"D-mystifying" the prevention of nutritional rickets

Recent reports of nutritional rickets suggest that an increasing number of infants and small children are at risk for this "soft" bone disease, which can cause bowed legs, poor growth and narrow, "pigeon" chests.

But, according to children's nutrition experts, the most common cause of this bone-deforming disease -- vitamin D deficiency -- can easily be prevented.

"Vitamin D is an unusual vitamin because the body can make all it needs when the skin is exposed to reasonable amounts of sunlight," said Dr. Steven Abrams, a professor of pediatrics at Baylor College of Medicine who studies calcium and bone metabolism at the CNRC. "But, for many children, modern lifestyles and cultural factors limit sun exposure, which makes dietary vitamin D essential."

Often called the "sunshine vitamin," vitamin D is actually a hormone required for proper calcium absorption and bone mineralization. Without vitamin D, growing bones stay "soft," making them subject to painful bending that can lead to deformities.

According to Abrams, most recently reported cases of rickets have been in breastfed, African-American babies who have had limited time in the sun and were not receiving supplemental vitamin D.

Infants and children require 200 IU of vitamin D each day for proper bone development. Infant formulas are fortified with the necessary amount of vitamin D, but human milk has relatively low levels. As a result, the American Academy of Pediatrics recommends supplemental vitamin D for breastfed babies who might be at risk for rickets. Vitamin D supplementation is usually achieved by providing infants with a multi-vitamin drop that contains the vitamin.

Some experts in this area also advocate routine vitamin D supplementation for all breastfed babies.

"When sunshine exposure is adequate, human milk provides all the nutrition an infant needs for the first six months of life," Abrams said. "But, when sunshine exposure is limited, exclusively breast-fed infants need supplemental vitamin D."

Toddlers with limited exposure to sunlight and well-meaning parents who routinely give them unfortified soy or rice "milks" as a substitute for cow's milk can also developed nutritional rickets.

"The addition of vitamin D to cow's milk has been very successful in preventing nutritional rickets among children," Abrams said. "But when children don't drink milk and don't get much time in the sun, they need another good source of vitamin D in their diets."

Few foods are naturally good sources of vitamin D except fish like halibut, salmon, cod, and herring and eggs, although many foods are fortified with the vitamin. However, while federal law requires that milk contain 100 IU of vitamin D per cup, fortification of other dairy products like yogurt, ice cream and cheese is not required. To check for foods for vitamin D, inspect food labels. Vitamin D will appear on the Nutrition Facts panel if it has been added. In addition to milk and fortified soy beverages, some ready-to-eat cereals are also vitamin-D fortified.

"Preventing nutritional rickets is not difficult," Abrams said. "But, parents need to be mindful that children who don't spend much time outdoors need this essential vitamin in their diets."

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