Omega-3 and DHA for babies and toddlers: why it matters and where to get it

Feeding · Updated July 2026 · All articles

Among the nutrients that matter most for a baby's developing brain and eyes, omega-3 fatty acids, particularly DHA, sit near the top. The first two years of life are a window of rapid brain growth in which the right building blocks make a lasting difference. Understanding where omega-3 comes from, how to ensure your baby is getting enough, and what to do if your family does not eat fish gives you everything you need to make confident food choices.

What DHA and EPA are

Omega-3 fatty acids are a family of polyunsaturated fats with several members that play distinct roles in the body. The ones that matter most for infant development are:

• DHA (docosahexaenoic acid): the primary omega-3 fat in the brain and retina. The brain accumulates DHA rapidly in the third trimester of pregnancy and continues to do so throughout the first two years of life. DHA is a structural component of brain cell membranes and plays a role in neurotransmission, visual acuity, and cognitive development.
• EPA (eicosapentaenoic acid): works alongside DHA, with anti-inflammatory roles. Less concentrated in the brain than DHA but part of the overall omega-3 picture.
• ALA (alpha-linolenic acid): a short-chain omega-3 found in plant foods. The body can theoretically convert ALA to DHA and EPA, but this conversion is very inefficient, particularly in infants. ALA-rich foods such as flaxseed, walnuts, and chia seeds are not reliable DHA sources for babies.

Why DHA matters in the first two years

The brain more than doubles in size in the first two years of life, and this growth is partly a story of fat deposition. Approximately 60 percent of the brain's dry weight is fat, and DHA is one of the most abundant fats in brain tissue. During periods of rapid brain growth, adequate DHA supply is particularly important.

Studies examining DHA supplementation in pregnancy and early infancy have found associations between higher DHA intake and better visual acuity in infants, better cognitive outcomes in early childhood, and reduced rates of certain developmental problems. The evidence is strongest for the window from the third trimester through to 18 months. This does not mean that children who do not receive supplemental DHA are doomed to poor outcomes; most children develop normally. It does mean that ensuring adequate DHA from food sources during this period is a worthwhile priority.

Breast milk DHA: it reflects your diet

Breast milk contains DHA, but the amount varies considerably based on the mother's own dietary intake. Studies comparing DHA content in breast milk across populations have found that women who eat oily fish regularly have significantly higher breast milk DHA than women who eat little or no fish. In some populations where fish is a dietary staple, breast milk DHA is three to four times higher than in populations eating a Western diet with minimal fish.

If you are breastfeeding and eat oily fish two to three times a week, your breast milk DHA is likely adequate for your baby's needs. If you do not eat fish, whether for preference, allergy, or dietary choice, your breast milk DHA may be lower. An algae-based DHA supplement taken by the breastfeeding parent is the most reliable way to address this. The DHA from the supplement passes into breast milk and then to the baby.

Formula DHA

Since 2008, DHA has been required in all infant formula sold in the UK and EU. Any standard infant formula available today contains DHA. The amount added is regulated to ensure it meets infant needs during the formula-feeding period. If your baby is formula-fed, their DHA requirements during that stage are met by the formula without any additional supplementation needed.

Once weaning begins, the proportion of nutrition coming from formula decreases and solid foods become increasingly important for all nutrients including DHA. This is when regular inclusion of oily fish in the diet becomes relevant.

Oily fish from 6 months: the best food source

From 6 months, oily fish can be introduced as part of the weaning diet and is one of the most nutritionally dense first foods available. Oily fish provides DHA and EPA directly in their long-chain form, without conversion needed, along with high-quality protein, iron, zinc, iodine, selenium, and vitamin D.

Good oily fish choices for babies from 6 months:

• Salmon: mild flavour, easy to flake, readily accepted by most babies; tinned salmon is convenient and affordable
• Sardines: very high in omega-3; tinned sardines in spring water or olive oil work well mashed into food; remove any large bones
• Mackerel: strong flavour that some babies take to readily; very high omega-3 content; fresh, smoked, or tinned
• Trout: mild and well-tolerated; flakes easily; fresh or farmed
• Herring: excellent omega-3 source; less commonly offered but nutritionally valuable

Fresh tuna steaks are considered an oily fish, but canned tuna is not (the canning process reduces its omega-3 content). Canned tuna is still a useful protein and iron source but should not be counted toward the oily fish quota.

