Adiponectin, leptin, the adiponectin/leptin ratio, and physical fitness in children and young adults

Adiponectin and leptin are two recently discovered hormones that have been linked to chronic disease. High levels of adiponectin are associated with a reduced risk of obesity, cardiovascular disease, and cancer. High levels of leptin are associated with increased risk of obesity, CVD, hypertension, prostate cancer, and diabetes. Obesity and chronic disease are highly prevalent among ethnic minorities in New York City, The Columbia BioMarkers Study was a cross-sectional study of children and young adults aged 3-20 years in ethnic minority neighborhoods for the purposes of identifying risk factors for adult chronic disease. My hypothesis was that among children from diverse ethnic backgrounds, those with greater physical fitness (measured as cardiovascular endurance) would have lower leptin and higher adiponectin levels and higher adiponectin/leptin (A/L) ratios, when adiposity, insulin, age, race/ethnicity, gender and other covariates were taken into account. I did not find a significant relationship between physical fitness and adiponectin or the A/L ratio. High leptin levels were associated with lower physical fitness, but that association was weaker after adjustment for BMI or BMI z-score and disappeared after adjustment for sum of skinfolds. High adiponectin levels and A/L ratios were associated with all measures of adiposity except the BMI z-score. Our findings leave open the possibility that, among predominantly Hispanic/Latino children, adiposity measured as the sum of skinfolds mediates the associations of physical fitness with adiponectin, the adiponectin/leptin ratio and leptin. Our findings also suggest that in this population the sum of skinfolds is more strongly associated with those hormone levels and physical fitness than are other measures of adiposity.