You may have heard fish is good for brain health- but what’s the evidence?


By Nicola Williams | Tuesday 11 October 2022

As the saying goes, ‘You are what you eat’, and just like other parts of the body, our brains can be affected by the way we live our lives, including our diet.  

Research shows up to 40 % of dementia cases could be linked to factors we can influence – and this includes eating a balanced diet. 

But where do individual foods come into play? And, given recent headlines about research linking omega-3 fatty acids in our diets to better brain health, should we be piling our plates with oily fish or rushing to buy omega-3 supplements?  

A balanced diet helps our heart and brain

Heart and blood vessel health can have a large impact on brain health. Our brain relies on a constant supply of oxygen and sugar from our blood to function. It also needs to clear waste and send messages to other parts of the body via chemicals called hormones.  

Research has shown that heart disease or damaged blood vessels (for example following a stroke) increase a person’s risk of dementia. Therefore, reducing the risk of heart and blood vessel diseases helps to keep our brains fighting fit too.   

A balanced diet, including sources of omega-3, can help protect our heart health, which in turn will be good for our brains. Eating fewer foods high in saturated fat, such as red meat and dairy products, helps lower risk of heart disease by reducing harmful cholesterol build-up in the arteries.  

What is omega-3? 

While some foods like oily fish contain some saturated fat (we do need a small amount), they also contain omega-3, which are unsaturated fats and are less likely to raise so-called ‘bad’ cholesterol levels.  

But what exactly is omega-3?

The name refers to a group of similar oily substances called fatty acids, found mostly in oily fish like mackerel and salmon. Some plant-based foods, such as seaweed, chia and flax seeds, also contain some types of omega-3, although these can be different to the omega-3 found in fish. We cannot make omega-3 ourselves, so we must get it from our diet. By eating fish regularly as part of a balanced diet, we can get the all the omega-3 that we need.  

Are omega-3 fatty acids really good for us? They are popular health supplements, but scientists are still trying to understand whether they really do have benefits. For example, a lot of research has explored their role in reducing risk of heart disease, with a recent evidence review concluding that although they “slightly reduce risk”, the effects seem to be very small.  

What about omega-3 and brain health? 

Researchers have been studying how omega-3 affects the brain and dementia risk for many years, and while the picture is similarly incomplete, there are tentative positive signs. For example, a study from November 2021 found that people who ate fish more regularly had healthier blood vessels, which could, in theory, reduce risk of Alzheimer’s and vascular dementia – although the study didn’t directly measure this.

There is also some evidence that omega-3 can improve some aspects of brain health. A study published earlier this month showed that people in midlife who had higher levels of omega-3 in their blood had higher scores on thinking tests and healthier brain structures than people who had lower omega-3 levels.

But there’s still a way to go before we can prove omega-3 can protect our brain health. This recent study – as with so many – is “exploratory, not conclusive”, according to Dr Sara Imarisio, Alzheimer’s Research UK’s Head of Research:

“Research into omega-3 and brain health has produced mixed results,” she says, “and while this study adds to the evidence base it only looked at people in middle age, this study only offers a snapshot of the full story.”

This last point is crucial: the study wasn’t set up to follow whether people went on to develop conditions like dementia, so there’s more research to be done on this link. To find out whether these apparent effects on brain health could translate into reduced dementia risk, the researchers will need to follow up on the study participants as they age.  

Beyond this study, researchers are focusing on the effects of eating fish regularly or adopting a diet containing more omega-3, rather than studying omega-3 on its own. Researchers are also exploring whether the Mediterranean diet- rich in fruit, vegetables, fibre and sources of omega-3 like fish- could boost heart and brain health.  

Prof Anne-Marie Minihane at the University of East Anglia is investigating how adopting regular exercise and a Mediterranean diet over six months affects people at higher risk of heart disease and dementia. Prof Minihane spoke about her project, which is funded by Alzheimer’s Research UK, in our recent online Lab Notes talk. 

You might be wondering about the effects of taking omega-3 supplements, like cod liver oil capsules. Unfortunately, there’s still not much concrete evidence as to whether these can help protect brain health, and research into supplements and dementia risk is still ongoing. 

Overall, the exact role of omega-3 in dementia risk is still unclear. However, if you are torn between a greasy cheeseburger or a salmon supper, your heart and brain might thank you for choosing the fish.   

So, what’s the bigger picture? 

While we still don’t fully understand all the benefits of omega-3 for our brain health, we do know is that as part of a healthy balanced diet, there are promising signs that omega-3 helps our general health, in turn helping our brain.  

The NHS recommends that we should eat around two portions of fish a week, one of which should be oily. It’s a good excuse to try out a new recipe, perhaps! 

Remember – our brain health depends on many factors, some of which we may be able to influence, whilst others we cannot change. We do know that loving our heart, staying sharp and keeping connected are all ways to protect our brain health. Eating a balanced diet is one way to achieve this, alongside an active lifestyle and healthy social connections. 

Find out more about our brain health tips.


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Nicola Williams