CNRC experts 'D'-mystifies nutritional rickets

News that rickets is making a comeback has caused considerable concern for many parents. Yet, according to experts at the CNRC, the most common cause of this bone-deforming disease -- vitamin D deficiency -- can easily be prevented.

Rickets is a "soft-bone" disease that can stunt growth and make children bow-legged.

"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 Baylor professor of pediatrics who studies calcium and bone metabolism at the CNRC. "But, when modern lifestyles and cultural factors limit children’s sun exposure, dietary vitamin D becomes essential."

Often called the "sunshine vitamin," vitamin D is actually a hormone required for proper calcium absorption and bone mineralization.

Infants and children, as well as adults through age 50, require 200 IU of vitamin D each day. Infant formulas are fortified with the necessary amount, but human milk contains relatively little. As a result, the American Academy of Pediatrics recommends supplemental vitamin D, usually in the form of a multi-vitamin drop containing vitamin D, for breastfed babies who might be at risk for rickets. Some experts also advocate routine vitamin D supplementation for all breastfed babies.

"Human milk provides complete nutrition for the first six months of life, providing an infant’s exposure to sunshine is adequate," Abrams said. "But, when exposure is limited, exclusively breast-fed infants need supplemental vitamin D."

Although relatively rare, children and toddlers can also develop rickets.

"Preventing nutritional rickets is not difficult," Abrams said. "But, parents need to be aware of how their breastfed infants, and children who don’t spend much time outdoors, are obtaining vitamin D."

Vitamin D in food:

Few foods other than halibut, salmon, cod, and herring are naturally good sources of vitamin D. Although federal law requires that milk contain 400 IU of vitamin D per quart to help prevent rickets, this regulation does not apply to other dairy products like yogurt, ice cream and cheese, or to milk substitutes like soy and rice 'milk' beverages.

To check for vitamin D in foods, inspect food labels for the %DV of vitamin D,* which will only appear if this nutrient is present. In addition to milk and some soymilk beverages, several ready-to-eat cereals are fortified with vitamin D.

*The %DV for vitamin D is based on 400 IU. So, keep in mind that children need only half that amount.