Choosing infant formula: what dietitians look for

By the DieticiansWorldwide.com editorial team · 17 October 2026 · Clinical nutrition

Start here: breastfeeding, formula and making a choice without guilt

The World Health Organization and UNICEF recommend that babies are fed only breast milk for the first six months of life, and that breastfeeding continues "up to 2 years of age or beyond" alongside solid food from six months (WHO, infant and young child feeding, 2026). Breast milk carries antibodies and other protective factors that formula cannot copy, and the NHS is clear that formula "cannot protect your baby from infections" in the way breastfeeding does.

Yet many families use formula. WHO's own figures show that only about 47% of infants aged under six months worldwide were exclusively breastfed between 2018 and 2025. Some parents cannot breastfeed, some combine breast and bottle, some have medical reasons, adopted babies, or returned to work. Whatever the reason, a baby who is formula-fed deserves a formula that is chosen well and prepared safely.

This guide follows the spirit of the WHO International Code of Marketing of Breast-milk Substitutes. It does not promote or compare named products. It explains what the categories mean, what the law already guarantees, which claims you can ignore, and when to bring in a health visitor, GP or paediatric dietitian. If you are still deciding whether to breastfeed, combine feed or move to formula, a midwife, health visitor or breastfeeding counsellor can support you before you buy anything.

What the law already guarantees about every formula

This is the most useful fact for anyone standing in front of a shelf of tins: the basic recipe is regulated, so the gap between cheap and expensive is far smaller than the packaging suggests.

• United States. The US Food and Drug Administration says its regulations "specify 30 nutrients that must be included in any infant formula sold in the United States", and it requires testing for the bacteria Salmonella and Cronobacter (FDA, infant formula). The FDA does not approve individual formulas, but manufacturers must notify it before marketing a new one.
• European Union. Regulation (EU) 2016/127 sets the composition and labelling of infant formula and follow-on formula. It made the addition of DHA, an omega-3 fat, mandatory in all infant formula from February 2020, and it states that "nutrition and health claims shall not be made on infant formula" (EUR-Lex, Regulation (EU) 2016/127).
• United Kingdom. In its February 2025 market study, the Competition and Markets Authority quoted NHS advice that "it does not matter which brand you choose, they'll all meet your baby's nutritional needs, regardless of price", and estimated that parents could save around £300 over a baby's first year by switching from a popular mid-priced product to a low-priced one (CMA, 2025).

So the starting assumption should be reassurance, not anxiety. A standard first infant formula bought from a reputable retailer, in date and undamaged, is nutritionally complete for a healthy term baby.

Infant formula types explained

Formula is usually made from cows' milk that has been treated to make it suitable for babies, and it comes as powder or as ready-to-feed liquid. The NHS lists the main types and when each is appropriate (NHS, types of formula). The table below summarises that guidance.

Standard first infant formula

For the large majority of babies, this is the whole decision. First infant formula is based mainly on whey, the protein thought to be easier to digest, and the NHS says your baby can stay on it after solids start at around six months and throughout the first year. Powder is cheaper; ready-to-feed liquid is convenient and is useful when you cannot make up feeds safely, for example when travelling, but it costs more and must be used sooner once opened.

Hydrolysed formula

"Hydrolysed" means the milk proteins have been broken into smaller pieces. The degree matters.

• Partially hydrolysed proteins are found in comfort formulas. They are not hypoallergenic and the NHS says they are not suitable for babies with cows' milk allergy.
• Extensively hydrolysed formula has proteins broken down far enough that most babies with cows' milk allergy can tolerate it. In the UK it is prescribed after a diagnosis. The American Academy of Pediatrics notes these formulas "tend to be costlier than regular formulas" and advises asking your paediatrician whether your baby needs one (AAP, HealthyChildren.org).
• Other specialist formulas exist for babies who do not tolerate an extensively hydrolysed formula or have more complex needs. They are chosen and prescribed by the medical team, never bought on spec.

Soya and goats' milk formula

Soya formula is often assumed to be the answer to milk allergy. It is not a first-line option. The NHS advises it only from six months and only under medical supervision, citing concerns about phytoestrogens and a higher risk of harm to teeth. The AAP adds that "soy formulas are not recommended in infants with cow milk allergy", because up to half of those infants also react to soya protein, and sees few situations where soya should be chosen over a cows' milk formula; galactosaemia, a rare inherited condition, is one.

