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Omega 3s are a type of fatty acid that come in a variety of sizes with different lengths, from short-chain ALA to long-chain DHA and EPA. All are important for your health, but while ALA is relatively easy to get from a variety of foods, such as eggs and wholemeal bread, the largest source of DHA and EPA is oily fish.
Oily fish such as salmon, mackerel, sardines and herring are the richest dietary source of the long-chain omega 3s DHA and EPA. As fish obtain these fatty acids from the plankton they eat, wild salmon has consistently higher levels of omega 3s (20-40%) compared to farmed fish (9-26%).
Vegan and vegetarian sources of omega 3 include nuts (especially walnuts), flaxseed and its oil, rapeseed oil and hemp seed oil, as well as certain marine algae from which omega 3s are extracted to make food supplements.
Fish oil remains the best source of omega 3s, however, and a study of over 14,000 people in Norfolk confirmed that those who didn't eat fish had omega 3 intakes up to 80% lower than fish eaters. If you're on a plant-based diet, you should consider a vegan Omega 3 supplement: see 'Vegetarian or vegan' below.
Oily fish remains the best source of beneficial long-chain omega 3 fatty acids such as EPA and DHA.
However, most of us aren't getting anywhere near enough; some experts recommend an intake of 1g EPA/DHA a day, but most people in the UK only manage this in a week.
EPA and DHA – the beneficial long-chain omega 3s – have a number of authorised claims relating to heart and brain health.
Fish oil is important for a healthy circulation, and DHA and EPA contribute to the normal function of the heart (at a daily intake of 250mg), the maintenance of normal blood pressure (3g per day) and the maintenance of normal blood triglyceride levels (at 2g per day). Together, these effects may help to protect the heart and circulation from hardening and furring up.
Folklore has traditionally considered fish a 'brain' food, and this is now supported by science. There is an authorised EU health claim that DHA contributes to maintenance of normal brain function at a daily intake of 250mg of DHA. DHA has a vital structural role in the brain, improving the fluidity of cell membranes so that electrical and chemical messages are passed more rapidly from one brain cell to another.
During pregnancy and breastfeeding, maternal intakes of DHA are particularly important for the normal development of the growing baby's eyes and brain.
Find out more about the benefits of Omega 3 fatty acids.
A desirable minimum intake of DHA and EPA long-chain omega 3 fatty acids is around 450mcg per day for general health.
Some experts suggest the higher amount of 1g EPA/DHA per day, which is equivalent to eating 2-3 medium servings of oily fish per week. Average dietary intakes of omega 3 are much lower than this, however, at 1g EPA/DHA per week.
If you're unlikely to be able to eat the recommended 2-3 servings per week, whether through dietary requirements or preference, consider an omega 3 supplement.
Omega 3 fish oil ranges can be confusing, but there are a few things you should look for to make sure you're getting the right supplement for you.
First is strength. The figure shown on the supplement's packaging (such as 500mg) is likely to refer to the total amount of fish oil in each capsule. Refer to the label to see how much of that total is the particularly beneficial DHA and EPA.
Going for more concentrated capsules (High Strength or Super Strength) can have two advantages. The first is that you may get a smaller capsule, which is easier to swallow. The second is that you could get your desired amount of DHA and EPA in a single dose, so don't have to worry about remembering your supplement twice in a day.
Next, you should select a pharmaceutical-grade omega 3 fish oil supplement made to GMP standards to ensure they are virtually free from marine pollutants.
Sustainability is increasingly important for marine products. If this matters to you, look for fish oil supplements that have been awarded Friend of the Sea or Marine Stewardship Council certification.
If you are vegetarian, vegan or allergic to fish, algae oil – made from marine algae – is a good source of EPA and DHA. A typical capsule containing 1,000mg algae oil can provide over 300mg of DHA and 200mg of EPA.
Finally, there's absorption. Omega 3 supplements offered in the triglyceride (TG) form are most easily absorbed, as they are in a 'body-ready' form. Healthspan's Opti-Omega 3 is an example, which also has a shell designed to break down in the intestine rather than the stomach, helping to reduce acid reflux and 'fishy burps'.
Fatty acids sourced from algae are an excellent alternative to fish for vegans and vegetarians. Find out more about Healthspan's Veg-Omega 3.
The European Food Safety Authority has confirmed that long-term intakes of supplements providing up to 5g of EPA plus DHA per day (or up to 1g DHA alone per day) do not raise any safety concerns.
Because of their blood thinning effect, however, people with clotting disorders or who take blood-thinning medication (eg warfarin) should seek advice from their doctor before taking an omega-3 fish oil supplement.
Dr Sarah Brewer is Healthspan's Medical Director and holds degrees in Natural Sciences, Surgery and Medicine from the University of Cambridge. Having worked as a GP and hospital doctor, Dr Sarah now holds an MSc in Nutritional Medicine from the University of Surrey and specialises in nutrition. She is also an award-winning writer and author.