Do Children’s Growth Standards Need Refinement?

A new study adds to previous evidence that children’s body composition standards may need a closer look to make sure they reflect the ethnic diversity of American teenagers.

Nutritional researcher Ken Ellis conducted the study at the Children’s Nutrition Research Center in Houston. The center is a cooperative facility run by USDA’s Agricultural Research Service and Baylor College of Medicine.

Growth standards are often used to indicate a child’s nutritional status. But currently they refer only to age, gender and weight. The Houston study is the latest evidence that revising the standards to include body composition--the body’s ratio of fat, bone and lean muscle--might help pediatricians and parents assess more accurately whether a child is growing up healthy.

Of the 297 boys in the study, 145 were white, 78 black and 74 Hispanic. All were healthy and fit. Ages ranged from 3 to 18 years. The researchers said they owe a debt of gratitude to the boys’ parents for permitting their sons to participate in the voluntary study. Ellis used a noninvasive technique--dual-energy x-ray absorptiometry (DXA)--to compare the boys’ body composition at various ages.

The preliminary findings suggest black, white and Hispanic boys develop differences in body composition as they reach puberty. As children grow, their bone mineral and muscle tissue increase. They also store some fat to serve as an energy reserve to help fuel rapid growth during puberty. But Ellis found black teens in the study stored relatively more muscle and bone, and Hispanic teens stored relatively more fat. After accounting for height, weight, age and other factors, the scientists found significant differences in the boys’ growth patterns by ethnic group.

The study follows up on a similar one on girls at the Houston center. The earlier trial’s conclusions also indicated ethnic diversity should be considered in developing body composition standards. Other institutions are studying children’s growth standards such as the U.S. National Center for Health Statistics and the World Health Organization.

Scientific contact: Kenneth J. Ellis, USDA-ARS/Baylor College of Medicine, Body Composition Laboratory, Children’s Nutrition Research Center, Houston, Texas, phone (713) 798-7131, fax 798- 7130, kellis@bcm.tmc.edu