Matthew M, 28 Oct 2017
Why are you still telling people to eat farmed fish Patrick.
Whether you’ve made a choice to be vegan for health reasons or concern for animal welfare, it can be a challenge to get all the nutrients you need from a vegan diet. This is because there are some nutrients that mainly come from animal food - for example vitamins B12 and D and essential omega 3 fats EPA and DHA. Iron can also be a problem as although it is abundant in beans, it’s easier for your body to use the iron found in meat.
While algae do contain B12 like molecule it is not all in the form that can function as B12 in the body. However, recent research has identified that chlorella does provide some active forms of B12, however some of it appears to be derived from bacteria present in the medium in which it is grown, rather than synthesized by the algae. This does mean that chlorella's B12 will be a bit hit and miss, dependent on the medium it is grown in. In a study of 17 vegetarians and vegans who were B12 deficient, giving 9 grams of chlorella daily for around 60 days fifteen (88%) subjects showed at least a 10% drop in MMA, an indicator of B12 status and at the same time, homocysteine trended downward and serum vitamin B12 trended upward. This is a modest improvement. Spirulina, on the other hand, provides predominantly pseudoB12 - 83% of its B12 in a form we cannot use. The remaning B12 may by derived from the bacteria in the growing medium. The only functional B12 that I know of in vegan foods is found in shiitake mushrooms and laver seaweed, as used in Wales to make laver bread. Nori is a type of laver seaweed. Eating these foods or supplementing 10mcg a day is the only option.
There are two forms of vitamin D – vitamin D2 is made in plants while D3 is found in animal produce and produced in the skin. Our main source of vitamin D is from sunlight acting on the skin. But you need to expose your arms and face for at least half an hour a day to make enough.
D3 is marginally more effective than D2 however the D2 used in vegetarian supplements, readily converts to D3 in the body and even D3 in supplements, while not technically ‘vegetarian’ is derived from the oil in wool.
So if you’re a vegan who doesn’t get enough sunlight as you tend to cover up or live in a cold climate, then Vitamin D is worth supplementing every day, taking in 15mcg or 600iu. In the winter double this amount may be necessary. The RDA in the UK is 5mcg but Scandinavian countries have increased this to 10mcg.
Omega 3 seed oils are processed by the body from alpha-linolenic acid (ALA) into EPA and DHA which are anti-inflammatory, cardioprotective and help to build the brain. DHA is especially important in pregnancy for development of the baby’s brain.
A major study carried out by Dr Ailsa Welch at the University of East Anglia, analysed the dietary omega-3 intake of over 14,000 people in Norfolk. One interesting finding was that dark green leafy vegetables provided a significant portion of omega 3s, as does meat among meat eaters, but not nearly as much as oily fish.
The more fish – especially oily fish – eaten, the higher the blood plasma levels of EPA and DHA, with supplement takers having very high levels. But what was interesting was that the difference in blood levels between non-fish eating vegetarians and fish-eaters was not nearly as great as expected. This was especially true in women. It may be that, if deprived of a direct source of EPA/ DHA, the body converts more from vegetable sources of ALA. One possible reason why women convert more effectively is that oestrogen may help. This would make sense from an evolutionary point of view since it is in pregnancy that these essential fats are critical.
“Until we know more about enriched sources of ALA – such as flax seeds, walnut, walnut oils, leafy, dark green vegetables – we should still be cautious as to whether you can really get enough without fish,” says Welch.
A small study last year compared blood levels of Finnish vegans and non-vegetarians. Vegans had a third as much EPA and DHA than the non-vegetarians.
There are good vegetarian sources of omega-3 including chia seeds and their oil and flax seeds and flax seed oil, both of which contain ALA. However, although ALA has been shown to have positive health benefits in its own right the issue is that not so much ALA converts into the more potent anti-inflammatory EPA, essential for the cardiovascular system and DHA, essential for building the brain.
The good news is that there are now vegetarian supplements, made from algea and seaweed, that provide both DHA and EPA. A recent review concluded “algal sources of DHA significantly improve [blood] DHA concentrations.” I consider these essential for vegans who become pregnant as foetal brain development is so dependent on adequate maternal DHA. The lack of B12 and DHA is the greatest danger of a vegan diet, most easily mitigated by supplementation.
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