Oily fish can help reduce car pollution health risks

EATING plenty of salmon, sardines and mackerel protects the brain against the toxic damage of air pollution, according to new research.

Omega-3 fats in oily fish stave off mental decline caused by fumes from transport and industry, say scientists.

Older women who ate more than one to two servings a week of baked or broiled seafood counteracted the effects of smog on grey matter.

It could reduce the risk of Alzheimer’s disease and other forms of dementia.

Lead author Dr Ka Kahe, of Columbia University in New York, said: “Fish are an excellent source of omega-3 fatty acids and easy to add to the diet.

“Omega-3 fatty acids have been shown to fight inflammation and maintain brain structure in ageing brains. They have also been found to reduce brain damage caused by neurotoxins like lead and mercury.

“So we explored if omega-3 fatty acids have a protective effect against another neurotoxin – the fine particulate matter found in air pollution.”

Participants living on busy roads with the lowest levels of omega-3 fatty acids in their blood had fewer neurons than those who consumed more.

Once controversial, the theory dirty air damages the brain is gaining traction. It has been known since the 1970s it increases the risk of heart and lung diseases.

The effect on cognition has been less well understood. But evidence is mounting. High levels have been linked to poor cognitive abilities in children.

They have also been found to increase adults’ risk of cognitive decline – and possibly contribute to depression.

The latest findings are based on 1,315 women with an average age of 70 who did not have dementia. They completed questionnaires about diet, physical activity and medical history.

The average weekly amount of fish each individual consumed was calculated, including broiled or baked, canned tuna, tuna salad, tuna casserole and non-fried shellfish.

Fried fish was not included because research has shown deep-frying damages omega-3 fatty acids.

Blood tests measured the amount of omega-3 fatty acids in their red cells. The women were then divided into four groups based on their omega-3 fatty acids.

Home addresses were used to work out their three-year average exposure to air pollution. Participants then underwent MRI scans to measure various areas of the brain. Those with the most omega-3 fatty acids had more white matter than those with the least – 410 cubic centimetres (cm3) compared to 403 cm3.

Dr Kahe added: “Our findings suggest higher levels of omega-3 fatty acids in the blood from fish consumption may preserve brain volume as women age and possibly protect against the potential toxic effects of air pollution.”