Researcher Network member, Elena Holmes, discusses her research into omega 3 fats and vegan health for our Health & Wellbeing Portfolio.
One of my main areas of interest is the conversion of an omega-3 fat, called alpha-linolenic acid (ALA), to a long-chain omega-3 fat, called docosahexaenoic acid (DHA). The rapidly increasing body of evidence suggests that DHA is vitally important for the health of our heart, blood vessels, brain, and nerves, as well as for efficient functioning of the immune system. DHA is present mainly in fish and shellfish, but can also be found – in much lower levels – in meat, eggs, and dairy. It is also present in some types of marine microalgae (this is where fish and shellfish get their DHA from). Vegans, unless they take algae supplements, do not consume pre-formed DHA. And yet not everyone who completely excludes dietary DHA experiences DHA-deficiency-related symptoms, such as heart and blood vessel disease, dry scaly skin, or depression.
(My research interest focuses specifically on DHA because the conversion from ALA to another long-chain omega-3 fat called eicosapentaenoic acid (EPA), the ‘intermediate’ between ALA and DHA, is much more efficient and therefore raises less concern from a clinician’s point of view.)
There is sufficient evidence that a wholesome – as opposed to ‘junk’ – vegan diet can be protective against heart and blood vessel disease because it helps to regulate fats in our blood, like cholesterol, and reduce inflammation. But how do we explain the absence of other DHA deficiency-related symptoms in even some ‘long-term’ (>10years) vegans? Do vegans convert the dietary ALA to DHA better? And if they do – is it because a vegan diet contains lots of substances that improve conversion, such as magnesium or vitamin B6? Or is it because of their low dietary intake of substances that have a negative impact on conversion, such as saturated fat or trans-fats? Or both? Do the gut bacteria found in people following vegan diets have some effect on the efficiency of conversion?
Research involving vegans is still limited, although quickly growing, and the opinions of nutrition experts range from: ‘some vegans would benefit from taking DHA supplements’ (A. Saunders; B.C. Davis) to: ‘there is not enough evidence to suggest that vegans should take DHA supplements’ (Prof T. Sanders).
I am fascinated by these questions, both as a researcher, because of my scientific curiosity, and as a practising nutritionist, because of these questions clinical relevance.
- The ALA to DHA conversion is influenced by multiple dietary and individual factors
- All vegans could optimise the ALA to DHA conversion by: 1. consuming at least 2-2.5 g/day of ALA from food (e.g. walnuts, ground linseed, linseed oil, rapeseed oil, and dark leafy greens); 2. reducing their intake of the omega-6 fat linoleic acid (abundant in margarines, vegetable oils, many bakery products, and meat substitutes); 3. ensuring that their diet is rich in bioavailable magnesium, zinc, and B group vitamins (by eating pulses, dark leafy greens, nuts, seeds, and wholegrains). These nutrients improve the ALA to DHA conversion.
Considering the seriousness of the diseases that may be related to DHA deficiency or suboptimal levels in the body (depression, age-related macular degeneration, or Alzheimer’s), my personal advice, as a nutrition professional, for the vegans who need to be careful about their DHA levels (such as the elderly, and particularly elderly males, children, those who are pregnant and breastfeeding, and those who do not have a sufficient intake of ALA [2-2.5g/day]) would be to err on the side of caution and consider taking an algae EPA/DHA supplement.
Read more about Elena's Researcher Network profile here.
A note from Heather Russell, Dietitian for The Vegan Society:
“We need more research around omega-3 fat status in vegans and the effects of microalgae supplementation on vegan health. Although it’s not thought to be essential for vegans to add long-chain omega-3 fats to their diets by taking a microalgae supplement, it’s a more important consideration during pregnancy, breastfeeding and childhood due to the role of these fats in brain, nerve and eye development. Our nutrition zone provides further advice about omega-3 fats.”
The views expressed by our Research News contributors are not necessarily the views of The Vegan Society.