For the last few decades, more and more people have become more concerned about environmental issues. Global warming, pollution, overpopulation, water crisis are now major concerns. Ethical issues have also increased within the population.
Many also choose to follow a vegan diet because they believe it is healthier from a nutritional perspective. That is not always true, as vegans often suffer from nutritional deficiencies if their diet is not well balanced. The most common deficiencies affecting vegan diets are : deficiencies in vitamin B12, vitamin D, DHA (an omega-3 fatty acid), iron and zinc.
We could encourage vegans to take supplements. But it is in fact possible to correct these deficiencies while respecting a full vegan diet.
Vegans can find vitamin B12 in enriched foods or certain types of seaweed. Many processed foods have been enriched with vitamin B12. These include enriched yeast extracts, soy products, breakfast cereals, bread, and mea-substitutes. In addition, a few plant foods naturally contain small amounts of bioactive vitamin B12. These include Nori seaweed, a type of marine algae and Tempeh, a fermented soy product.
DHA can be synthesized by the human body from the omega-3 fatty acid ALA, which is found in high amounts in flaxseeds, chia seeds and walnuts. However, the conversion of ALA into DHA is inefficient. For this reason, vegetarians and vegans often have lower amounts of DHA than meat consumers. Vegans can get this important fatty acid by taking supplements (algal oil) made from certain microalgae.
Vitamin D is not only added to cow's milk, but also to some brands of soy and rice milk and some cereals and margarines. If fortified food consumption and sunlight exposure are limited : a vitamin D supplement may be needed. It is possible to find some derived from plants.
According to the ANSES (the French national Agency dedicated to food safety), the recommended dietary allowance (RDA) for iron for vegans is 1,8 times higher than for non-vegetarians. This is because vegans generally absorb little-to-no heme iron (the animal source of iron). Some of the best plant sources are nuts, dried beans, peas, lentils, enriched cereals, whole-grain products, dark leafy green vegetables and dried fruits. It is also important to keep in mind that vitamin C can more than double non-heme iron absorption by the body. On the flip side, calcium and phytates (anti-nutrients found in grains and beans) can decrease it.
Like iron, zinc is not as easily absorbed from plant sources as it is from animal products. Plant sources of zinc include whole grains, soy products, nuts and wheat germ.
To avoid deficiencies, vegans must therefore have a very diverse diet, containing not just vegetables and fruits, but various sorts of grains, cereals, nuts, and algae as well.
Resources I have used for this report :
- https://www.anses.fr/fr (website of the French Agency of food security)
- http://www.efsa.europa.eu/fr (website of the European Agency for food secutity)
- http://www.passeportsante.net/ (French website specialized in medical and nutritional information)
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3854817/ (an interesting article from 2013 published in the Permanente Journal entitled Plant-based diets are not nutritionally deficient)