Breastfeeding is still best for babies, although it may not protect against allergies.
Pregnant women and new mothers receive many messages regarding the benefits of exclusive breastfeeding for babies in the first year of life.
Allergy can be defined as "a hypersensitivity reaction mediated by immunological mechanisms," usually antibody-mediated.
The antibodies responsible for an allergic reaction usually belong to the IgE type, so that an individual may be said to be suffering from an IgE-mediated allergic disease, such as IgE-mediated asthma.
IgE is believed to have evolved as a defense mechanism against parasitic infestation, based on the fact that allergic responses typically affect the skin, gut, and respiratory tract, the major sites of parasitic invasion. IgE antibodies may play a beneficial "gate-keeper" role by recognizing foreign material early on or by enabling immune system response through improved antigen presentation.
For example, IgE allergic reactions trigger mucus secretion, sneezing, itching, coughing, bronchoconstriction, tear production, inflammation, vomiting and diarrhea, which are all mechanisms that expel allergenic proteins from the body.
Why would breast milk cause allergies?
Laleche League International argue that cow's milk and dairy products, on which formula is based, contain more than 20 substances that are human allergens. They say that feeding a baby artificial milk is equivalent to an adult drinking 7 quarts of milk a day. The high concentration of allergens thus triggers a rise in IgE levels, which sensitizes the baby, causing future allergies.
The American Academy of Asthma, Allergy and Immunology (AAAAI), among others, have also reported that breast milk is protective and "least likely to trigger an allergic reaction."
Researchers led by Dr. Quindelyn Cook, of the American College of Allergy, Asthma and Immunology (ACAAI), aimed to examine the association of breastfeeding and IgE sensitization to environmental allergens in patients with symptoms of rhinitis.
The team conducted a retrospective review of patient referrals to a pediatric allergy and immunology clinic at a large academic medical center between 2009-2013.
The study involved 194 eligible patients aged 4-18 years with a visit diagnosis of rhinitis and documented results of a skin prick test during the first two office visits. Infant feeding history was collected from new patient questionnaires.
The primary outcome measured was a positive skin prick to an environmental allergen. Secondary outcomes tested were asthma, atopic dermatitis and food allergy.
No difference in allergies between the two groups
Patients were divided into two groups based on whether they were ever breastfed or formula fed. There were 134 in the breastfed group, and 60 had been formula fed.
Both groups had similar numbers of patients with a positive skin prick test. They also had similar numbers of patients with asthma, atopic dermatitis and food allergy.
No significant difference in IgE sensitization was found between children who were ever breastfed versus formula fed.
Dr. Cook says:
Study author Dr. Christina Ciaccio, allergist and ACAAI fellow, urges new mothers to continue to breastfeed, because breastfeeding is known to be good for babies, and she calls for a larger, prospective study to verify the results and determine the applicability to the general population.
Medical News Today recently reported on research suggesting breastfeeding does not improve a child's intelligence.