Sardines shoal Rich Carey

The NHS says a healthy, balanced diet should include two portions of fish a week, including one of oily fish.

Be mindful of what you're eating

Oily fish- things like mackerel, herring and sardines- are a particularly good source of Omega-3 fatty acids. Fish don't make Omega-3 themselves, it's made by plankton. Forage fish, like herring and sardines eat lots of plankton and the Omega-3 builds up in their bodies through a process called bioaccumulation.

This is great news for us, as it saves us from having to eat tons of plankton, but other, less desirable compounds can also bioaccumulate in ocean food webs.

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Mercury and other heavy metals pass up and up the food web and many top predators like sharks and billfish contain levels of contaminants that can be harmful to pregnant women and their babies.

We wouldn't recommend eating sharks for sustainability reasons- most of them are red-rated on the Good Fish Guide, but a single portion of shark or swordfish can contain enough mercury to be harmful to a foetus.

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For this reason, there is specific advice for consuming certain seafood:

  • Girls, pregnant women, those that want to get pregnant one day and breastfeeding women should limit their consumption of oily fish (as well as sea bream, sea bass, turbot, halibut, 'rock salmon' and brown crabmeat) to two portions a week. Everyone else should limit consumption of these to 4 portions a week.
  • Pregnant women or those trying for a baby should limit their consumption of tuna to four cans or two tuna steaks a week.
  • You should vary the species of fish you are consuming, because different species have different levels of pollutants.
  • There are limits for everyone on the consumption of shark/swordfish/marlin of one portion a week, although children, pregnant women or women wanting to get pregnant shouldn’t consume any of these.
  • Anyone can consume unlimited amounts of white fish other than sea bream, sea bass, turbot, halibut and 'rock salmon', without concerns for their health. But bear in mind concerns for our sea and check the Good Fish Guide.

For further information, please visit the NHS website.

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