Rickets has long been considered a Third World disease, not seen widely in the United States since poignant photos captured the bent and bowed legs of malnourished children during the Great Depression of the 1930s.
But this bone-deforming nutritional disorder, which health officials thought they’d eliminated with the fortification of baby formula and foods, has been on the rise in recent years among U.S. infants and toddlers. Most cases have been found in African American and Latino youngsters who are exclusively breast-fed for prolonged periods.
The federal Centers for Disease Control and Prevention has investigated cases in Georgia and in North Carolina, where Wake Forest University doctors in 2000 reported a fourfold increase in cases among African American babies and a threefold increase among all babies. In April, the American Academy of Pediatrics recommended that all infants, children and adolescents get at least 200 international units, or IU, of vitamin D daily.
“We see more nutritional rickets than ever before,” said Dr. Pisit Pitukcheewanont, a pediatric endocrinologist who directs the bone disorders program at Childrens Hospital Los Angeles. The increases aren’t huge -- Pitukcheewanont currently has 10 rickets patients and sees about two new cases each year -- but are particularly alarming because the condition was considered vanquished.
Children who develop the problem, usually diagnosed in the first two years of life, often have bone deformities as well as weakness and bone pain.
Unlike other forms of rickets that are hereditary or linked to liver and kidney disorders, nutritional rickets typically is associated with a deficiency in vitamin D. The deficiency stems either from a lack of the vitamin in the diet or insufficient exposure to sunlight, which helps the skin synthesize the vitamin.
When treated with large doses of vitamin D and calcium, rickets often can be cured, but some rare patients may require surgery and those who aren’t diagnosed early may face complications such as stunted growth and seizures.
The body needs vitamin D to regulate levels of calcium, which plays an important role in many body processes and regulates muscle function, nerve function and blood clotting. With too little vitamin D -- found in eggs, meat, green leafy vegetables, fish oil and fortified cereals -- the body becomes unable to absorb enough calcium to keep bones strong. The bones weaken, causing deformities of the legs, arms, spine, skull and chest, fractures, dental deformities and pain associated with rickets.
Darker-skinned children are more vulnerable to vitamin D deficiency -- and thus more susceptible to rickets -- because their pigmentation naturally filters out sunlight. But exposing them to more sun could raise their risk of skin cancer, posing a dilemma for doctors and parents trying to prevent the disease. Further complicating the problem is that sunscreens prevent vitamin D synthesis.
Benefits of sunlight
Pitukcheewanont believes that the benefit of “appropriate sun exposure outweighs the risk of skin cancer, especially in children,” and recommends at least 20 minutes of midday sun three times a week for children in Southern California. Although sunlight is the best natural source of vitamin D, parents seeking an alternative can give their children vitamin D supplements.
At King-Drew Medical Center in South Los Angeles, Dr. Robert Christiansen, a pediatric endocrinologist, said he’s been seeing two to three serious nutritional rickets cases annually in recent years, almost all among African American kids. “Most of the kids I see are developing it in the first eight months of life. The ones I see are the ones that get into trouble with very low calcium; their calcium goes down and they have a seizure.”
Rickets is most often diagnosed in babies who consume only breast milk for an extended period, because mother’s milk, while rich in protein, fat and other nutrients, is low in vitamin D. Although the amount may be sufficient for the early months of a baby’s life, breast milk can have even lower levels of the vitamin if the nursing mother is deficient herself in the vitamin, Pitukcheewanont said.
He said nursing women should have their vitamin D levels measured and be given vitamin D and calcium supplements if necessary.
Children who are breast-fed for longer than six months should have small amounts of baby cereal or other solid foods, or else take a supplement to ensure they’re getting enough of the vitamin, he said.
The American Academy of Pediatrics’ advice on supplementation includes a recommendation that all infants who are exclusively breast-fed receive 200 IU of daily vitamin D supplementation beginning at 2 months old to prevent the condition. (Rickets cases initially are treated with as much as 2,000 to 4,000 IU).
The nutritional disorder also is cropping up among young children whose families avoid dairy products, which typically are vitamin-D fortified. Those include youngsters fed soy and rice beverages in place of milk; those in strictly vegetarian families who don’t get sufficient calcium and vitamin D from dark, leafy greens and tofu; and children of lactose-intolerant mothers who fear their children may have inherited their inability to digest cow’s milk.
Low calcium also a culprit
But a lack of vitamin D is not the sole culprit for the increase in rickets.
A pediatric endocrinologist who specializes in bone disorders has found rickets among breast-fed children with normal stores of vitamin D who were weaned to diets low in calcium. Dr. Thomas O. Carpenter, a professor of pediatrics at Yale University, said these youngsters weren’t being fed milk, yogurt, cheese or other calcium-fortified products. Instead, they were drinking what older kids in the household were having, such as juices and sodas.
Carpenter and two Yale colleagues published their findings about the role of low dietary calcium in rickets in the August issue of the Journal of Clinical Endocrinology & Metabolism, based on records of 43 children with nutritional rickets seen at Yale from 1986 to 2002.
“What we’re hoping is that people will also look at calcium, not just vitamin D, as a factor in the diet of young children,” said Maria de Lucia, the study’s lead author and a former Yale research associate. “If you don’t get enough calcium in childhood and then in adolescence, you’re not building good bone mass.”