Diet may be implicated in the observed rise of asthma and allergies in recent years. Multi-vitamin use, which is common among infants, may contribute to this trend. Milner and associates used the National Maternal and Infant Health Survey and a follow-up study to determine what effects multivitamin supplementation might have on the development of allergic conditions and asthma in infants.

The authors focused on patients who received supplements before six months of age, as well as those supplemented before three months of age. The outcome measures were asthma and food allergies, according to parental report of physician diagnosis.

Vitamin supplementation occurred in families with higher incomes and higher levels of maternal education. Asthma was reported to have been diagnosed in 851 (10.5 percent) of the respondents. A univariate analysis did not show a significant effect of multivitamin use on asthma, but when the study population was stratified according to race, a significant association occurred between supplementation during the first six months of life and increased asthma risk in black children, but not in non-black children.

Food allergies were diagnosed in 396 (4.9 percent) of the children. Multivitamin use at three and six months of age and at three years of age was associated with food allergies. Formula-fed infants who had been supplemented at three and six months had an increased risk of food allergy, as did breastfed children supplemented at three years.

Black children who receive early multivitamin supplementation may be at greater risk for asthma, and formula-fed children who receive vitamin supplementation may be at risk for food allergy. Breastfed infants are at risk for developing food allergies if they receive vitamin supplements later, at three years of age. The authors speculate that supplementation may produce the greatest risk for allergies in formula-fed children because formula already contains significantly higher doses of vitamins, especially vitamin D, than breast milk. However, the true reason for the associations found in this study is unclear. In addition, there is no proof that the association between multivitamin use and asthma and food allergies is causal. At this time, the American Academy of Pediatrics recommends vitamin D supplementation for all breastfed infants. Given the possibility of increased risk of developing allergies, this recommendation eventually may have to be revised.