Goats' milk formula is made to the same nutritional standards as cows' milk formula, but its proteins are so similar that it is not suitable for cows' milk allergy.

Formula for reflux: what to try, and in what order

Bringing up milk is one of the commonest reasons parents change formula. It is also one of the conditions that most often settles on its own. NICE guidance for England says effortless regurgitation affects at least 40% of infants, usually starts before eight weeks, and resolves in 90% of affected babies before their first birthday (NICE NG1).

When a formula-fed baby has frequent regurgitation with marked distress, NICE sets out a stepped approach:

1. Review the feeding history.
2. Reduce feed volumes, but only if they are excessive for the baby's weight.
3. Try smaller, more frequent feeds, while keeping the total daily amount of milk appropriate.
4. Then try a thickened formula, for example one containing rice starch, cornstarch, locust bean gum or carob bean gum.
5. If that does not help, stop the thickened formula and consider a 1 to 2 week trial of alginate, prescribed by a clinician.

Notice that changing the formula is step four, not step one. Anti-reflux formula may also need to be made up differently from standard formula, and the NHS warns that preparing it at lower temperatures "will not kill any harmful bacteria it may contain". Follow the instructions on the tin and the advice of the professional who suggested it.

Is expensive formula better?

The short answer is no, not nutritionally. Premium tins tend to advertise extra ingredients: added oligosaccharides, probiotics, nucleotides, "milk fat" blends or proteins described as closer to breast milk. When the European Food Safety Authority reviewed the essential composition of infant formula in July 2014, it concluded that "there is no need to add arachidonic acid, eicosapentaenoic acid, non-digestible oligosaccharides", and listed probiotics, synbiotics, chromium, fluoride, taurine and nucleotides among other substances that do not need to be added (EFSA, 2014). Manufacturers may still add optional ingredients, but those are not what makes a formula complete.

The CMA came to a matching conclusion from the other direction. Its recommendations included showing nutritional sufficiency information clearly in shops, online and on all packaging, banning unverifiable claims, and grouping brands together so parents can compare on price.

There are good reasons to pay more for a specific product, but they are medical, not marketing: a prescribed hydrolysed or amino acid formula, a specialist feed for a premature baby, or a thickened formula suggested by a clinician. If cost is causing stress, it is safe to move to a lower-priced standard first infant formula.

Which baby formula is closest to breast milk?

None of them, in the sense parents usually mean. Breast milk changes during a feed, across the day and as a baby grows, and it contains living cells and antibodies. No manufactured product reproduces that.

What formula does is supply the energy, protein, fat, carbohydrate, vitamins and minerals a baby needs, within legal limits based on scientific review. Phrases such as "inspired by breast milk" or "closest yet" describe marketing positions, not a measurable standard. That is one reason EU law prohibits nutrition and health claims on infant formula. A useful rule for dietitians and parents alike is to judge a formula by its type (first infant, extensively hydrolysed, and so on) and by safe preparation, not by adjectives on the tin.

How to read an infant formula label

Use the label to confirm you have the right product, not to rank brands.

• The stage and age. Make sure it says first infant formula, suitable from birth. The NHS warns that follow-on formula labels "can look very similar", and follow-on formula should never be given to a baby under six months.
• The protein source. Cows' milk, goats' milk, soya, partially hydrolysed or extensively hydrolysed. Only prescribed hypoallergenic formulas, such as extensively hydrolysed formula, are designed for cows' milk allergy.
• Iron. The AAP recommends iron-fortified formula for all infants who are not breastfed and says the iron in formula does not cause constipation or upset stomach. Low-iron formulas should not be used. Our article on B12 deficiency covers another nutrient that matters in infancy, particularly for babies of mothers on a vegan diet.
• Preparation instructions and scoop. Every product has its own scoop and water-to-powder ratio. Never use the scoop from a different tin.
• Dates and packaging. Do not buy damaged, swollen or unsealed containers, and check the use-by date.
• Where it came from. The FDA advises caution with imported formula bought online or from third-party sellers, which may not meet US safety or nutrition standards.

Safe preparation: how strict does it need to be?

Very strict. This is the part of formula feeding where the rules are not a matter of preference. Powdered formula is not sterile, and bacteria multiply quickly in warm milk. The NHS method (NHS, how to make up baby formula) is designed around one principle: water at 70°C or above kills harmful bacteria.

