Benefits of starting solids at 6 months vs 4 months

When is the best time to start my baby on solid food: 4 months vs 6 months?

Benefits of starting solids at 6 months vs 4 months

Since 2002, the World Health Organization and Health Canada have recommended that babies start solids around 6 months. Before 2002 the recommendation used to be to start solids between 4 to 6 months. The change to 6 months took a while to catch on with doctors and parents. 

Most moms seem to be were waiting until 6 months to introduce their baby to solids, as recommended. Up until a year or so ago. But now that seems to be changing again!

Lately, I’ve been noticing a trend of starting solids earlier again. Like between 3-5 months. Usually, the mom will reference “new research about introducing allergens.” Or their doctor recommended starting solids early, to prevent allergies. For all babies.

Is this true? Is starting solids before the recommended age of 6 months beneficial for your baby to prevent allergies? Or do the benefits of starting solids at 6 months outweigh this?

Can starting solids before 6 months prevent allergies?

The most recent Canadian recommendations on when to start allergenic foods are from the 2019 Canadian Paediatric Society. They published a document titled “Timing of introduction of allergenic solids for infants at high risk”.

For babies at low or no risk of food allergy, the Candian Paediatric Society continues to recommend introducing solids at about 6 months.

The document defines ‘high risk’ as a baby that has a known allergy or a parent/sibling with food allergy. For high-risk babies, it’s still recommended to start allergic foods around 6 months (but not before 4 months).

So where does this 4-month thing come from?

In 2017 the United States, the National Institute of Allergy and Infectious Disease (NIAID) published a document called: Addendum Guidelines for the Prevention of Peanut Allergy in the United States.

Specifically, in relation to peanut allergy, the guidelines suggest:

For infants with eczema, egg allergy or both: Consider testing for peanut allergy before introducing peanuts into the baby’s diet. Based on test results, the earliest age of peanut introduction is 4-6 months.

For infants with mild to moderate eczema: the earliest age of peanut introduction is recommended as “around 6 months.”

For infants with no eczema or any food allergy: the earliest age of peanut introduction is: “Age-appropriate and in accordance with family preferences and cultural practices.” 

The Candian Society for Clinical allergy and Clinical Immunology also endorsed the guidelines, summarized as: “The “take-home” messages include that peanut should be introduced early in the first year of life, and for the majority of infants, peanut can be introduced at home.”

So the newest recommendations encourage parents not to delay introducing peanuts and other high-risk allergens (eggs, wheat, dairy, tree nuts, soy). This is a change from the early 2000’s when it was thought best to delay allergens until 1-3 years. And it’s working! Peanut allergy prevalence in 2018-19 was 2.6% compared to 3.1% in 2007-11: a 16% decrease.

So now we know that introducing high-risk allergens can promote tolerance to the allergy, rather than cause it. But somehow this recommendation to start allergens around 6 months has gotten warped to starting allergens for all babies at 4 months. Which is not what is actually recommended, as you can see above,.

Latest research on when to start solids: allergenic foods

One randomized controlled trial and expert opinion from 26 professional organizations supported the 2017 NIAID recommendation. What single-trial informed the NSAID recommendations to potentially start peanuts at 4 months? 

The LEAP “Learning Early About Peanut Allergy” (LEAP) study. 

The study included 640 babies, half of who started eating peanuts early and regularly (starting between 4 to 11 months). The other half tried peanut protein for the first time late (5 years). All participants were at higher risk for allergies, defined in this study as having a known egg allergy, severe eczema or both. 

The study found that the prevalence of peanut allergy in the children who started peanuts early was 2%. The group that avoided peanuts until late had higher rates of peanut allergy: 14%.

One important thing to note is that the average age of starting the LEAP trial in the early introduction group was 7.8 months. Not 4 months.

But there has been some other research looking at whether introduction before 6 months might be beneficial.

The EAT (Enquiring about tolerance) study:

Authors of this study hypothesized that starting solids before 3-4 months may actually increase allergy risk. Possibly because the bacterial colonization hasn’t been completed to improve immunity or gut is too ”leaky.”

To test this, the researchers included breastfed infants from the United Kingdom. Half of the babies were supposed to be introduced to peanuts, cooked eggs, cow’s milk, sesame, whitefish, and wheat at about 3 months of age. The other half was to start these allergenic proteins as normally recommended, at 6 months. 

They found there was no significant difference in the proportion of children with a food allergy at age 3 when they started these highly allergenic foods at either 3 or 6 months.

But these results could be inaccurate because many of the early-introduction group didn’t successfully follow the study design. When looking at the smaller group of participants that were actually able to introduce the 6 allergens at 3 months, they found a lower risk of food allergy for the early introduction group compared to the 6-month introduction group (2.4% vs. 7.3%). This was for egg and peanut only, not the other allergens.

Only 31.9% of all the babies in the early-introduction group were successful at starting the allergens early. Compared to over 80% in the standard introduction group. My own interpretation of this is that it’s difficult to feed a 3-month-old, as they’re not developmentally ready for solids yet!

My final opinion? Is it better to start solids early to prevent allergies?

So there may be a small benefit in terms of allergy prevention to start solids “early.” I think it’s too early to say.

But even so, it might not be practical for most babies. Especially if you want to do baby-led weaning or self-feeding. Under 6 months most babies will not be developmentally ready.

Another point to consider is that the current recommendations from the World Health Organization (and all government health organizations in developed nations) support exclusive breastfeeding up to 6 months of age. Exclusive breastfeeding is also protective against allergies.

Maybe future research will more strongly support the introduction of allergens before 6 months in high-risk infants. For now, if you have a high-risk baby, discuss with your allergist whether early introduction of solids may be beneficial.

 But for all babies (including those at high risk for an allergy), introducing peanuts at 6 months of age fits within the current guidelines recommending starting solids and allergens at 6 months.

Benefits of starting solids at 6 months

  • It’s easier. Sure starting solids is an exciting new step – but also extra work and clean up!
  • It’s still the official recommendation from Health Canada, Canadian Paediatric Society and Dietitians of Canada.
  • It allows your baby full benefits of breast milk – protection from immunoglobulins and gut bacteria.
  • Your baby will be more developmentally ready and interested in solids.
  • Starting solids before 4 months may actually increase risk of allergies and has not conclusively been shown to decrease allergies (yet, anyway).

Want more info about how to start solids using Baby-led Weaning? Click here register for my free webinar “How to get started using Baby-led Weaning”

 Jennifer House is a Registered Dietitian, author & mom of 3. From Baby-led weaning to picky eating and meal planning, she helps you to make feeding your family easier.

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