Omega-3 fatty acids are back in the health news once again, this time with some solid research indicating that they can, when consumed as part of your regular diet, help protect against Alzheimer’s by lowering levels of a specific protein that’s linked to the disease.

Researchers have found it difficult to assess the effects of diet on beta-amyloid – the peptide amino acid that is associated with Alzheimer’s – in the brain, largely because that would require invasive surgery. So for this study, the researchers checked levels of beta-amyloid in the blood, which would, to some degree, relate to levels in the brain. They questioned 1,219 people, all over the age of 65 and all free of dementia, about their diet for an average of 1.2 years, then tested their blood for beta-amyloid levels.

Once the study participants’ diets had been assessed, the researchers correlated beta-amyloid levels with the intake of various nutrients, including saturated fats, omega-3, omega-6, vitamin E and C and others. The results showed that the more omega-3 fatty acids a person consumed via their diet, the lower their blood beta-amyloid levels.

Alzheimer's

Compared with people who had an average intake of omega-3, those who consumed the equivalent of half a fillet of salmon more per week had 20 to 30% lower beta amyloid levels. This is akin to an extra one gram of omega-3 per day. Other nutrients didn’t seem to have an effect on levels.

Beta amyloid forms deposits or plaques on the brains of Alzheimer’s patients, which is why it is a good indicator of the disease. In a healthy person the amyloid also exists but not at such high levels.

“Oily fish such as salmon, trout, mackerel, sardines, and fresh (not tinned) tuna, are the best omega-3 sources, and we’re recommended to eat at least one portion a week,” says registered nutritionist Dr Carina Norris. “But if you don’t eat fish, you can find lesser, but still good, amounts in flaxseeds, rapeseed and flaxseed oil, and walnuts.”