vitamin, and sulfur amino acid pathways are significantly associated with sarcopenia and its key parameters, such as muscle strength, skeletal muscle index, and walking speed. These findings suggest that metabolic profiling could offer valuable insights for early detection and targeted interventions for sarcopenia in elderly populations.