What is Vitamin D?
Publications and information about vitamin D intake always pop up at the end of summer. But it may be too late by then to store up on the "sunshine vitamin" as Autumn is already setting in.
Also, vitamin D is misnamed, actually, as it is not a vitamin as it can be manufactured by the skin. It is in fact a pro-hormone, meaning that it acts as a hormone precursor.
Why is Vitamin D so important?
Vitamin D is the "central governor” controlling ossification. It works in synergy with calcium and phosphorus helping them enter the bloodstream and making them available for cell and bone function. At the end of the process, the same vitamin D regulates the proper elimination of calcium and phosphorus.
The functions of vitamin D go far beyond bone health and osteoporosis prevention.
Recent research points to the link between vitamin D deficiency and many diseases such as type 1 and 2 diabetes, immune deficiencies (susceptibility to infections and viruses), respiratory issues (asthma), muscular problems, polyarthritis, and gut inflammatory syndromes such as Crohn disease.
Studies point to an increasing deficiency in vitamin D throughout Europe. Whereas the change in nutritional and life habits seems to be one of the main reasons for this, the issue would appear to affect the whole population, whether young, elderly, vegan, or non-vegan.
How do we produce vitamin D?
Vitamin D is produced from a synergic reaction between UV radiation and a cholesterol compound obtained from food sources.
This particularly concerns vegans as a vegan diet might be lacking both vitamin D itself and the other food precursors. as the process cannot occur without there being proper amounts of cholesterol derived from animal sources. It is unusual indeed to praise cholesterol but yes, you may thank your cholesterol levels and make sure you have enough to sustain your vitamin D production!
Why is vitamin D a special concern for vegans?
It is important to make the distinction between vitamin D2 and vitamin D3.
Vitamin D2 (ergocalciferol) is, on average, plant-based while vitamin D3 (cholecalciferol) comes, not exclusively but normally, from animal sources such as salmon, sardines, cod liver, and so forth. It is thanks to the fatty acids from these sources that vitamin D is produced. When talking about vitamin D deficiency, it is usually the D3 type (or 1,25 dihydroxyvitamin D) that is referred to. This is why vegans must pay special attention to their vitamin D3 intake.
Consuming sufficient vegan sources of vitamin D3 as well as supplementing with vegan vitamin D is part of the job if you are a health-conscious vegan.
Vitamin D foods for vegans
As mentioned above, most plant-based sources of vitamin D are the vitamin D2 type. Here is a list of fruit and vegetables containing vitamin D2:
- mushrooms (white, portobello, shitake)
Do keep in mind that vitamin D2 is more difficult to metabolize than the D3 form. This is why you have to make sure you are getting sufficient vitamin D3.
Luckily for vegans and non–vegans, research is advancing and more and more plant-based sources of vitamin D3 are on the verge of being commercialized.
Supplementing becomes necessary as nature does not provide sufficient plant-based sources of vitamin D3.
Best vegan vitamin D supplements
The most common vegetable source of D3 vitamin comes from lichen (lichen boréal Cladonia rangiferina) which grows in northern countries such as Scandinavia, North America and Canada.
Lichen stocks vitamin D3 as it grows due to the synergy symbiosis between a moss and a mushroom. As the vitamin content lessens after harvesting, lichen oil is extracted and processed on the spot. The lichen source of vitamin D3 is completely vegan and as efficient as its animal source counterparts.
The good news is that as research advances and new environmental-friendly extraction processes appear, the cost of lichen-based D3 will lessen.
If fish metabolize their vitamin D3 because they feed on microalgae, could the same algae provide us with a source of vegan vitamin D3?
Scientists have managed to extract vitamin D3 from a form of red algae. As with lichen, the vitamin D3 is extracted using alcohol and enzymes. Results are encouraging as it is easy to grow algae in an environmentally friendly manner.
"Vitashine" has the patent for both lichen and algae vitamin D3 sources. They offer plant-sourced vitamin D3 supplements produced with zero pesticides or other harmful solvents.
3) Tomato leaf
As research continues, the tomato leaf seems to be the next available plant-based source of vitamin D3. A patent has been registered but no supplement is available on the market yet.
Vitamin D3 needs
The EFSA (European Food Safety Authority) has determined daily security intakes between 400 and 2000 ui. These amounts vary according to individual cases and any supplementation must be conducted under the advice of a medical practitioner. The safest and wisest step to take is to have a blood test done and decide on the supplementation protocol with your healthcare practitioner.
Author: Marie-Noëlle Bourgeois, Nutritionist at Bounce Up Micronutrition
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Sources and Further Reading:
Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.
Statut en vitamine D de la population adulte en France : l'Etude nationale nutrition santé (ENNS, 2006-2007), Vernay M, Sponga M, Salanave B, Oleko A, Deschamps V, Malon A, Castetbon K
Bulletin Epidémiologique Hebdomadaire, 2012, n°. 16-17, p. 189-94
Lips, P., Cashman, K., Lamberg-Allardt, C., Bischoff-Ferrari, H., Obermayer-Pietsch, B., Bianchi, M., Stepan, J., El-Hajj Fuleihan, G., & Bouillon, R. (2019). Current vitamin D status in European and Middle East countries and strategies to prevent vitamin D deficiency: a position statement of the European Calcified Tissue Society, European Journal of Endocrinology, 180(4), P23-P54. Retrieved Feb 15, 2021, from https://eje.bioscientifica.com/view/journals/eje/180/4/EJE-18-0736.xml