“The quality of children’s diets is more important before age 2 than at any other time in life.” UNICEF 2020
A quick recap on the first 1,000 days (recap)
From conception through to your child’s second birthday (aka the first 1,000 days), nutrition plays a powerful role in shaping their lifelong health, development, and well-being. This critical window is marked by rapid growth, accelerated brain development, and evolving immune function, making what (and how) your little one eats during this time especially important. Good nutrition in these early years lays the foundations for everything from brain development to disease risk in adulthood.
Why early nutrition matters
Compared to adults, infants need a lot more energy and nutrients per kilogram of body weight. That means their diets need to work harder to support:
● Healthy physical growth
● Brain development (especially movement, language, and emotional regulation skills)
● A robust and well-trained immune system
It’s also a time when the developing gut microbiome is highly adaptable. The trillions of microbes that live in their gut are still developing, making it easier to shape a healthy microbial community before it stabilises around 3 years of age.
Breastfeeding: more than just food
If breastfeeding is an option for you, it can be an incredible way to support a child’s healthy start. The World Health Organisation (WHO) and UNICEF recommend initiating breastfeeding within one hour of birth, continuing exclusively for the first six months and then alongside solid foods where possible.
Why? Because breast milk is more than just food. It’s a living fluid rich in enzymes, antibodies, hormones, and beneficial bacteria.
Colostrum, the first milk, is often described as the baby’s "first vaccine" thanks to its high levels of immune-supporting compounds. Mature breast milk then provides all the nutrients (with the exception of vitamin D*) that an infant needs for the first 6 months of life (9).
Breastfeeding is linked to:
● Lower risk of infections (like colds and tummy bugs)
● Lower rates of sudden infant death syndrome (SIDS)
● Healthier weight gain patterns
● Reduced risk of allergies and autoimmune diseases later in life
It can be beneficial for breastfeeding mothers, too, as it helps:
● Reduces the risk of breast and ovarian cancers
● Supports postnatal weight management
● Lower the risk of type 2 diabetes (in women without gestational diabetes)
● Saves money on formula and is extremely convenient
*The NHS recommends all infants from birth to 1 year should have a daily supplement containing 8.5 to 10 micrograms of vitamin D throughout the year if they are breastfed (or formula fed with less than 500ml per day). A ten micrograms Vitamin D daily supplement is also recommended for children 1-4 years old, as well as for breastfeeding mums all year round, and other mums during the winter months (e.g. from the start of October to the end March).
Your baby’s microbiome: laying the groundwork
The gut microbiome starts establishing itself early and is shaped by factors like birth method (whether it’s a vaginal or caesarean birth) and feeding, influencing the development of baby’s immune system. Breast milk is a powerful driver of this process — not just for its nutrients, but for the beneficial microbes and compounds it delivers.
Breast milk contains a rich mix of bacteria, including those from the Staphylococcus, Streptococcus, Bifidobacterium, and Lactobacillus genus.
These microbes support:
● Education of immune cells and development of the immune system
● Gut barrier function
● Protection against harmful bacteria
Just as important are human milk oligosaccharides (HMOs) - these are special carbohydrates that feed helpful gut bacteria like Bifidobacterium and therefore help shape the developing microbiome.
What if breastfeeding isn’t an option?
If breastfeeding isn’t an option, infant formula can play a vital role in supporting your baby’s gut microbiome development. Many modern formulas are carefully and thoughtfully designed to include ingredients like probiotics and prebiotics (e.g. HMOs) that help nourish beneficial bacteria in baby’s digestive tract. These components mimic some of the protective qualities found in breast milk and can promote a balanced microbiome. With ongoing innovations in nutritional science, infant formulas are becoming increasingly sophisticated in helping babies thrive, if breast milk isn't possible.
While feeding plays a huge role, it’s not the only factor to consider. Exposure to nature, pets and varied outdoor environments helps to promote microbial diversity too. By the age of two, a child’s gut microbiome begins to resemble that of an adult, so these first few years are key for setting the tone.
