Britain's Food Standards Agency has issued new advice on eating oily fish and, for the first time, is able to recommend maximum levels at which the health benefits of preventing heart disease clearly outweigh the possible risks from dioxins. 

Based on independent expert advice the Agency recommends that men and boys, and women past child bearing age, can eat up to four portions of oily fish a week. Women of child bearing age, including pregnant and breastfeeding women, and girls, can eat up to two portions of oily fish a week.
Long-standing public health advice continues to be that people should eat at least two portions of fish a week, and that one should be oily. There is good evidence that eating oily fish reduces the risk of death from heart disease, which killed 117,500 people in 2002. On average, people in the UK eat a third of a portion of oily fish a week. Seven out of ten don't eat any at all.

Because some oily fish contain chemicals such as dioxins and PCBs, which accumulate over time in the body and could have adverse health effects if consumed over long periods at high levels, the FSA asked its expert advisers in June 2003 to examine the evidence on the risks and benefits of eating oily fish. The levels of dioxins in oily fish vary and some types, such as herring, tend to have higher levels than others, such as trout. The experts based their recommendations on people eating different types of oily fish.

Dioxins and PCBs are environmental pollutants and people accumulate them through eating foods containing fat such as milk, meat, fish and eggs. Exposure to dioxins in foods has fallen by around 70% over the last 10 years and continues to decline following the strict environmental controls that came into effect in 1992.

FSA Chair Sir John Krebs said: 'Eating oily fish is a simple way for people to reduce the risks of heart disease. But most people don't eat any. Eating just one portion of oily fish a week has clear cut health benefits. This extensive review of the scientific evidence has reduced the uncertainty about how many oily fish people can safely eat without the benefits being outweighed by the risks.

'I would like to thank Professor Jackson and the members of his expert group for their hard work and rigorous examination of the scientific evidence, which has allowed the Agency to issue this new advice.'

Alan Jackson, Professor of Human Nutrition at the School of Medicine, University of Southampton, and Chair of the expert group said: 'It was a challenge to weigh up both risks and benefits. We tried to focus in on exactly what were the benefits and risks, not just for the population as a whole, but for any particular groups. This enabled us to reaffirm the advice that everybody would benefit from eating oily fish and to conclude that any issues around high consumption were specific to women because of the possible risks to the unborn baby.'

Eating oily fish – FSA advice
Men and boys, and women past childbearing age or who cannot or are not intending to have children, can eat up to four portions of oily fish a week before the possible risks might start to outweigh the known health benefits.

Girls and women who may become pregnant at some point in their lives can eat between one and two portions of oily fish a week to get the known health benefits whilst limiting any possible effects on any children that they may have in the future.

Pregnant and breast feeding women can also eat between one and two portions of oily fish a week, and should do so not just for the health benefits to them but because oily fish also helps the neurological development of their babies. (The Agency already advises pregnant women, and women intending to become pregnant to avoid shark, marlin and swordfish and not to eat large amounts of tuna.)
Occasionally eating more than the amounts of oily fish advised by the Agency will not be harmful. Possible risks from chemicals such as dioxins are not immediate: they develop as the chemicals accumulate in the body over a long period of time.

More resources on oily fish from FSA: 

Advice on fish consumption: benefits and risks

FAQs: Oily fish advice: your questions answered