A Solid Start

Written by Clare Carrick ANutr BHSc (Nutrition and Health Promotion)

Scientifically reviewed by Dr Fathalla Ali, PHD Paediatrics


What, when, and how to introduce solids to your baby has to be one of the most confusing and divisive hurdles in that first year of your bub’s life…Your GP says one thing, your maternal child health nurse suggests another…The holistic naturopath you follow on instagram says definitely no rice cereal, but your mum says that rice cereal is the only way…Baby-led weaning, spoon-feeding, purees, finger foods, organic, iron-fortified, vegetarian, liver pate, bone broths…?!? It’s a minefield of decisions that, to be fair, would be hard to make even if you had had more than three hours sleep in the last month!! 

Considering these first couple of years are a crucial window for the development of your baby’s gut microbiome and immune system, and that diet plays a big role in this development, it’s understandable that parents get stressed out when starting solids. This article will break down some of the evidence for the best way to support your baby’s gut development, including one simple, but effective, gut-supporting concept…

But first, let’s look at the basics…

The Basics

Current guidelines in Australia recommend that you breastfeed exclusively, if possible, until around about 6 months of age, after which time you will start introducing solid foods alongside breastmilk or formula (1). Iron is one of the most important nutrients to consider at this point because breastmilk no longer contains enough of it, and this can come from iron-fortified cereal, meat and poultry purees, tofu and legumes (1). You can introduce foods in any order, as long as iron-rich foods are included and the texture is suitable for their age, so there’s no need to stress about whether you introduce, for example, lentils or pureed meat first (1). It is, however, recommended that you avoid nutrient-poor foods, like chips, cakes and biscuits, in this first year of life (1).

Solid Gut Evolution

On top of these basics, it has become increasingly evident that nurturing your baby’s gut microbiome should be a priority. Although there are numerous factors that influence babies’ gut microbiome, the biggest shift of all occurs when they start eating solid foods (2). What was, at birth, a fairly simple community of gut bugs with low diversity and richness, evolves rather quickly once solid foods are introduced, into a gut microbiome much more closely resembling that of an adult (2). 

The addition of vegetables, fruits, breads and cereals to your bub’s diet, which all provide different types of dietary fibres, help to feed the gut bugs (3). Certain strains of bacteria in particular, for example, those from the Lachnospiraceae, Ruminococcaceae, and Bacteroidaceae families, seem to thrive and prosper from the introduction of these foods (3). This also sparks the increase or appearance of some other important components, known as short chain fatty acids, and branched chain fatty acids, which, research has suggested, all help to support healthy growth and development, and possibly even protect against the development of allergies (3). 

The Greatest Influence Of All…

You probably want specific details on exactly what you feed your baby when introducing solids to nurture their gut. Considering how much mental space ‘introducing solids’ feels like it takes up for parents, this area remains surprisingly understudied, but there is one simple, gut-supporting concept that keeps popping up in the evidence…and it’s an idea that may help to change, and even relax, the way you think about introducing solids… It all comes down to the importance of diversity (2).

Diversity of Diet = Diversity of Gut 

Once upon a time, it was fairly common practice to wean your baby onto a diet consisting mainly of iron-fortified rice cereal…The focus was on getting enough iron (important!) and introducing more solid textures (also important!)…but dietary diversity was often ignored. 

We now know that our gut bugs love a diverse diet. This is because a diverse diet promotes a diverse microbiome, and a diverse microbiome creates more gut stability, which means a greater ability to fight infection or any detrimental effects of medication (2). 

Research has shown that babies who eat a large variety of foods, including all the top allergens, have a richer and more diverse gut microbiome than babies who eat the same couple of things every day (2). 

Biggest Takeaway

Today’s lesson… Try not to get too caught up in the polarising opinions you might come across when you’re introducing solids! It doesn’t have to be a definite ‘yes’ or ‘no’ to certain foods (e.g. rice cereals) or styles of eating (e.g. baby-led weaning vs spoon-fed) when it comes to gut health! Try to focus on diversity in their diet by letting your baby explore as many different foods as possible. Concentrating on the overall dietary pattern rather than individual foods may end up being the key to fostering a healthy, stable, and diverse gut microbiome that will help support your baby into a healthy future. 


  1. National Health and Medical Research Council. Infant Feeding Guidelines; National Health and Medical Research Council: Canberra, Australia, 2012. 
  2. Homann CM, Rossel CA, Dizzell S, Bervoets L, Simioni J, Li J, Gunn E, Surette MG, de Souza RJ, Mommers M, Hutton EK. Infants’ first solid foods: impact on gut microbiota development in two intercontinental cohorts. Nutrients. 2021 Jul 30;13(8):2639. 
  3. Laursen MF. Gut microbiota development: influence of diet from infancy to toddlerhood. Annals of Nutrition and Metabolism. 2021;77(3):21-34.
  4. Rinninella E, Cintoni M, Raoul P, Lopetuso LR, Scaldaferri F, Pulcini G, Miggiano GA, Gasbarrini A, Mele MC. Food components and dietary habits: keys for a healthy gut microbiota composition. Nutrients. 2019 Oct;11(10):2393. 

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