In 2001, the Word Health Organization recommended that babies be exclusively breastfed for 6 months, after which they should gradually be offered complementary foods until the majority of their diet consists of solid foods at around a year old. This replaced their earlier recommendation of exclusive breastfeeding for 4-6 months, after it was shown that babies nursed exclusively for the whole 6 months had fewer episodes of gastrointestinal disease, and their mothers benefited from greater weight loss postpartum and better birth control due to lactational amenorrhea. While also universally adopted by various national health organizations, some researchers maintain the evidence for this change was insufficient, doubting the capability of breastmilk to adequately nourish some infants until the age of 6 months in developed countries, where infectious disease is of relatively lesser concern (see here and here). These concerns are somewhat diminished by the recommendations to supplement all babies with vitamin D and iron, however.
However, it seems to be popular among the AP/NP set to delay the introduction of solid foods even past the six-month mark, some even past the first year. There seem to be multiple reasons for this:
* The idea that if breastmilk is the “perfect food” for babies, it will continue to be so even past 6 months. Solid food is described by some as an assault on the babies’ “virgin gut” – previously touched only by breastmilk.
We’ve discussed why this is fallacious here; in addition and in line with this thinking, AP/NP sites often encourage mothers not to supplement their breastfed babies with iron and vitamin D, despite the evidence that breastfed babies are prone to deficiencies of both compared to formula-fed ones.
Apparently, some ‘alternative’ sources (I’ve read of women referring to Mendelsohn’s book as a resource, for example, or taking the advice of their favorite ND) claim that all babies can subsist upon breastmilk alone for at least 12 months. Given that some breastfed babies are already demonstrating deficiencies in iron and zinc by 6 months, this makes little sense.
* The concept of ‘baby led weaning‘, which states that babies should not be fed until they are able to sit up and show interest in picking up finger foods and stuffing them in their own mouths. The idea, as far as I understand it, is that purees were necessary only in the days when babies were fed at very young ages and had spoonfuls of food thrust down their gullets, and when the baby’s motor coordination enables her to get her own food ensures that her chewing apparatus will also be sufficiently developed to handle regular table food.
Alas, it does not always seem to be the case that babies acquire motor skills and hand-eye coordination in exact accordance with their dietary needs. Also, many babies, even when starting solids older, seem to need the interim stage of pureed food before they acquire the skill of chewing. Not to mention that babies can easily bite off more than they can chew and choke in the process (my younger son was especially adept at that. Sometimes I wonder how he managed to make it through his first year and a half). And of course, for all the lip service paid to the process being “baby led”, if a baby clearly indicates he wants solid food by 4 or 5 months, even to the point of grabbing food, other rationales are used not to give him his ‘natural’ wish.
*The claim that delaying solids prevents sensitization to foods and consequently, allergies and autoimmune diseases. The original reasoning for this was the finding that babies until the age of 4-6 months have an ‘open’ or ‘leaky gut’ – meaning that the mucosal cell layer lining the intestinal tract of a young baby is permeable to protein-containing fluids. Over time, tight junctions appear between the intestinal cells, creating an impermeable barrier. The initial permeability of the intestine enables babies to receive various nutrients available in colostrum and early breastmilk; however, if allergenic proteins are introduced at this time, the thought was that these proteins could easily reach the baby’s blood stream and sensitize the immune system, causing future allergic reactions like eczema, asthma, celiac disease and various other specific manifestations of food allergy, and autoimmune diseases such as type 1 diabetes. The The American College of Asthma, Allergy, & Immunology still recommends very gradual and late introduction of potential allergens into babies’ diet, and complete avoidance of these allergens for years in babies who are at high risk for food allergies (even in utero).
However, newer research is coming to light that shows that delaying exposure to food allergens can be every bit as bad – i.e, there is an optimal window period during which it is best to introduce potential food allergens. This is a spinoff of the hygiene hypothesis, if you will – that a bit of early exposure may actually prevent sensitization to a given foodstuff.
In a recent study from Germany, delaying introduction to solid foods past 4 or 6 months wasn’t associated with fewer allergies at age 6. On the contrary, later introduction of solids was associated with more food allergies.
Regarding specific allergens, it seems that introducing cows’ milk products late (beyond 9 months) was associated with an increased incidence of eczema and recurrent wheezing, and delaying other foods beyond 7 months – also with allergies to inhaled substances at age 2. With regard to gluten (wheat protein), it seems that the optimal time for introduction of gluten-containing foods is between 3-7 months, both with regard to the development of celiac disease in susceptible infants and type 1 diabetes. Also important is that the babies were breastfeeding at the time the new foods were introduced.
Another study currently under way is examining early exposure to peanuts and the risk of developing peanut allergy later in life. This was prompted by the observation that children here in Israel, who eat a peanut-based snack called Bamba by the bagful as a weaning food (its consistency is airy and slightly softer than a large Rice Krispie, making it ideal for kids to hold and eat), have a significantly lower incidence of peanut allergies than their American and British Jewish counterparts. I don’t know if the association is causal and I resisted all attempts – and there were many! – to push Bamba on my own kids by well-meaning passersby until they were a year old, but we do seem to have a lot fewer peanut-allergic kids here (though such children do exist). The results of this study should be apparent by 2013.
In short, it may very well be that parents who delay introduction of solids beyond a certain point (7-9 months) may not be doing their babies any favors with regard to either acquiring the skills of eating, optimal nutrition or allergy/autoimmune disease prevention. In fact, it may be that introducing solids a bit earlier than the WHO currently recommends (at 4-6 months rather than 6, as was originally recommended) might be better.
As a result, the European Society for Pediatric Gastroenterology, Hepatology and Nutrition is now recommending that:
Exclusive or full breast-feeding for about 6 months is a desirable goal. Complementary feeding (ie, solid foods and liquids other than breast milk or infant formula and follow-on formula should not be introduced before 17 weeks and not later than 26 weeks. There is no convincing scientific evidence that avoidance or delayed introduction of potentially allergenic foods, such as fish and eggs, reduces allergies, either in infants considered at increased risk for the development of allergy or in those not considered to be at increased risk.
(If you click on no other link, please click on that position paper – it’s very comprehensive and deserves a read, IMO.)
DISCLAIMER: I recommend you always listen to your chosen pediatrician/allergist, especially if a child already has a food allergy, regardless of what I present here.