Researchers reviewed medical records of 30 babies diagnosed with nutritional rickets between 1990 and 1999 at two medical centers in North Carolina.
All of the children were African-American, aged 5 months to 25 months, and all were breast-fed but did not receive vitamin D supplements.
Over half of the patients were seen in 1998 and the first half of 1999, giving the researchers the impression that the incidence has risen sharply.
At the time of diagnosis, most of the infants were growth retarded in both height and weight with nearly one-third being severely growth retarded. Many of the infants also had bow legs and bone fractures, common problems with untreated vitamin D deficiency.
Vitamin D comes from two sources: food and sunlight. Some of the best food sources are liver, egg yolks, and fish.
Researchers suggest that there are several possible causes for the rise of infant rickets:
The increasing proportion of women who breast-feed their babies. Although experts encourage Breastfeeding, the vitamin D content of breast milk depends on the mother having adequate levels of the vitamin.
Pediatricians may not be adequately prescribing vitamin supplements for infants, especially to those who are breast-fed.
Dark-skinned people are more prone to vitamin D deficiencies because dark skin requires more sunlight to manufacture vitamin D, but the researchers stress that rickets is completely preventable.
"We support Breastfeeding as the ideal nutrition for babies and children but recommend supplementation of all dark-skinned, breast-fed infants and children with 400 IU of vitamin D per day, starting at least by 2 months of age," the researchers conclude.
Many Breastfeeding advocates are justifiably defensive of any perceived defamation of Breastfeeding, and therefore disagree with the assertion that vitamin D supplementation is required in a breastfed baby. However addressing this issue, accompanying editorial states:
A second objection may actually derive from our very appropriate advocacy for human milk as a "perfect food." For some, the need for supplementation may imply nutritional inadequacy. As emphasized above, however, calciferol (vitamin D) is in no sense a nutrient, but rather the precursor of a steroid hormone that is not naturally present in any infant food. Classifying the antirachitic substance in cod liver oil as a vitamin was an unfortunate historical error that has become too ingrained to correct.
If one views calciferol in this light, then it is not necessary to consider human milk "deficient." Instead, the provision of supplemental calciferol can be looked on as ensuring an adequate substrate for a hormone whose normal production has been adversely affected by the realities of modern living conditions. Human milk is, indeed, the "perfect food" for infants. Unfortunately, neither it nor any unsupplemented food or formula can prevent climate, latitude, smog, economic factors, or religious practices from coming between infants and sunshine.
Journal of Pediatrics August 2000; 137: 153-157.
This is an important article for me as it completely updated my view about vitamin D. I had always wondered why this was the ONLY vitamin that breast fed babies need (only if they are not regularly exposed to sunshine). The answer is that Vitamin D is NOT a vitamin but a steroid hormone precursor that is NOT naturally present in food. This explains why the most perfect food on the planet for humans, human breast milk, is "deficient" in vitamin D.
Vitamin D is one of the only supplements that a breast-fed baby will need, but this is only if the baby is not exposed to sunshine. The darker the skin of the baby the more sun exposure will be required for the baby to generate enough vitamin D. Even if the child does not develop rickets, less than optimal bone development and other problems will occur without adequate vitamin D. Typically parents are so concerned about calcium for proper bone growth and health, but in most cases the vitamin D is far more important.
Certain drugs have also been shown to interfere with vitamin D absorption and metabolism, including cholestyramine (Questran), Dilantin, and phenobarbital.
Additionally, because vitamin D is a fat-soluble vitamin, any drug or substance that interferes with fat absorption may cause problems, as may a low-fat diet.
A much less common type of rickets is caused by phosphate depletion and was reported on previously in the newsletter.