How much fish per week

The NHS recommends up to two portions of oily fish per week for babies and young children. A portion for a 6 to 12 month old is small, around 30 to 40 grams, roughly two to three tablespoons of flaked fish. Two portions per week across the weaning period provides ample DHA for brain development.

Girls should have no more than two portions of oily fish per week. This is because some oily fish contain low levels of persistent organic pollutants that, over a lifetime, could affect fertility. The concern is very long-term and population-level, not immediate, but the guideline applies as a precaution. Boys can have up to four portions per week.

Mercury: which fish to avoid

Certain large predatory fish accumulate methylmercury, a neurotoxin, through the food chain. These fish should not be offered to babies or young children:

• Shark
• Swordfish
• Marlin
• King mackerel (different from regular Atlantic or Pacific mackerel, which is fine)
• Tilefish

The oily fish recommended above, salmon, sardines, mackerel, trout, herring, do not present mercury concerns at the recommended serving frequency. These are the fish to offer babies and toddlers. The fish to avoid are, in practice, rarely on a family's regular menu anyway.

Algae-based DHA supplements: for non-fish eaters

For babies on plant-based or vegan diets, or for breastfeeding parents who do not eat fish, an algae-based DHA supplement is the appropriate solution. Algae is the origin of all marine DHA: fish accumulate DHA by eating algae (and smaller fish that ate algae). Algae-based DHA supplements skip the fish entirely and deliver the same DHA in a form suitable for infants.

Algae-based DHA supplements are appropriate from 6 months for babies who will not be eating fish. They are also appropriate for breastfeeding parents who do not eat fish, as supplementation increases breast milk DHA content.

Flaxseed oil and other ALA-rich plant oils are not adequate substitutes. The conversion of ALA to DHA is inefficient in adults and even more so in infants. Do not use flaxseed oil as an omega-3 supplement for a baby who does not eat fish.

No evidence for supplements when fish intake is adequate

For babies eating oily fish twice a week from 6 months, or for formula-fed babies, there is no evidence that additional DHA supplementation improves outcomes beyond what food provides. Supplements are most useful when the dietary source is absent. When two portions of oily fish are being eaten weekly, supplements are not necessary and spending money on them does not add measurable benefit.

Frequently asked questions

Does my breastfed baby get enough DHA?

The DHA content of breast milk reflects the mother's diet. Mothers who eat oily fish two to three times a week have significantly higher breast milk DHA than mothers who eat little or no fish. If you are breastfeeding and do not eat fish, an algae-based DHA supplement for yourself is the most reliable way to ensure your breast milk DHA content supports your baby's brain development.

Does infant formula contain DHA?

Yes. DHA has been added to infant formula as standard in the UK, EU, and many other regions since 2008. Any standard infant formula sold in the UK contains DHA. The source is typically algae-derived or from certain fish oils. If your baby is formula-fed, their DHA needs during the formula-feeding period are covered by the formula itself.

How much oily fish should a baby eat?

The NHS recommends up to two portions of oily fish per week for babies and young children from 6 months. A portion for a baby is a small amount, around 30 to 40 grams. Girls should have no more than two portions per week due to very long-term concerns about accumulated pollutants, while boys can have up to four portions. Oily fish includes salmon, mackerel, sardines, trout, and fresh tuna.

Which fish should I avoid giving my baby?

Shark, swordfish, and marlin contain high levels of methylmercury and should not be given to babies or young children. Canned tuna is lower in mercury than fresh tuna steaks and can be offered, but limit to no more than four cans per week for young children. King mackerel and tilefish are also high-mercury species to avoid. For most oily fish (salmon, sardines, mackerel, trout) there are no safety concerns at the recommended portions.

Is an omega-3 supplement necessary if my baby eats fish?

If your baby eats oily fish regularly from 6 months, two portions a week is sufficient to meet their DHA needs through food alone and no supplement is needed. An algae-based DHA supplement is most useful for babies on plant-based diets who do not eat fish, or for breastfeeding mothers who do not eat fish and want to ensure adequate breast milk DHA.

Is flaxseed oil a good omega-3 source for my baby?

Flaxseed oil and other ALA-containing plant oils are not adequate substitutes for DHA and EPA in infants. The body can theoretically convert ALA to DHA, but the conversion efficiency in infants is very low. For babies on plant-based diets, a direct algae-based DHA supplement is the appropriate choice rather than flaxseed oil.

This article is for general information only. If you have concerns about your baby's feeding or growth, speak to your health visitor, GP, or a registered dietitian.