What are the nutrients in fish that make it a brain food?

Docosahexanoic acid (DHA), an omega-3 fatty acid, is one of the components of brain tissue. DHA may influence neurotransmitters in the brain, helping brain cells to communicate better with each other. The brain is made up of more than 50% fat, 25-35% of which is made up of the essential fatty acid DHA.

“DHA-rich food sources include human milk, cold water fatty fishes such as salmon, tuna, sardines and mackerel. Other sources include seafood like oysters and shrimps,” says the Department of Nutrition and Dietetics at KK Women’s and Children’s Hospital, a member of the SingHealth group.

Methylmercury in fish: points to note

In recent years, there have been concerns about the levels of methylmercury in fish, especially the effect on foetal development, infants and children.

Methylmercury exposure can adversely affect a baby's growing brain and nervous system, leading to effects on the child’s:

  1. cognitive thinking,
  2. memory,
  3. attention span,
  4. language skills,
  5. fine motor skills and
  6. visual spatial skills.

Hence, the US Food and Drug Administration (FDA) recommends to have 1 to 2 serves of fish a week, from the age of 2 years (1 serve = 2 ounces for children 4 to 7 years, or 4 ounces for older children).

In addition, the US FDA also recommends that infants, young children and pregnant women avoid the following fishes with high mercury levels:

  • Swordfish
  • King mackerel
  • Spanish mackerel (Batang), which can be consumed safely when limited to 1 serve a week.
  • Shark
  • Tilefish
  • Big eye tuna
    • ​Other varieties of tuna are lower in mercury.
    • ​​1 serving of yellow fin and albacore (or white) tuna can be consumed once a week, and canned light tuna (including skipjack) can be consumed 2 to 3 times a week.
    • If you are uncertain of the type of tuna in your canned tuna, limit to one serving a week.

Is there any special cooking method to retain the nutrients in fish?

Omega-3 fatty acids are relatively stable in whole foods. However, deep-frying the fish may destroy the Omega-3 fats significantly. Baking, broiling and steaming causes minimal Omega-3 fat losses. 

For overall good health (both for obesity prevention and for heart health), it is encouraged that foods be prepared using healthy cooking methods such as

  1. boiling,
  2. steaming,
  3. pan-frying
  4. baking and
  5. grilling.

It is also important to cook using mono-unsaturated or polyunsaturated oils, e.g. olive, canola, sunflower, soybean, peanut and rice bran.

Other sources of Omega-3

If your child does not eat fish or is vegetarian, he can obtain plant sources of omega-3 fatty acids, known as alpha-linolenic acid, mainly from canola oil, soybean oil, linseeds (flaxseeds) and walnuts.

If you decide to use a supplement, be mindful of the following:

  1. Choose a supplement that is appropriate for your child’s age. Always check the instructions on the package and do not exceed the suggested dosage.

  2. Avoid giving capsules for children under 3 years of age as they are a choking hazard. Omega-3 supplements now come in gummies or liquid form.

  3. Purchase supplements made from refined oils from the flesh of fish instead of fish livers. Cod liver oils, commonly consumed by many toddlers in Singapore, contain fish oil, vitamin D and pre-formed vitamin A (retinol). Pre-formed Vitamin A (retinol) is fat-soluble and excessive intake can lead to dizziness, nausea, headaches, coma and even death. Different br​ands contain varying amounts of Vitamin A. The Singapore Recommended Dietary Allowance​ (RDA) is 250 mcg for children aged 1 to 2 years, 300 mcg for 3 to 6 years, 400 mcg for 7 to 10 years and 575 mcg for 10 to 12 years.

  4. If your child is vegetarian, you can consider offering an omega-3 supplement made from microalgae oils.

Ref: O17