Is relative leg length a biomarker of childhood nutrition? Long-term follow-up of the Hyderabad Nutrition Trial.

BACKGROUND: Relative leg length is frequently used as a biomarker of childhood nutrition in epidemiological studies, but evidence is lacking. We examined the association between supplemental nutrition in pregnancy and childhood and relative proportions of components of height in adolescence. METHODS: In a community trial of nutritional supplementation, villages from adjacent administrative areas were selected to serve as intervention (n = 15) and control (n = 14) arms. In the intervention villages, balanced protein-calorie supplementation (2.51 MJ, 20 g protein) was offered daily to pregnant women and their offspring until the age of 6 years. Children born in the trial were re-examined 15 years later to assess components of height. RESULTS: A total of 1165 adolescents (intervention: 654, 49% of trial participants; control: 511, 41% of trial participants) aged 13-18 years were examined. Supplemented children were 10 mm taller [95% confidence interval (CI): 1.4 to 18.7 mm], but almost all of the increase was in trunk length (9 mm, 95% CI: 2.6 to 15.4 mm). The age- and gender-adjusted β-coefficients for the association of nutritional supplementation with relative trunk, leg and lower leg lengths (expressed as standard deviation scores) were 0.26 (95% CI: 0.11 to 0.42), 0.08 (95% CI: -0.03 to 0.19) and 0.03 (95% CI: -0.08 to 0.15) respectively, thereby unsupportive of cephalocaudal gradient in growth. CONCLUSIONS: In this nutritional supplementation trial in an undernourished population, we were unable to confirm relative leg length as a biomarker of childhood nutrition. Alternative explanations may underlie the reported associations between childhood conditions and relative leg length.