1. Boil at least 1 litre of fresh tap water. Do not use water that has already been boiled.
2. Leave it to cool for no more than 30 minutes, so it stays at 70°C or above.
3. Clean the work surface and wash your hands. Use bottles, teats and equipment that have been sterilised.
4. Pour the exact amount of water into the bottle first, then add the powder using the scoop supplied, loosely filled and levelled with a clean, dry knife.
5. Fit the teat and cap and shake until the powder dissolves.
6. Cool the bottle under cold running water and test the temperature on the inside of your wrist. It should feel warm or cool, not hot.
7. Throw away any formula left after a feed. Make feeds up one at a time, as needed.

The NHS also says not to add extra powder or extra water, not to add sugar or cereal, and not to warm bottles in a microwave because it heats unevenly. If you use a preparation machine, the water must reach at least 70°C; a digital food thermometer will tell you. Bottled water is generally not recommended unless tap water is unsafe.

Two further warnings come from the FDA. Never dilute formula to make it last longer, because watered-down formula lacks nutrients. And do not make formula at home: in February 2021 the FDA "strongly" advised parents not to make and feed homemade infant formula after reports of infants hospitalised with low calcium (FDA, 2021). If you are struggling to buy formula, speak to a health visitor, GP, food bank or local family service rather than stretching or improvising feeds.

When should a baby switch formula?

Less often than the market suggests. The NHS states that "there's no evidence that switching to a different formula does any good or harm", and that first infant formula is the only formula most babies need in their first year. The common prompts to switch, and what usually happens instead, are these:

• Crying and wind. Many babies cry a lot in the first months whatever they are fed. Comfort and hungrier-baby formulas have no evidence of benefit, so check feeding technique, teat flow and feed volumes first.
• Reflux. Follow the NICE steps above before moving to a thickened formula.
• Suspected cows' milk allergy. Signs such as eczema, vomiting, diarrhoea, blood in stools or hives after feeds need a GP assessment. If allergy is diagnosed, the switch is to a prescribed extensively hydrolysed formula, not to goats', soya or lactose-free formula.
• Turning six months. No change is needed. Follow-on formula offers no benefit.
• Turning one. Most children can move to whole or semi-skimmed cows' milk as a main drink. The NHS says children aged one to five do not need growing-up or toddler milks.

If you do change brands within the same type, there is no need for an elaborate transition. Simply follow the new product's preparation instructions exactly.

Generic feeding charts or an individual plan from a dietitian?

Tins print feeding tables by age and weight, and they are a reasonable guide for healthy babies who are growing well. But they are averages. A baby's appetite varies from day to day, and responsive feeding, watching for hunger and fullness cues rather than finishing every bottle, matters as much as the volume on the chart.

An individual plan from a paediatric dietitian is worth having when:

• your baby has a diagnosed or suspected cows' milk allergy, or more than one food allergy;
• your baby was born prematurely, has a heart, kidney or gut condition, or needs a specialist feed;
• weight gain is slow or growth has crossed down the centile lines;
• feeds are a daily struggle, with refusal, gagging or distress. Persistent fussy eating that continues into toddlerhood can occasionally signal ARFID, which needs specialist support;
• you are combining breast and formula feeding and want to protect your milk supply.

Our guide to the paediatric dietitian explains what these specialists do and how referrals usually work. In the UK, "dietitian" is a protected title, and the United Kingdom country guide shows how registration is checked; elsewhere, our explainer on the difference between a dietitian and a nutritionist shows what to look for.

Feeding a baby also sits within the whole family's eating. If you had gestational diabetes in pregnancy, for example, your own follow-up care and eating pattern after the birth matter too, and our free healthy eating check is a quick way to review your own diet while you focus on your baby's.

Book a session with a dietitian

A dietitian's checklist for choosing infant formula

1. If you can and wish to, get breastfeeding support first; combination feeding is also an option.
2. For a healthy term baby, choose any standard first infant formula. Price and brand do not change its nutritional adequacy.
3. Do not choose specialist formulas, including comfort, hungrier-baby, lactose-free, anti-reflux, soya or hydrolysed, without advice from a health professional.
4. Prepare every feed with water at 70°C or above, the scoop supplied, and the exact ratio on the label.
5. Never dilute formula, add cereal, or make formula at home.
6. Stay on first infant formula for the first year; skip follow-on and growing-up milks.
7. If your baby is unwell, not gaining weight or reacting to feeds, see your GP or health visitor before changing products.