Colic and the gut:
We still don’t fully understand what causes colic, but emerging research suggests that the gut microbiome may play a role. Difficulty digesting milk, an underdeveloped or immature gastrointestinal tract, or even a disrupted gut microbiome - which can happen for reasons outside of your control, such as birth circumstances and certain medications (like antibiotics) - could all be contributing factors.
Studies show that babies with colic often have lower bacterial diversity in their gut, increased levels of gas-producing bacteria, and fewer anti-inflammatory bacteria like Bifidobacterium and Lactobacillus.
If your baby is crying intensely without a clear reason and you suspect Colic - read our blog on Colic – top tips for you and your baby, and consider giving your baby live bacteria Bifidobacterium lactis BB-12® (dose 1 Billion per day).
Complementary feeding: beyond breast milk or formula
At around six months (and not before 4 months), babies need more than milk alone. This is when complementary feeding begins: introducing solid, semi-solid, and soft foods alongside breastfeeding or formula - also known as weaning.
Some guiding principles:
● Wait until around 6 months to start solids – always consult with your healthcare professional if you’re thinking of starting weaning before 6 months - for example if your baby has severe eczema and you would like to discuss introducing egg and peanut early to reduce the risk of developing a food allergy.
● Responsive feeding: tune into your baby’s hunger and fullness cues
● Offer variety early and often, especially with fruits and vegetables
● Focus on nutrient-dense foods as babies only eat small amounts
More information on weaning your baby can be found here
A good guideline is the Minimum Dietary Diversity - provide foods from at least five of these eight groups daily:
- Breastmilk
- Grains, roots, and tubers
- Pulses
- Dairy - Whole cow’s milk can be used in cooking from 6 months, but shouldn’t be given as a main drink until 12 months, due to the risk of low iron intake.
- Flesh foods (like chicken, fish etc)
- Eggs
- Fruits and vegetables
From 6 months, babies need iron-rich foods (meat, fish, eggs, pulses, fortified cereals) because stores from birth begin to run low. This is especially important if the baby was premature or had a low birth weight.
Introducing potential allergens like peanuts and eggs from 6 months is also recommended to help prevent future food allergies. That is, unless there is a family history of food allergy, in which case it’s important to consult your healthcare professional before introducing common allergenic foods.
What to avoid in early infancy
According to UK guidelines it’s important for your baby to avoid the following foods where possible:
● Added salt or sugar
● Sugar-sweetened beverages, including juice - to protect dental health and reduce the risk of obesity later in life
● Rice drinks (due to arsenic risk) - please discuss dairy alternatives with a health care professional and choose those designed for children or those fortified with calcium and iodine at the least.
● Low-nutrient, high calorie snacks - such as chocolate, sweets (choking hazard) biscuits and crisps
● Bottles after 12 months (switch to a cup) - to help with oro-motor development
These recommendations aim to support healthy eating habits, now and in the future.
Optimal nutrition for future health
Poor early nutrition can lead to stunted growth, weakened immunity, impaired learning, and increased risk of chronic disease later in life. Meanwhile, good nutrition in the first 1,000 days can help support:
● Healthy growth and development
● Strong immune and digestive systems
● Reduced childhood illness and hospitalisations
● Better school performance and future productivity
● Reduce future risk of developing chronic disease in later life
In Summary
The first 1,000 days are a once-in-a-lifetime opportunity to nourish your child for their development and future. Whether you’re breastfeeding, formula feeding or both, what you feed, how you feed, and the environment you create all play a role. It’s never about perfection, just progress, variety and compassion, for you and your baby. Small, consistent positive choices matter most, and feeding challenges are common and normal - reach out to a health care professional for tailored advice if you need it.
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Written by Rachel Redman - Registered Dietitian
Reviewed by Nichola Ludlam-Raine: Specialist Registered Dietitian
