A Big Fat question – do vegans get enough DHA?

Posted on 16th October 2019

 

‘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-3?

 

What is omega-3?

 

Omega-3 is an umbrella term for the three essential polyunsaturated fatty acids (PUFAs) 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. The other essential PUFA is omega-6, or linoleic acid (LA).

We get ALA from foods like linseed, 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. LA is abundant in all seeds and nuts and plant-based oils, such as sunflower, safflower, soybean or corn oil. Our body converts it into the long-chain PUFA arachidonic acid (AA or ARA).

Pre-formed EPA/DHA are found mainly in some microalgae, fish, molluscs, and shellfish. Pre-formed AA is found in meat, dairy, and eggs.

 

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 vegetables and fruit, pulses, wholegrains, nuts and seeds with very little or no added sugars and processed foods – while not providing pre-formed EPA/DHA, has been proven to be heart-healthy and anti-inflammatory. The evidence from the research about its full effects on the health of the nervous system is, however, insufficient and often contradictory.

 

How much omega-3 should we get?

 

The current UK dietary guidelines recommend consuming 0.45 g/day of EPA/DHA.

 

Conversion

 

At least 5% of dietary ALA is converted into EPA and with a sufficient dietary intake of ALA (see below) this long-chain fatty acid poses little concern. On the other hand, the conversion from ALA to its final product DHA is 2 – 10 times less efficient. Therefore, consuming 18 – 20 g of ALA per day (for example, two tablespoons of linseed oil and 35g of walnuts) should result in 0.9 g of EPA, but only 0.1 g of DHA.

How well we convert can be affected by many factors:

 

·     Dietary omega-6 to omega-3 ratio. The ratio for optimal conversion 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 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 it actively participates in many metabolic processes and its composition can strongly influence not only how we react to the food we eat, but also how our immune, heart and blood vessel, endocrine, and nervous systems work. There isn’t sufficient evidence yet on the exact role of microbiota in the metabolism of fatty acids (though there are studies showing that higher intake of EPA/DHA has positive effects on gut bacteria), but the relevance of a high variety of beneficial bacteria in our gut for efficient nutrient absorption suggests that microbiota may play a very important role in how we process the essential fatty acids.

 

The best plant sourcesfor ALA

 

 

 

Source

ALA

g/100g

1. Perilla seed oil

58.0

2. Linseed oil

53.4

3. Camelina oil

31.2

4. Linseed

22.8

5. Chia seeds

17.8

6. Rapeseed oil

9.1

7. Walnuts

9.1

8. Hemp seeds

8.7

9. Mustard seeds

3.8

10. Purslane

3.4

11. Parsley (dried)

1.9

12. Cloves

0.6

13. Oregano (dried)

0.6

14. Blueberries (fresh)

0.3

15. Cloudberries (fresh)

0.3

16. Lingonberries or cowberries (fresh)

0.2

 

 

 

What can we do?

 

We can improve our omega-3 levels quite easily by taking these steps:

 

·     Ensure a sufficient intake (18 – 20g daily) of alpha-linolenic acid by eating ALA-rich foods, such as walnuts, ground linseed and chia seeds, linseed and rapeseed oil, plus dark leafy vegetables, such as rocket, kale, chard, spring greens, purslane, or lambs lettuce.

·     Maintain a good omega-6 to omega-3 ratio in your diet by avoiding omega-6-rich oils and highly processed foods.

·     Avoid foods containing trans, 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.

 

Bottom line

 

Notwithstanding the growing evidence about the importance of omega-3 PUFAs to our health, there is still insufficient evidence to recommend that vegans take EPA/DHA supplements. 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.

 

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