Pros and Cons of starting solids at 4 months vs 6 months

Pros and cons of starting solids at 4 months

Pros and Cons of starting solids at 4 months vs 6 months

Since 2002, the World Health Organization and Health Canada have recommended that babies start solid food around 6 months of life. Before 2002 we were encouraged to start our babies on complementary foods between 4-6 months. The change to six took a while to catch on with doctors and parents.

Most moms seemed to be were waiting until 6 months to introduce solid food, as recommended. Up until a year or two ago. It now 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 foods early, to prevent allergies. For all babies.

Is this true? What are the pros and cons of starting solids at 4 months vs 6? Read on to find out!

Can starting solids early prevent allergies?

The most recent Canadian recommendations on when to start allergenic foods are from the 2019 Canadian Pediatric 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, they continue to recommend introducing solids at about six months. This is when most babies show signs of readiness and require extra sources of nutrition to bump up iron stores.

The document defines ‘high risk’ as a baby that has a history of food allergies themselves or a parent/sibling with a food allergy. It’s still recommended to start common allergens at 6 months (but not before 4) for high-risk babies.

So where does this 4-month thing come from? In 2017 in 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 four to six 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 products 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). Compared to in the early 2000s, it was thought best to delay allergens until one to three 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 help prevent the allergy, rather than cause it. But somehow this recommendation to start allergens around six months has gotten warped to starting allergens for all babies at four months. This is not what is actually recommended, as you can see above.

Latest research on when to start solids: allergenic foods

Only one randomized controlled trial and expert opinion from 26 professional organizations supported the 2017 NIAID recommendation. What sole 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 2% of children who started peanuts early ended up with an allergy. 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:

The 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. At three months, half of the babies were 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 number of children with a food allergy at age 3 whether 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 did find 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.

But 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. Human milk is protective against allergies for the breastfed baby.

Maybe future evidence 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 that time.

Pros and cons of starting solids at 4 months

Pros of starting early

  • It may help with reflux, for babies suffering.
  • Research is not conclusive as to whether it will help prevent allergies in high risk babies.

Pros of waiting until 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 the World Health Organization, Health Canada, the 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 have developmental readiness and interest 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 to 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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