Fish, mercury, pregnancy & brainier kids

Some women are concerned about eating fish during their pregnancy, due to possible mercury exposure, however, researchers warn that this may jeopardize their unborn babies brain development.

As touched on in yesterday’s post, there are certain nutrients essential for complete brain development. One of these is the polyunsaturated group of fatty acids: omega 3’s, the best source of which is fish & seafood.

In a study conducted in the US, children born to mothers who ate less than 340g of seafood a week during pregnancy had a 50% greater risk of scoring poorly on tests of verbal intelligence than peers.

The above research was prompted by concerns that recommendations to pregnant women to restrict seafood intake to avoid mercury exposure might be leading to a reduced intake of nutrients that are essential for brain development.

The risks from not getting enough of the nutrients essential for brain development were much greater than the risk of exposure to small concentrations of contaminants, the researchers said.

Why is mercury found in fish?

Mercury occurs naturally in the environment, thus we are exposed to it through air, water & the food supply. For most of us, food, in particular, fish, is the main source of exposure to mercury.

The level of mercury in fish varies between fish species because of the differences in habitats & feeding patterns. Fish such as shark/flake, ray, swordfish, barramundi, gemfish, orange roughy, ling, & southern bluefin tuna tend to accumulate higher levels of mercury because they are large, live longer & are at the top of the food chain. Canned tuna has lower levels of mercury than fresh bluefin tuna since the tuna used for canning is a different, smaller species & is generally caught when less than 1 year old.

So what is a safe level of seafood intake during pregnancy?

Food Standards Australia & New Zealand define the national recommendation for fish consumption during pregnancy as 2-3 150g serves fish per week. This is recognized as a minimum recommended amount.

There are some guidelines according to the type of fish.

Number of serves of different types of fish that can be safely consumed
(Taken from http://www.foodstandards.gov.au/newsroom/factsheets/factsheets2004/mecuryinfishupdatedi2819.cfm)

Pregnant women and women planning pregnancy (1 serve equals 150 grams#) & Children (up to 6 years) (1 serve equals 75 grams #)
2 – 3 serves per week of any fish and seafood not listed below
OR
1 serve per week of Orange Roughy (Sea Perch) or Catfish and no other fish that week
OR
1 serve per fortnight of Shark (Flake) or Billfish (Swordfish / Broadbill and Marlin) and no other fish that fortnight

Rest of the population (1 serve equals 150 grams #)
2 – 3 serves per week of any fish and seafood not listed below
OR
1 serve per week of Shark (Flake) or Billfish (Swordfish / Broadbill and Marlin) and no other fish that week

# A 150 gram serve for adults and older children is equivalent to approximately 2 frozen crumbed fish portions. A 75 gram serve for children is approximately 3 fish fingers (Hake or Hoki is used in fish fingers). Canned fish is sold in various sizes; for example, the snack size cans of tuna are approximately 95 grams.


In summary:

Fish is an excellent source of protein for all people. It is low in saturated fats and high in unsaturated fats, especially omega 3 oils, and is an excellent source of iodine.
Because of this it is important that we all regularly include fish in our diet and that women in particular continue to eat fish during pregnancy.
Choose a wide variety of fish & during pregnancy be mindful of the types of fish you are eating & the quantities.
2-3 150g serves is recommended as a minimum for healthy brain development in unborn children!

For more information go to www.foodstandards.gov.au & search for “mercury”