Vegan diets and omega-3s – are we getting enough?
By Elena Holmes BSc, PGDip Nutritional Therapy, MSc Nutritional Therapy (pending)
‘Where do you get your protein?’ ‘But what about iron?’ ‘Are you sure you get enough calcium?’ – I challenge any vegan to say that no one has asked them at least one of these questions before. And we all know the answer – actually, many versions of the same answer – ‘it is not a problem, I get “A, B, C” from “a, b, c” etc. But what about our omega-3s?
What are omega-3s?
Omega-3 is an umbrella term for the three essential types of fat or, to be more specific, polyunsaturated fatty acids (PUFAs). These PUFAs are alpha-linolenic acid (ALA) and its longer-chain derivatives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The term ‘essential’ means that our body cannot produce it and, therefore, has to get it from food or through supplementation. We get ALA from foods like flaxseed, walnuts, chia seeds, rapeseed oil as well as – in much smaller amounts – dark leafy greens. In our bodies ALA is converted into EPA and then DHA. Pre-formed EPA/DHA are found mainly in some microalgae, fish, molluscs and shellfish.
The other essential PUFA is omega-6, or linoleic acid (LA). It is abundant in all seeds, nuts and plant-based oils, such as sunflower, safflower, soybean or corn oil.
Why are EPA/DHA important?
These long-chain fatty acids are paramount for heart and blood vessel health because of their anti-inflammatory, blood lipid and blood pressure regulating effects. They also help in preventing or managing other inflammation-related conditions, such as asthma, psoriasis, osteoarthritis, rheumatoid arthritis, certain cancers, dry eye syndrome, age-related macular degeneration and depression. DHA, being one of the main components of the brain, decreases the likelihood of cognitive decline and neurodegenerative diseases and is also critical for good pre- and post-natal development.
The signs of low DHA
Dry, scaly skin, high levels of ‘bad’ (LDL) cholesterol, concentration problems, or depression are just a few of the signs of possible DHA deficiency or suboptimal amounts in the body.
Does a vegan diet protect us from DHA deficiency?
A wholesome vegan diet – based on fresh fruit and vegetables, pulses, wholegrains, nuts and seeds with very little or no added sugars and processed foods – provides ALA (which your body converts to EPA/DHA) and has been proven to be heart-healthy and anti-inflammatory. The components of such diet – fibre, B group vitamins (except B12), antioxidants, such as vitamins C and E, carotenoids and flavonoids as well as low consumption of saturated and hydrogenated fats – protect and support the health of the nervous system as well.
How much omega-3s should we get?
The current UK dietary guidelines recommend consuming 0.45 g/day of EPA/DHA. This is a very small amount but it is important to our health.
At least five per cent of the ALA we eat is converted into EPA and with a sufficient dietary intake of ALA (see below) this long-chain fatty acid poses little concern. During the next step, 10 per cent of EPA is converted to the final product, DHA (some authors provide slightly higher numbers, up to 25 per cent, but the majority agrees on 10 per cent).
How well we convert can be affected by many factors:
- Dietary omega-6 to omega-3 ratio. The ratio should be no more than 4:1, whereas in our modern Western diet, because of the abundance of processed foods and oils, it ranges from a whopping 15:1 to 20:1!
- Genes. There are individual variations in our genes, which makes us ‘better’ or ‘worse’ converters.
- Gender. Women convert more successfully because oestrogen improves the process.
- Age. The older we get, the less efficiently we convert.
- Certain dietary components. Vitamins B3, B5, B6, biotin (B7), A, C and E and the minerals magnesium, calcium and zinc improve the conversion, whereas trans (hydrogenated) fats, saturated fats and alcohol diminish it.
- Some health conditions, such as metabolic syndrome or diabetes, also reduce the conversion.
- Gut bacteria. Increasing scientific evidence about the bacteria residing in our gut (microbiota) shows that they actively participate in many metabolic processes and the species present can strongly influence not only how we react to the food we eat, but also how our immune, circulatory, endocrine and nervous systems work. Research also suggests that microbiota may play a very important role in how we process the essential fatty acids.
The best plant sources of ALA
|1. Flaxseed oil||53.4|
|3. Chia seeds||17.8|
|4. Rapeseed oil||9.1|
|6. Hemp seeds||8.7|
|7. Mustard seeds||3.8|
|8. Parsley (dried)||1.9|
|9. Oregano (dried)||0.6|
|10. Blueberries (fresh)||0.3|
As you can see, the best sources by far are flaxseeds, chia seeds, walnuts and hemp seeds. These should be your ‘go-to foods’ in order to ensure your recommended daily ALA intake. A couple of tablespoons of the seeds, some walnuts and cooking with small amounts of rapeseed oil should provide you with enough ALA in a day.
What can we do?
We can improve our omega-3 levels quite easily by taking these steps:
- Ensure a sufficient ALA intake by eating ALA-rich foods, such as walnuts*, ground flaxseed* and flaxseed oil*, chia seeds*, rapeseed oil and also dark leafy vegetables, such as rocket, kale, chard, spring greens, purslane or lambs lettuce.
* Omega-3s due to their chemical structure are very unstable and lose their health properties when exposed to light and heat. Therefore it is recommended to consume omega-3-rich nuts and seeds raw, and use cold-pressed flaxseed oil on salads or add it to meals after cooking. An exception is rapeseed oil because it has a high smoke point. This means that it does not change its chemical structure and, therefore, does not lose its good properties when heated and can be used for cooking.
- Maintain a good omega-6 to omega-3 ratio in your diet by avoiding omega-6-rich oils, such as sunflower, corn, soybean, safflower, cottonseed, grapeseed, poppyseed, wheatgerm, and peanut oils and highly processed foods.
- Avoid foods containing saturated and hydrogenated fats.
- Do not smoke and reduce your alcohol intake.
- Eat foods rich in magnesium, zinc, vitamins B2 and B6. These include dark leafy greens, nuts (especially walnuts and almonds), seeds and pulses.
There is no arguing about how important omega-3s are for our health. Yet at this point there is no strong evidence that every vegan should supplement with EPA/DHA. Following the dietary advice above should provide vegans with enough EPA and some DHA. Those who need more DHA – children, women who are pregnant or breastfeeding, likewise those who may be converting less efficiently, such as the elderly (especially elderly men), vegans who eat a lot of processed foods and have an unvaried diet, smokers, and people with certain health conditions – should ‘err on the side of safety’ and consider taking an algae-based EPA/DHA supplement.