In last week’s blog we explored when to introduce solids to your baby. It became clear that the new research is showing no benefit to delaying food introduction past 4-6 months and some decrease in allergy risk when food is introduced at 4-6 months. How do we make sense of this when previous research showed a benefit to waiting 12 months or more with certain food allergens? Let’s look at what is really going on and how we should introduce solids to baby.
First, let’s explore how our body deals with the introduction of something new. Our body’s immune system has many different responses to keep us healthy. First, there are the Th1 responses that fight infections and cancer. It is the Th2 responses that mount allergic responses or help to fight parasites. Then there are the Th3 responses that help the body recognize and tolerate non-harmful foreign substances or antigens. Whether they be airborne or ingested antigens, our body’s Th3 responses help dampen allergic reactions and promote an environment necessary for tolerance. Tolerance is an important piece of health because it helps decrease inappropriate allergic reactions as well as autoimmune reactions. It is exactly what we want when introducing food to baby.
When we look at the Th3 tolerance branch of the immune system, oral tolerance is something we should look at. Oral tolerance is the idea that introducing small amounts of the potentially allergenic food can help train the body to not react to the food. Many studies are beginning to show the potential for oral tolerance in the prevention and/or treatment of food allergies. For example, recent research demonstrated repeated administration of the allergen in slowly increasing doses, subcutaneously or sublingually, appears to be effective for allergic rhinitis. Tolerance is the principle behind injection immunotherapy or allergy shots. Recent reports have demonstrated partial success with oral, sublingual, subcutaneous and epidermal immunotherapy in the treatment of food allergies. [2,3,4,5] So now we know how important tolerance is to accepting food and not mounting a response to it. It is essential for baby’s transition to solids.
One of the major protective factors in introducing foods to baby is the presence of breast milk. Breast milk has so many immune boosting and stimulating components in it that are important for baby’s digestive, neurological and immune development and health. When combined with food introduction breast milk seems to help increase the tolerance of food antigens or potential allergens as recent research highlights. 1140 infants in the UK were followed to see if the timing of food introduction was connected with food allergies. Again, the study found that food introduced before 16 weeks increased the risk of allergy whereas introduction of solids after week 17 decreased risk of developing an allergic disease.  The study indicated that breast milk helps promote the tolerance immune response that we want during food introduction. Recent research also shows us that breastfeeding while introducing gluten reduces the risk of celiac disease by 52%.  It is easy to get caught up in the excitement and turn the exploration of solids into mini meal sessions as breastfeeding fades into the sunset. But it turns out that breastmilk is too important for overall health to let fade away. For the first year baby should be breastfed as the main source of nutrition as it helps promote tolerance, trains the immune system and promotes a healthy digestive tract in addition to all of the other health benefits.
To add another piece to the puzzle, an interesting study from April of this year showed the delay of solids increased the risk of the most common childhood cancer, Acute Lymphoblastic Leukemia.  Researchers suggested that the increased risk of cancer was a result of not exposing the immune system to food and leaving the immune system uneducated. The immature immune systems of infants need the education that food introduction brings. This study echoes some of the research that illustrates the importance of exposing baby to germs to let the immune system properly develop. It is important to have a balance. Our babies are born into this world and need to be introduced and fully enveloped by this world. They need contact with dirt and animals and food. Should we have baby snuggle up to the patients in the communicable disease ward with a peanut butter sandwich? Of course not, that would be ridiculous. As it turns out, it’s just as ridiculous to sanitize away most of the germs in our little ones’ world or make the transition to solids so black and white. We need a balance. Introducing foods to our babies should be gradual with plenty of rotation. Introducing a food and then having it become a daily fixture of baby’s diet is not the best method. They need to be exposed to a variety of foods and spices. But more on that next week when we explore what foods to introduce to baby in the third part of our series.
-Dr. Catherine Clinton
1- Petalas, K; Durham SR (2013). “Allergen immunotherapy for allergic rhinitis”. Rhinology 51 (2): 99–110.
2- A.D. Buchanan, T.D. Green, S.M. Jones, A.M. Scurlock, L. Christie, K.A. Althage, P.H. Steele, L. Pons, R.M. Helm, L.A. Lee, A.W. Burks Egg oral immunotherapy in nonanaphylactic children with egg allergy J. Allergy Clin. Immunol., 119 (2007), pp. 199–205
3- P. Meglio, E. Bartone, M. Plantamura, E. Arabito, P.G. Giampietro A protocol for oral desensitization in children with IgE-mediated cow’s milk allergy Allergy, 59 (2004), pp. 980–987
4- Fernandez-Rivas M, Garrido FS, Nadal JA, et al. Randomized double-blind, placebo-controlled trial of sublingual immunotherapy with a Pru p 3 quantified peach extract. Allergy. 2009;64(6):876–883
5- Dupont C, Kalach N, Soulaines P, Legoue-Morillon S, Piloquet H, Benhamou PH. Cow’s milk epicutaneous immunotherapy in children: a pilot trial of safety, acceptability, and impact on allergic reactivity. J Allergy Clin Immunol. 2010;125(5):1165–1167
7- Akobeng AK, Ramanan AV, Buchan I, Heller RF. Effect of breast feeding on risk of coeliac disease: a systematic review and meta-analysis of observational studies. Arch Dis Child. 2006;91(1):39–43