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In the UK, only a quarter of UK adults eat any oily fish, with less than 16% of young adults eating two or more portions of fish a week.

Oily fish are a group of fish high in healthy fats, and crucially, a great source of Omega-3s. There are two types of Omega-3 fatty acids that you can get through fish – DHA and EPA. Your body isn’t good at making these essential fatty acids so you have to ingest them. You may have heard a lot about the benefits of upping your Omega-3 levels, so what’s the evidence behind it?

A surprising discovery

One of the first hints of the benefits of Omega-3 fatty acids came from studies in the 1970s looking at Inuit populations in Greenland whose diet contained plenty of seal and fish. Despite their high consumption of fat and the almost complete absence of vegetables in their diet, these people had a particularly low incidence of heart disease.

Food for the heart

Since these initial observations there have been thousands of studies looking at the effect of Omega-3s on cardiovascular health. One recent large study of more than half a million British men and women found that high Omega-3 intake was associated with a 16% lower risk of death from heart attack or stroke.

Omega-3s have been shown to reduce the spike in blood fats after a meal, and they improve the stability of plaques in blood vessels, making them less likely to rupture. Omega-3s can also regulate the thickness of blood in your body.

Plus, they are thought to have powerful anti-inflammatory effects, which can reduce chronic inflammation in your body. This is important not only for your heart and blood vessels, but also your brain health.

Studies of different societies have consistently found that people who eat more fish tend to suffer less from neurodegenerative conditions like dementia. Eating oily fish has also been linked to bigger brains! When researchers compared a group who ate fish weekly and a group who didn’t eat fish at all, they found the fish-eaters had larger brain volumes – mostly in their frontal lobe, which is important for focus, and in their temporal lobes, crucial for memory, learning and cognition.

Brain health, walking speed and Omega-3s

"Walking speed is a good indicator of brain health," Dr Simon Dyall from Roehampton University explains. It is a very complex task that takes a lot of brain capacity. In his clinical trial, older women were given Omega-3 supplementation for six months. Those in the treatment group were found to walk slightly faster at the end of the trial than the beginning – just by increasing their levels of Omega-3s! Furthermore, important measures of cognition improved, like verbal memory and reaction time.

These exciting preliminary results suggest that Omega-3s could benefit mobility and age-related brain health! So, how does it work?

Feed your membranes

Dr Dyall explains on the Just One Thing podcast that the two Omega-3s you can get from oily fish, DHA and EPA, are particularly important fatty acids for the brain. Amazingly, the brain is about 60% fat, and of that, 10-12% is DHA. When you consume Omega-3 fatty acids, they get incorporated into the membranes of your cells, and improve their function.

Omega-3s are also involved in a process called neurogenesis which is the making of new brain cells, as well as gene regulation. “They have profound effects on the functioning of the cell, potentially related to the enrichment in the cell membrane,” says Dr Dyall.

Some studies suggest that the effect of Omega-3s on your brain may even help protect you against the effects of air pollution! One study of older women found that one to two servings a week of fish was linked to larger brain sizes, despite the potential toxic effects of air pollution.

But which are the best types to eat, and how much should you eat?

SMASH it

Here’s a handy acronym to remember the different types of oily fish: SMASH. That’s salmon, mackerel, anchovies, sardines and herring.

Generally, two portions of oily fish a week is a good amount to aim for.

“The more that can be done to preserve the Omega-3s from heat, oxygen or light, the better. Freezing is a great way of doing this,” says Dr Dyall.

But if you don’t fancy adding fish to your menu, there are some good alternatives.

The OG source

What’s fascinating is that fish don’t make the Omega-3s we need, they consume it from algae. So, if you don’t want to eat fish, you can get it from the source! Algal supplements are a good source of EPA and DHA.

All of these different methods can be great ways of topping up your Omega-3s. Whether you’re enjoying some smoked mackerel, or trying out some supplements, it’s a simple change that can reward you with a wide range of wonderful benefits.

To find out more about the benefits of Omega-3 and oily fish, listen to the Enjoy Oily Fish episode of Just One Thing on 麻豆社 Sounds.