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A Guide to Omega-3 Fats
When there is talk about fats, omega-3 fats get a lot of press. They seem to be the main reason for us to eat fish. “Omega-3” is sometimes printed on egg cartons. You can buy them as supplements. But what’s so special about them? How are they different from other fats? Are there different kinds of omega-3? Are omega-3s the only good fats and are other “omegas” bad? Here’s our guide to omega-3s.
Omega-3 fats have crucial functions to fulfil around the body. They are part of every single cell wall, are a major building block of the brain, help lubricate our joints, keep our blood runny and modulate inflammatory processes. We must make sure to have adequate levels of these fatty acids.
Saturated, monounsaturated, omega – The science bit…
There are different types of fats: saturated (SAFA), monounsaturated (MUFA) and polyunsaturated fats (PUFA). Omega-3 and omega-6 fatty acids belong to the latter group.
Fatty acids are molecules that consist of chains of carbon atoms dotted with hydrogen and a tail end called the “acid group”. Each carbon atom only has a limited number of “ports” for hydrogen to bind to. When all of those spots are taken, we’re looking at a saturated fatty acid. If they are not, it’s unsaturated fatty acid: monounsaturated if there’s only one vacancy, polyunsaturated if there are more. The polyunsaturated fats are the omega fats: omega-9 (monounsaturated), omega-6 and omega-3 (polyunsaturated). The number tells us where along the length of the chain the first vacancy occurs.
These vacant sites give the fatty acid a kink and makes it a little more flexible. Picture it like your shoulder joint that allows your arms to point in almost any direction. The more kinks, the more flexible the fatty acid, the runnier the oil and the more sensitive to damage it is going to be. Saturated fats, on the other side of the spectrum, are stiff, creating a fat that is solid at room temperature (think butter or coconut oil). They are much hardier and have a longer shelf-life.
We do need all of them, even the much-maligned saturated fats. Every single cell wall in our body contains all types of fats. Cell membranes need saturated fats to keep them stable and unsaturated fats to keep them fluid – as a cell membrane needs to be both.
Omega-6 and omega-3 are the “essential fats”. In nutrition, when something is referred to as “essential” that means that we must eat it, the body cannot make it. As long as we eat any kind of fat, our body can create saturated and monounsaturated fats as needed. Not, however, omega-6 or omega-3.
Plant vs Animal Omega-3
In theory, the only genuinely essential omega fats are the plant-derived omega-3 alpha-linoleic acid (ALA) and omega-6 linolenic acid (LA). They are the respective bottom rungs of two omega ladders. The omega fatty acids higher up the ladders get ever longer and more unsaturated. The body can convert ALA and LA “up the ladder”, which is necessary as different omega fats have different jobs to do around the body.
The diet provides omega-3 fats from both vegetable (e.g. flaxseed, pumpkin seeds, walnuts, hemp seeds and their oils) and animal foods (e.g. meat and dairy products from pasture farming, eggs, fatty fish), but these fats are not the same. The types of omega-3 we need the most are the long-chain fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA is required to produce anti-inflammatory compounds, DHA for nerve cells and the brain. The short-chain omega-3 fatty ALA from plants, must first be converted into EPA and DHA in the animal (including human) body.
In humans, this transformation is not particularly efficient. Only about 5 – 9% of the ALA consumed actually becomes EPA. Moreover, this process is very fickle and can be interrupted by inflammation, poor diet, disease and stress. Furthermore, omega-3 and omega-6 fats compete for the same enzyme between the first and second rung of the ladder. If there is considerably more omega-6 than omega-3, omega-3 hardly gets a look-in.
For this reason, people choosing a vegan diet can struggle to get sufficient quantities of EPA and DHA, even if they are adding extra linseed or walnut oil to the diet. Seaweed is one source, as unlike land plants, seaweed already contains ready-made EPA and DHA, but gram for gram, it does not provide much: 100 g of seaweed contains just 0.3g of fat in total, 0.1g of which is omega-3. Even if the problem of conversion did not exist, it is challenging to cover your daily requirements from plant sources alone. (Supplement companies now sell vegan DHA/EPA supplements for vegans who are concerned about their omega 3 intake).
Animal foods contain EPA and DHA, as the transformation has already taken place in the animal’s body. The tissue of cold-water fish is particularly rich in fat for better insulation. The fish obtain their omega-3 from algae and from smaller fish that are their prey. At our end of the food chain, humans benefit from the long-chain omega-3 fatty acids.
What about Omega-6?
Omega-6 is essential, too, so why is everyone always just recommending omega-3? That’s because the modern Western diet contains plenty of omega-6 – possibly even too much. It is the dominant fatty acid in grains and many nuts and seeds, e.g. peanuts, soya and sunflower. As most meat and dairy comes from cattle fed on grains and soya and because seed oils are widely used, at home as well as in food processing, omega-6 deficiency is rare. The ideal omega-6:omega-3 ratio is 1:1 up to 4:1. Most of us have ratios of over 20:1. It is for that reason that you rarely hear anyone recommending an omega-6 supplement although there are exceptions. The omega-6 fatty acid GLA, for example, is the dominant fat in evening primrose oil, which has been found useful in balancing hormones.
It is important to remember that we need all fats. We just don’t necessarily need to eat all the different kinds as all but the omega-6 and omega-3 fats can be manufactured in the body. The only kind we do not need are trans-fats. These are unsaturated fatty acids which, due to their chemical structure, behave like saturated fats (i.e. they are solid at room temperature). Yet because they are artificial, our body does not know what to do with them and they are unable to perform the jobs of natural fats. Transfats have been found to be carcinogenic and are banned in many countries. They are found in hardened vegetable oils (“partially hydrogenated”), processed foods and repeatedly heated plant oils (think anything deep-fried: crisps, chips, onion rings, chicken).
If you are curious about the fatty acid composition in your diet, ask us about a fatty acid test. A variety of omega-3 supplements is available, including vegan ones derived from seaweed.
Please click here for details of our webinars, including Mental Wellness, which talks in more detail about omega-3 fats and brain health.