One of the fundamental pieces of dietary advice given in the UK is to eat two portions of fish a week, one of which should be oily fish. There are several reasons for this, but one of them is that oily fish is a good source of omega-3 fatty acids.
You can also get these fatty acids from plant sources, though it’s not as easy for the body to absorb them in this form. You can also get them from supplements. For more information on why omega-3 fatty acids are important and how to go about getting them, we spoke to registered nutritionist (RNutr) Rhiannon Lambert.
What is omega-3?
It’s an example of unsaturated fat, and there are three main types of it: alpha-linoleic acids (ALA); docosahexaenoic acid (DHA), which is the really important one; and EPA, which is eicosapentaenoic acid. ALA is mainly found in plant-based sources, while DHA and EPA mainly come from animal sources.
DHA is the one that we really need to be getting enough of. It’s actually the most abundant form in the body – 60% of our brain is made up of fat, and that’s predominantly those DHA fatty acids. Omega-3 plays a role in our cell structure. The outside coating of a cell is the cell membrane, which retains the structure, and you need these fatty acids to build those membranes.
What are the established benefits of omega-3?
The key research is on brain health, and a lot of it is on Alzheimer’s disease. You’ve got the umbrella term dementia, Alzheimer’s comes under that, and we’ve got a lot of research that with neurodegenerative diseases, perhaps dietary interventions can slow it down or reduce the risk.
There’s also a tonne of research that it’s beneficial for cardiovascular health. Fertility is another area as well – eating a Mediterranean diet which contains omega-3s has been linked to fertility.
They’re the key areas that we have a lot of research in. But it’s important to add, it’s still evolving. The brain is a difficult area to study, and there are lots of areas linked to brain health, but omega-3 is one pathway that we can look at.
We’ve covered Cochrane reviews of the available evidence suggesting that omega-3 has a limited impact on heart health. What’s your view on that?
What we can take from it is that we still don’t have a full understanding of omega-3 and messages can be mixed. The UK still promotes eating it for heart health, but there is some evidence that does suggest otherwise. Ultimately there is no harm in consuming omega-3 and there is enough evidence to suggest in other areas that it can be beneficial.
Is there any guidance on how much omega-3 you need?
We’re advised to eat two portions of fish a week, only one of which is oily. This is because of the levels of mercury in fish in the sea now.
When it comes to advising how much omega-3 we need, it’s a very grey area. There’s no official guidance in the UK on omega-3 itself, especially in supplementation forms. In America, they say a minimum of 250 to 500mg of combined EPA and DHA for healthy adults daily. So that’s a rough guideline. The American recommended daily allowance of ALA is 1.6g a day for men and 1.1g for women.
In the UK, we do advise that for children, boys can have more portions of oily fish than girls – boys could have two, girls could have one. That’s because of the potential impact on fertility for women with the stored minerals in their body from the pollutants that are found in fish.
What are good dietary sources of omega-3?
The key sources are oily fish, but if you don’t consume them, then nuts and seeds. Meat does have some omega-3, but it’s not known as a really good source. Some fish are higher in omega-3 than others – fish like sardines, salmon, mackerel are higher than white fish like sea bass and sea bream.
There is also algae. Most people know omega-3 comes from oily fish, but the fish eat the algae in the sea, which contains DHA, and we consume the fish that eat the algae. So if you’re a vegan, you can just take the DHA algae and cut out the middleman.
The reason we want fish, though, is because we absorb DHA really well when it comes from fish. When we’re simply getting the plant-based form ALA – which you get in things like avocado, nuts and seeds – we don’t absorb it very well. It takes a very long time to convert in the body to DHA and EPA.
Are there different types of omega-3 supplements?
Yes there are. You want to be looking for EPA and DHA in a fish oil supplement, and you can also get things like krill oil that will contain omega-3.
Vegans can have DHA in algae form if they don’t feel comfortable taking the oily fish, and actually, it’s often higher-quality these days anyway, because the quality of fish oil can vary greatly.
Can you have too much omega-3?
You can have too much, and pregnant women shouldn’t be taking it on top of a vitamin A supplement.
In the UK we don’t have recommended amounts but the European Food Safety Authority, which we use, says up to 5,000mg is safe in a dose. However, the FDA, which is the Food and Drug Administration in the USA, says you shouldn’t exceed 3,000mg a day. That’s because of the risk of excessive bleeding and blood thinning. The advice is mixed but it’s not good to take too much of anything.
I would always say speak to a health professional before taking a supplement, especially if you’re pregnant.
How does omega-6 relate to omega-3?
We have insufficient evidence about the impact of omega-6, but it’s believed that like with cholesterol, there’s a ratio of good and bad. You want more omega-3 and less omega-6, because it’s thought that if the ratio is the wrong way around, it can create inflammation in the body. But inflammation in nutrition is very blurred and confused as it is. There is no miracle food that you can eat and suddenly expect to have no inflammation in your body.
We spoke to Rhiannon Lambert around the launch of the Nutri Within supplement range at LloydsPharmacy