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A vegetarian or vegan diet, if well-balanced, can provide the body will all essential elements, except for vitamin B12, which must be taken in the form of a supplement.

For vitamin D, the most common deficiency among the general population is generally found in vegetarians/vegans, and a supplement is also indicated in the same way.

However, if these diets are not varied and balanced enough, the risk for those who adopt them is real. They may give rise to low levels or deficiencies in several vitamins, minerals or trace elements that play key and sometimes decisive roles in balancing the body and keeping it in good health.

Trace elements to be monitored

Iron

Although iron consumption in vegetarians and vegans is at first glance higher than that of omnivores, due to their higher plant consumption, the iron they consume is non-haem, a form in which bioavailability is lower (2 to 10%) than that of haem iron present in meat, fish and shellfish (bioavailability = 40%). Even though anaemia is not very common in vegetarians/vegans, a ferritin assay is one of the tests to be carried out.

Iodine

As iodine is present in dairy products, a vegetarian does not run the risk of a deficiency. However, it is virtually absent from plant-based foods and while iodised salt or seaweed consumption provides iodine for vegans, a supplement may be necessary because there is still little known about the iodine content of these foods and the required amount is not always provided. Biological confirmation of a deficiency is obviously necessary before considering a supplement.

Zinc

Low to moderate zinc deficiency is common, especially in people who consume few foods of animal origin in favour of plant-based foods, all the more so because the latter are rich in phytates which interfere with its absorption (oats, bran and wheat cereals, soybean sprouts, wheatgerm, sesame seeds, beans, nuts, etc.). For vegetarians/vegans, it is therefore recommended to consume foods rich in zinc (cereals, herbs, yeast, dark chocolate), to avoid phytates as well as oxalates (spinach, rhubarb, artichokes). Monitoring of zinc deficiency is therefore necessary and, where appropriate, a supplement may be advised without risk given the very high toxicity threshold.

It should be noted that calcium and iron reduce its absorption. Care should therefore be exercised if taking it as a supplement.

Vitamins to be monitored

Vitamin B9

Substantial consumption of vegetables, which are rich in vitamin B9, should limit the risk of a deficiency in vegetarians/vegans. Be aware, however, of the “folate trap”, a mechanism in which a B12 deficiency may be masked as a B9 deficiency. Its specific monitoring is therefore important, especially in the context of monitoring prior to conception when it is important for the level of B9 to be correct in order to consider whether a supplement is necessary.

Vitamin B12

Lacto-ovo vegetarians will find sufficient amounts of vitamin B12 in eggs and certain cheeses (Camembert and Gouda, for example). Meanwhile for vegans, there is no source of vitamin B12 in their diet, which is only synthesised by eukaryotic organisms.

Nonetheless, it is essential in many physiological processes and this is why a supplement is essential for vegans. This supplement should be monitored via a regular vitamin B12 assay to ensure that the patient has the required amount.

A B12 deficiency can in fact cause megaloblastic anaemia, pancytopenia and severe neurological impairment likely to leave after-effects, particularly in children.

 Vitamin D

Vitamin D deficiency is pervasive in France, especially in winter, but this vitamin is essential for immunity and neuropsychic balance, among other things (in addition to its role in phosphocalcic balance). It is therefore a priority to ensure sufficient intake, but there are few foods rich in vitamin D available to vegetarians/vegans. Some cereals, or Parmesan, contain it, but in very low concentrations. Taking a supplement is therefore practically inevitable; but it must be after an assay and not blindly. As vitamin D is liposoluble, it is likely to build up in the body and an overdose can lead to toxicity.

Furthermore, a vitamin D assay makes it possible to ensure that metabolisation of calcium is correct. It is an important parameter for vegans who do not have any calcium intake from dairy products, only from plants.

Vitamin A

Sources of vitamin A are mainly animal-based foods, dairy products and eggs. Plant-based sources mainly provide carotenes (provitamin A), which can be converted to greater and lesser degrees into vitamin A. They are found in orange fruit and vegetables (carrots, mangoes, papayas) and dark green vegetables. The risk of a deficiency therefore needs to be monitored in vegans.

 

Other parameters to be monitored

Fatty acids

The elimination of fish in a vegan diet no longer allows intake of two long-chain omega-3 fatty acids essential due to their role in the brain and cardiovascular system: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid).

Plants mainly provide their precursors – short-chain fatty acids (ALA, alpha-linolenic acid) – but their conversion rate to EPA and DHA is low. A supplement is therefore very often necessary.

For good health, the recommended daily amounts are a minimum of 250 mg of DHA and EPA.

Vegetarians and vegans can find them in certain vegetable oils (camelina, rapeseed, linseed, hemp, walnut, etc.), avocados, walnuts, organic peanut butter, some types of seaweed, linseed and chia seeds. Micro-algae-based preparations are also rich in DHA (especially spirulina) or it can be administered via specific supplements.  However, it is strongly recommended to have an assay of erythrocyte fatty acids conducted in order to identify any deficiency.

Find all this information on the page dedicated to the VeggieCheck, a follow-up assessment of vegan and vegetarian diets

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