Why omega-3 is important for children's brains and development
TL;DR
The omega-3 fatty acids DHA and EPA — primarily from fatty fish — are crucial for the development of the brain and eyes in children. The Danish Health Authority recommends fish twice a week. Children who do not eat fish may consider algae-based DHA supplements instead of fish oil.
Omega-3 for children is not just a health trend. The brain's gray matter consists of about 60% fat — and DHA (docosahexaenoic acid) is the most important single building block. The first 1000 days of a child's life are the period when the brain grows fastest, and DHA availability during this period has measurable effects on cognitive function, language acquisition, and visual sharpness. This is not abstract nutritional science — it is documented in many long-term studies. And the good news: two servings of fatty fish per week are enough.
What is omega-3 — ALA, EPA, and DHA explained
There are three types of omega-3 fatty acids. DHA and EPA from fish are the biologically active ones. ALA from plants can be converted to DHA and EPA, but the conversion is limited — only 5-10% is converted.
Omega-3 fatty acids are a family of polyunsaturated fatty acids:
- ALA (alpha-linolenic acid) — plant-based. Found in flaxseeds, chia seeds, and walnuts. Essential fatty acid the body cannot produce itself.
- EPA (eicosapentaenoic acid) — primarily from fish. Anti-inflammatory effect, important for the immune system.
- DHA (docosahexaenoic acid) — primarily from fish and algae. Makes up about 40% of brain tissue and 60% of the retina in the eye.
The body can theoretically convert ALA to DHA and EPA, but the efficiency is low. A review in Nutrients shows a conversion rate of only 5-10% for EPA and under 4% for DHA. This is why direct DHA and EPA from fish or algae are recommended rather than relying solely on plant sources.
What does research say about DHA and children's brains?
DHA makes up to 40% of brain tissue and is especially concentrated in the parts of the brain that control memory, attention, and learning.
A study published in Prostaglandins, Leukotrienes and Essential Fatty Acids shows that children with higher DHA levels in their blood perform better on tests of memory, attention, and language comprehension. A Danish study from the National Institute of Public Health confirmed a positive correlation between maternal fish consumption during pregnancy and the child's cognitive score at 18 months.
It is important to emphasize that DHA is not a magical cognitive upgrade — but a nutrient the body needs to function optimally. Deficiency has consequences. Adequate intake supports normal development.
Recommended amounts of omega-3 for children
The Danish Health Authority recommends fish twice a week — including at least once fatty fish. This corresponds to about 250-500 mg EPA+DHA daily for schoolchildren.
The Danish Health Authority's recommendations for fish are clear:
- 0-1 year: DHA is provided via breast milk (breastfeeding mothers should eat fish) or DHA-enriched infant formula
- 1-3 years: 200 g fish/week, including 100 g fatty fish (salmon, mackerel, herring)
- 4-17 years: 350 g fish/week, including at least 200 g fatty fish
By comparison: a normal portion of salmon (150 g) contains about 2500 mg DHA+EPA — far more than a child's daily requirement.
The best omega-3 sources for children
Fatty fish is by far the best and most effective omega-3 source. Salmon, mackerel, and herring contain DHA and EPA directly in the active form the body can immediately use.
Omega-3 content in selected foods:
- Mackerel (canned) — 2200 mg EPA+DHA per 100 g. Cheap and easy.
- Wild salmon — 2000-2500 mg EPA+DHA per 100 g.
- Herring — 1700 mg EPA+DHA per 100 g. Popular on rye bread.
- Sardines (canned) — 1400 mg EPA+DHA per 100 g + calcium from the bones.
- Walnuts — 9000 mg ALA per 100 g. Best plant-based source, but low conversion.
- Flaxseed oil — 55 g ALA per 100 ml. Use in dressings or add to yogurt.
- Chia seeds — 18 g ALA per 100 g. Versatile and easy to add to food.
- Algal oil capsules — direct DHA from algae. The vegan alternative to fish oil.
Supplements: when are they relevant?
Fish oil or algal oil supplements are relevant for children who do not regularly eat fatty fish — especially children on a vegan diet or with fish allergies.
Supplements are not necessary for children who eat fish twice a week. But it can be a sensible solution for:
- Children who categorically refuse to eat fish
- Children on a vegan diet (choose algal oil supplements, not fish oil)
- Children with fish allergies
When buying omega-3 supplements: check that the product specifies the DHA+EPA content (not just omega-3 in general), that it has been tested for environmental toxins, and that the dosage is appropriate for the child's age. Ask the pharmacy or your doctor.
Omega-3 and vegan diets — the challenge and the solution
Plants contain only ALA — not DHA or EPA. Children on a vegan diet should receive an algae-based DHA supplement, as algae are the primary source in the food chain that fish also consume.
Vegan diets provide ample amounts of ALA from flaxseeds, chia seeds, and walnuts, but the conversion to DHA is insufficient to meet the brain's needs. Algal oil supplements are the only plant-based source of direct DHA — and are actually more sustainable than fish oil, as fish get their DHA from algae. Find inspiration for vegan family meals on our inspiration blog.
What do you look for on the label?
Look for EPA+DHA content specified in mg per capsule — not just "omega-3". MSC-certified fish and GOED-standard marked supplements are signs of quality and purity.
Checklist when buying omega-3 supplements for children:
- DHA and EPA specified separately in mg amounts
- Age-appropriate dosing — adult supplements are typically too strong for children
- Tested for heavy metals (mercury, PCB) and dioxins
- Produced according to GOED or IFOS standards
- Taste: child-friendly supplements are available as fruit gummies, liquid with orange flavor, or chews
Omega-3 for children is simple in practice: two servings of fatty fish per week cover the needs for most children. Salmon for lunch, mackerel on rye bread, or a simple pasta dish with salmon and vegetables is all it takes.
If your child does not eat fish, an algae-based DHA supplement is a good solution. Let the child help prepare fish meals — it increases the likelihood they will eat it. Find help with this in MINI Family’s kitchen set.
Frequently Asked Questions
What is the difference between fish oil and algae oil supplements?
Both provide direct DHA and EPA. Fish oil is extracted from fish — algae oil from algae, which is what fish eat to accumulate omega-3. Algae oils are vegan, more sustainable, and equally effective. For children with fish allergies, algae oil is the right choice.
From what age can omega-3 supplements be given to children?
DHA-enriched infant formula and supplements can be used from birth. From 6 months, DHA through solid food (puree with fatty fish) is the best solution. Supplements for children under 1 year should always be agreed upon with the health visitor or doctor. From 1-2 years, age-appropriate omega-3 supplements are available in Danish stores.
Are walnuts enough to cover children's omega-3 needs?
No — walnuts provide ALA, but the body only converts 5-10% to EPA and less than 4% to DHA. Walnuts are good as a supplement but insufficient as the sole omega-3 source. Children who do not eat fish should have a DHA supplement.
Does tuna contain a lot of omega-3?
Tuna contains omega-3 — but much less than salmon, mackerel, and herring. Canned tuna in water is lowest in omega-3 due to processing. Additionally, some tuna contains more mercury than fatty fish — the Danish Veterinary and Food Administration recommends limiting tuna intake to a maximum of once per week for children.
Can too much omega-3 be harmful to children?
Very large doses of omega-3 (well above the recommendation) can thin the blood and increase the risk of bleeding. But with normal dietary amounts and standard supplements, there are no known side effects. Follow the dosage recommendation on the supplement and consult your doctor if in doubt.