Effects of diet supplements on allergies uncertain

By Joene Hendry

NEW YORK (Reuters Health) - A review of studies examining the usefulness of diet supplements - prebiotics and probiotics -- in preventing the development of allergic disease and food hypersensitivity in high-risk infants found insufficient evidence to support the routine use of these supplements. However, there was some evidence suggesting that prebiotics added to infant formula may lower the risk of eczema.

"Many infants become sensitized to foods, including infant formula, through their gastrointestinal tract, a process that may be affected by the composition of the intestinal bacteria," Dr. John Sinn told Reuters Health.

"Prebiotics (complex sugars that promote the growth of probiotic bacteria) and probiotics (bacteria with health-promoting properties) may prevent sensitization to foods," Sinn said.

To investigate the use of these supplements among infants, Sinn, of Royal North Shore Hospital, and co-author Dr. David Osborn, Royal Prince Alfred Hospital, both in Sidney, Australia, conducted two separate reviews that included 12 studies on the use of prebiotic and probiotic supplements in high-risk infants, who had no signs of allergy or hypersensitivity at the beginning of the study.

The findings suggested that the supplements may help prevent infant eczema, according to the report in The Cochrane Library, a journal of medical research,

"However," Sinn notes, "concerns regarding the quality of studies, inconsistency of findings between studies, and the fact that the benefits did not persist if restricted to infants with evidence of sensitization to food allergens, suggests that further studies are needed."

The probiotic analysis looked at the outcomes of 1549 infants supplemented for various durations over the first year of life. The prebiotic analysis included 442 infants treated for 6 months.

Sinn and Osborn again report evidence that probiotics may reduce the prevalence of clinical eczema, "but the evidence was not entirely consistent," Sinn said.

Moreover, the evidence was not sufficient enough to suggest routine probiotic supplementation for the prevention of eczema or any other allergic diseases among infants at high risk of allergies.

The investigators conclude that further research of both prebiotics and probiotics is needed before either can be recommended for routine use in infants at risk of allergies.

SOURCE: The Cochrane Library, October 2007.