No Evidence That Avoiding Foods While Breastfeeding Prevents Allergies

Women whose infants have known milk protein allergies or whose families have known allergies are properly told to avoid drinking milk themselves while breastfeeding. Milk proteins from the food can travel through the bloodstream and enter the breast milk, triggering allergic responses in the infants.

This advice has been widely disseminated in recent years. Perhaps too widely. The American Academy of Pediatrics (AAP) is afraid that women whose infants have no such allergies may be denying themselves foods out of fear of triggering allergies, even when those are unlikely.

In fact, the AAP feels this is such a problem that it has issued updated guidelines that reassure nursing mothers that no good evidence exists that avoiding certain trigger foods will prevent allergies from occurring.

Carla Johnson of the Associated Press reported the new policy in a story that I'm glad to see was widely covered. (The link goes to the Houston Chronicle, which reprints more of the article than some other newspapers.)

In August 2000, the doctors group advised mothers of infants with a family history of allergies to avoid cow's milk, eggs, fish, peanuts and tree nuts while breast-feeding.

That advice, along with a recommended schedule for introducing certain risky foods, left some moms and dads blaming themselves if their children went on to develop allergies.

"They say, 'I shouldn't have had milk in my coffee,'" said Dr. Scott Sicherer of the Mount Sinai School of Medicine's Jaffe Food Allergy Institute in New York. "I've been saying, 'We don't really have evidence that it causes a problem. Don't be on a guilt trip about it.'"

Mothers of high risk infants should still breast feed exclusively for at least the first four months, though.

The study is in the journal Pediatrics. You can read the full text online at Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Timing of Introduction of Complementary Foods, and Hydrolyzed Formulas by Frank R. Greer, MD, Scott H. Sicherer, MD, A. Wesley Burks, MD and the Committee on Nutrition and Section on Allergy and Immunology. PEDIATRICS Vol. 121 No. 1 January 2008, pp. 183-191 (doi:10.1542/peds.2007-3022)

Here's the Summary:

It is evident that inadequate study design and/or a paucity of data currently limit the ability to draw firm conclusions about certain aspects of atopy prevention through dietary interventions. In some circumstances in which there are insufficient studies (pregnancy and lactation avoidance diets, timing of introduction of specific complementary foods), the lack of proven efficacy does not indicate that the approach is disproved. Rather, more studies would be needed to clarify whether there is a positive or negative effect on atopy outcomes. The following statements summarize the current evidence within the context of these limitations.

1. At the present time, there is lack of evidence that maternal dietary restrictions during pregnancy play a significant role in the prevention of atopic disease in infants. Similarly, antigen avoidance during lactation does not prevent atopic disease, with the possible exception of atopic eczema, although more data are needed to substantiate this conclusion.

2. For infants at high risk of developing atopic disease, there is evidence that exclusive breastfeeding for at least 4 months compared with feeding intact cow milk protein formula decreases the cumulative incidence of atopic dermatitis and cow milk allergy in the first 2 years of life.

3. There is evidence that exclusive breastfeeding for at least 3 months protects against wheezing in early life. However, in infants at risk of developing atopic disease, the current evidence that exclusive breastfeeding protects against allergic asthma occurring beyond 6 years of age is not convincing.

4. In studies of infants at high risk of developing atopic disease who are not breastfed exclusively for 4 to 6 months or are formula fed, there is modest evidence that atopic dermatitis may be delayed or prevented by the use of extensively or partially hydrolyzed formulas, compared with cow milk formula, in early childhood. Comparative studies of the various hydrolyzed formulas have also indicated that not all formulas have the same protective benefit. Extensively hydrolyzed formulas may be more effective than partially hydrolyzed in the prevention of atopic disease. In addition, more research is needed to determine whether these benefits extend into late childhood and adolescence. The higher cost of the hydrolyzed formulas must be considered in any decision-making process for their use. To date, the use of amino acid–based formulas for atopy prevention has not been studied.

5. There is no convincing evidence for the use of soy-based infant formula for the purpose of allergy prevention.

6. Although solid foods should not be introduced before 4 to 6 months of age, there is no current convincing evidence that delaying their introduction beyond this period has a significant protective effect on the development of atopic disease regardless of whether infants are fed cow milk protein formula or human milk. This includes delaying the introduction of foods that are considered to be highly allergic, such as fish, eggs, and foods containing peanut protein.

7. For infants after 4 to 6 months of age, there are insufficient data to support a protective effect of any dietary intervention for the development of atopic disease.

8. Additional studies are needed to document the long-term effect of dietary interventions in infancy to prevent atopic disease, especially in children older than 4 years and in adults.

9. This document describes means to prevent or delay atopic diseases through dietary changes. For a child who has developed an atopic disease that may be precipitated or exacerbated by ingested proteins (via human milk, infant formula, or specific complementary foods), treatment may require specific identification and restriction of causal food proteins. This topic was not reviewed in this document.