Vegan diets contain nutrients that require special attention. Vitamin B12 and D and iodine are the most common deficiencies, so careful consideration must be given to where the body gets them from. Vegans also need to pay attention to eating enough calcium, selenium, omega-3 fatty acids and vitamin A. Protein (including all essential amino acids), vitamin B2, iron and zinc can all be provided if a balanced menu is planned (different foods from all plant food groups), as well as the other principles of plant nutrition mentioned above.
Food supplements and foods fortified with vitamin B12 are sources of vitamin B12 for vegans. No non-enriched foods of non-animal origin contain vitamin B12 in a digestible form for the body. Examples of foods fortified with vitamin B12 are appropriate plant-based beverages and yeast flakes.
Vitamin D can be produced to some extent by the human body when exposed to sunlight. In our latitudes, this can only be counted on during the summer months; otherwise, dietary supplements are by far the best sources. Although vitamin D is added to fortified vegetable beverages, for example, the amounts it contains are insufficient to meet the need. Since vitamin D is a fat-soluble vitamin, drinking only vitamin D-enriched water (and other drinks with no or minimal fatty acids) does not help to replenish the body.
On this basis, it is recommended to take vitamin D oil as a dietary supplement year-round.
For vegans, vitamin D3 produced from lichen is suitable, as is vitamin D2.
Vegans have three good sources of iodine: seaweed, iodized salt, and iodine-containing supplements. If none of these three are part of the daily diet, vegans’ iodine intake may be inadequate and will probably be only one-third to one-half of the recommended amount.
The amount in algae can vary greatly from species to species, as well as within a particular species, so one should know the iodine content of a particular product to avoid both over- and under-consumption. Because of the high variability in iodine content, it is not advisable to rely solely on algae for iodine.
For much of the world’s population, the problem of getting enough iodine has been solved by using iodized salt, and in many countries, salt iodization is mandatory. If salt is to be added, the iodized version should be preferred. However, since people usually consume too much salt, this may not be the best way to meet the need for iodine. Thus, iodine supplements are the most convenient and easy solution for vegans because they contain a certain amount of iodine and thus prevent excessive salt intake.
When getting iron, all groups of plant-based foods work together as a whole. Legumes, nuts, seeds and grains are good sources of iron, and fruits and vegetables rich in vitamin C help better absorb non-heme iron if eaten in the same meal as iron-rich foods. People at risk for iron deficiency are advised to avoid tea, coffee, and cocoa with their meals because the compounds they contain interfere with iron absorption. You should also consider that iron in plant-based foods is less digestible, and therefore the iron requirement may be slightly higher than for omnivores. The best sources of plant-based iron are seeds, legumes, raisins, bread, whole grain products, buckwheat and strawberries.
Calcium is found in almost all plant foods, although mostly in small amounts. Vegans can meet their calcium needs by eating calcium-rich plants. Although the calcium content may be significant in the case of some plants, be aware that they may contain compounds that make it difficult to absorb calcium. Consumption of fortified plant-based drinks and tofu enriched with calcium salts makes it easier to get enough calcium. Vitamin D promotes calcium absorption.
Most green leafy vegetables, broccoli, almonds and other nuts, tahini, sesame and chia seeds, figs, oranges, tangerines, white garden beans, soybeans, chickpeas, for example, contain calcium.
The selenium content of foods depends on the growing soil. Because soils in Northern Europe are quite poor in selenium, it is recommended that local vegans eat several Brazil nuts a day to provide the necessary amount. Sunflower seeds are also a good source of selenium.
The best sources of zinc are those parts of the plant from which new life begins, such as legumes, nuts, seeds, and grains. Plants have compounds that impair the body’s absorption of zinc, so the recommended amount of zinc intake for vegans is slightly higher (25-30%) compared to the recommendations for an omnivorous diet.
Essential fatty acids
Alpha-linolenic acid (ALA) is an essential omega-3 fatty acid found in plant foods. About one tablespoon of ground flaxseed or whole chia or hemp seeds, a handful of walnuts, or 2 to 3 tablespoons of rapeseed oil added during cooking covers the daily requirement of ALA. The human body uses ALA to produce long-chain omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The efficiency with which ALA is converted to long-chain fatty acids (EPA and DHA) depends on gender, age, and individual differences, as well as on diet. Low energy levels in the diet, lack of protein, vitamin B6, biotin, calcium, copper, magnesium, or zinc, and high levels of linoleic acid (LA, omega-6 fatty acids) and trans fats in the diet impair EPA and DHA synthesis. Since vegetarian menus may contain high amounts of LA (from nuts, seeds, grains, and vegetable oils), to achieve an optimal ratio of omega fatty acids and promote the conversion of ALA into long-chain omega-3 fatty acids, Limit consumption of omega-6 fatty acid-rich oils (sunflower, corn, soy, safflower oils), tropical oils high in saturated fatty acids (coconut, palm and palm kernel oils) and trans fats. DHA is an important component of nerve cells and retinal membranes, so consuming the right amount of DHA is especially important during pregnancy and lactation, as well as for brain health in old age, so vegans are recommended to consume 250 mg of microalgae oil rich in DHA 2-3 times a week.
All sources of vitamin A are of animal origin, but plant foods contain beta-carotene, a precursor substance to vitamin A, and the body converts beta-carotene to vitamin A. The most concentrated sources of beta-carotene are carrots and yams, as well as dark green leafy vegetables such as cabbage and all kinds of green, red, dark yellow fruits and vegetables. If these are not on the menu on a regular basis, you may not be getting enough vitamin A. Also consider that the body needs fats to absorb beta-carotene.
Protein, including essential amino acids
Protein content in plant foods is usually lower than in animal foods. In addition, the digestibility of plant proteins is lower than that of animal proteins due to some compounds contained in plants. It is therefore especially important to pay attention to an adequate protein intake during periods of high protein requirement (pregnancy, breastfeeding). It is advisable to vary different plant protein sources to ensure that you get enough of the different essential amino acids. The richest protein sources for vegetarians, including essential amino acids, are legumes (beans, peas, lentils, soybeans), nuts and seeds, cereals, buckwheat and quinoa. With a balanced and varied diet, getting enough protein and all essential amino acids will not be a problem for vegans.
A balanced and varied plant-based diet usually contains enough vitamin B2. The best sources of most B vitamins are yeast flakes; sources of vitamin B2 include mushrooms, almonds, cashews, green leafy vegetables, broccoli and fortified plant-based drinks.
Vegetarian menus that are based on natural, high-fiber foods such as whole grains, fruits and vegetables (including legumes), berries and nuts usually contain plenty of fiber. However, the high amount of fiber found in plant-based foods and some other substances can interfere with the absorption of proteins and/or impair the absorption of some minerals.