Association between dietary branched-chain amino acids and odds of depressive symptoms in adolescent girls: an observational study

Purpose This study aimed to investigate the possible association between branched-chain amino acids (BCAAs) and their individual components, including leucine, isoleucine and valine, and the odds of elevated depressive symptoms in the adolescent female population. Design/methodology/approach This cross-sectional study included 263 adolescent girls aged 15–18 years. Dietary intake data were assessed using a validated food frequency questionnaire, and depression scores were determined using the Depression Anxiety Stress Scale-21. Multivariable linear regression and logistic regression were used to examine associations between BCAA intake and depression scores. Findings The participants’ mean ± standard deviation age and body mass index were 16.2 ± 1.0 years and 22.3 ± 4.1 kg/m², respectively. The median (interquartile range) intakes of total BCAAs, leucine, isoleucine and valine were 14.9(11.4–18.8), 6.5(4.9–8.2), 3.7(2.9–4.8) and 4.6(3.5–5.7) (g/day), respectively. Total BCAA intake was inversely associated with depression score (ß = −0.05; 95%CI: −0.10, −0.01; p = 0.02). Leucine showed the strongest individual association (ß = −0.06; 95%CI: −0.10, −0.01; p = 0.01), followed by isoleucine (ß = −0.05; 95%CI: −0.10, −0.00; p = 0.03). Participants in the highest tertile of total BCAA intake had significantly lower odds of elevated depressive symptoms compared to the lowest tertile (OR = 0.30; 95%CI: 0.14–0.66; p-trend < 0.001). This inverse association was consistent across leucine (OR = 0.40; 95%CI: 0.19–0.85; p-trend = 0.02), isoleucine (OR = 0.34; 95%CI: 0.16–0.73; p-trend = 0.01) and valine (OR = 0.44; 95% CI: 0.21–0.92; p-trend = 0.03). Originality/value This is the first study in an Iranian population to examine dietary BCAAs and odds of depressive symptoms in adolescent girls. The authors found that higher dietary intake of BCAAs, particularly leucine and isoleucine, was associated with reduced odds of elevated depressive symptoms.