Supplements may affect teens\' fitness

Blood levels of various micronutrients were correlated with how well teens performed in certain physical fitness tests, researchers in Spain found. Luis Gracia-Marco of the University of Zaragoza in Spain and colleagues used data from a larger, long-term research project involving thousands of volunteers ages 12-17 in cities scattered across Europe. Blood samples taken in one-third of the volunteers -- about 1,000 -- were tested for a variety of micronutrients, including hemoglobin, indicative of iron intake, soluble transferrin receptor, serum ferritin, retinol, vitamin C, beta-carotene, alpha-tocopherol, vitamin B6, cobalamin, holo-transcobalamin, plasma folate, folate and vitamin D. The volunteers\' physical fitness was assessed through a standing long jump test, which assesses lower-body muscular strength, and a 65-foot shuttle run test, which assesses cardiovascular fitness through maximal oxygen consumption. The study, published in the Journal of Applied Physiology, found blood levels of certain micronutrients were intimately connected with the volunteers\' performance on the physical fitness tests. For cardiorespiratory fitness, concentrations of hemoglobin, retinol, and vitamin C in males and beta-carotene and vitamin D in females was associated with maximal oxygen consumption. For muscular fitness, concentrations of hemoglobin, beta-carotene, retinol, and alpha-tocopherol in males and beta-carotene and vitamin D in females was associated with performing better on the standing long jump test, the study said.