Fish is highly valuable nutritionally, especially for the formation of healthy nervous systems in unborn babies and young children. Mercury in fish, however, can potentially harm these developing organs.
As a basic precaution and sensible compromise, it's recommended that children, pregnant women or women who may become pregnant within the next couple of years limit themselves to two fish meals a week and avoid species that tend to have higher levels of mercury.
Cutting out fish altogether is not recommended for these groups; on the contrary, it should be included in their diet.
The following recommendations from the Environmental Protection Agency (EPA) are widely accepted:
Avoid larger, longer-living predator fish e.g. shark, swordfish, king mackerel. These feed high up the food chain and so tend to accumulate more mercury in their bodies.
Eat up to two meals of other fish per week. Examples of commonly eaten fish low in mercury: shrimp, canned light tuna, salmon.
Eat no more than one fish meal per week of albacore ("white") tuna, which tends to contain more mercury than canned light tuna, which is made from smaller fish.
If no official mercury advice is available about fish caught in local lakes, rivers and coastal areas (including those caught by yourself or friends), limit yourself to one meal of this per week, and no other fish.
For children, portions should be appropriately smaller than for adult fish meals. Note that some advisories are a little more conservative when it comes to children under six years of age. The Environmental Defense Fund (EDF), for example, recommends canned tuna up to three times a month only for kids under six, and suggests eating canned salmon more often as a better alternative.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, August 2012