When, How and What? What science actually says about starting your baby on solids

It's less confusing than you'd think

For most aspects of parenting, there is a general consensus about how to do things. Sure, when it comes to where baby sleeps there are differences of opinion, but everyone agrees on roughly how much sleep a baby needs. Some people breastfeed, others bottle feed, and some mix and match, but everyone knows that babies need milk and roughly agree on how much. Your doctor and your grandma and your best friend all offer advice that is generally consistent.

But when it comes to starting baby on solids, there is no agreement.

Your doctor says wait until 6 months. Your grandma is worried that they’re hungry for solids by 3 months. Your friend says wait for signs of readiness. One doctor says start with vegetables, while another says start with baby rice cereal. Your grandma is pushing purees, while your friend insists that baby led weaning is the way to go. No one seems able to agree, and you’re beginning to wonder if it even matters.

Obviously the baby is looking confused about if they should be eating from a spoon, if they are eating the ‘right’ food, or for that matter, if they’re even old enough to be eating at all! Photo by hui sang on Unsplash

The thing is, in no other area of parenting have there been such drastic changes in cultural norms over the last century. And not only has common practice shifted, but official guidelines seem to be constantly updating too. In addition, different countries seem to have different rules about not only what food to start your baby on, but what age too, and they’re not all in line with the WHO recommendations. It’s literally impossible for a first-time parent to make an informed decision without reading dozens of research papers, doctoral dissertations, and working papers from governmental agencies. Good news is that I’ve read all that for you!

So, what does the science say about how to start your baby on solids?

Well, before we can answer that question, we need to have the end in sight. If we don’t know the goal of starting solids, as the Cheshire cat said to Alice, “Then it doesn’t much matter which way you go.”

Why?

Why do we start children on solids?

Interestingly, the reasons we start babies on solids today are vastly different to those that shaped the decision to introduce solids throughout most of human history and, indeed, across the entire world of mammals. Breastmilk is nutritionally complete for young infants, meets the energy requirements for a young baby, and boosts immunity through antibodies. All good things for babies. HOWEVER producing breastmilk is energetically demanding on the mother and limits her biological fitness by preventing her from falling pregnant again. Therefore, there is a trade-off between what is good for the baby and what is good for the mother. For most of human history, the goal was to start on solids early enough for the mother to reproduce again quickly, but not so early that the baby would experience undernutrition or exposure to pathogens and die.

Nowadays, most mothers aren’t aiming to produce lots of kids. We aren’t worried (at least in Australia and other affluent countries) about undernutrition. And the risk of exposure to pathogens is greatly reduced.

Additionally, our food culture is very different. Up until very recently, there was no such thing as calorically dense, highly processed foods. There was less added sugar and added salt. Most foods were whole foods or minimally processed like butter and flour. Back then, the biological preference infants have for sweet food simply predisposed them to prefer breastmilk and fruit. Today, this biological preference predisposes them to obesity. Over-nutrition is a greater risk in affluent countries today, with some 66% of Australian adults and 26% of Australian children experiencing being over-weight or obese.

This means that simply looking back at what our hunter-gatherer ancestors did and trying to apply it to today isn’t going to work. Our environment is too different.

So why do we start our babies on solids now?

There are dozens of potential reasons. To hit that next milestone (interestingly, a big factor that led to the very early introduction to solids in the mid-1900s was that no one wanted to be the last to hit this milestone). To make it simpler for others to feed the baby (this is true, particularly if you’ve been exclusively breastfeeding, but there are other ways for secondary caregivers to bond with the baby). To help your baby sleep better (yet babies tend to increase both breastfeeding and wakefulness around this time, irrespective of if they’ve started on solids). Because everyone else is doing it (“if everyone else jumped off a cliff, would you do it too?” as my mum would say).

But here’s what I think the underlying reason should be: To maximise our child’s long-term health outcomes. And that is the lens I used when evaluating the research about when, how, and what to feed your baby when starting on solids.