Is the vegan diet a malnutrition?
People who want to nourish themselves with plants only or already do, are often confronted with prejudices. The following questions are asked often:
"Where do you get your protein from?"
"Can you even cover your needs of B12, calcium and iron?"
"You look pale! That definitely comes from a nutrient deficiency."
In general: without any animal products, there can only be a deficiency. but that is not true. With a well balanced vegan diet, deficiency symptoms are very implausibly. If the nutrition is too one-sided, deficiency symptoms are possible.
The following nutrients are regarded as critical in connection to the vegan diet. If this is really true, our research will show. Generally, deficiency symptoms can occur in all forms of diet.
Proteins / Amino Acids - No Deficiency
Studies showed, that in comparison with other forms of diets, the vegan diet has the lowest levels of protein (in average 82 g a day, 14 % of the total calory intake) 1. If the daily need of protein of 0.8 g per kg body weight is taken as the bases of the studies, the result is not that bad.
Athletes as well as people who have a straining job, have a higher need of protein (about 1.2 to 1.6 g / kg). This group of people should have an eye on a nutrition rich in protein, because the amino acids are essential for the cell construction (for instance muscle buildup) and the regeneration of the cells. Vegans can handle the vegan diet excellently without any nutrition supplies.
Supplying the body with all amino acids (essential and non-essential) by eating vegan is not problematic, because all amino acids are contained in sufficient amounts in plant foods. Essential amino acids cannot be built from the body itself and have to be supplied by the nutrition.
Nonetheless the values of the amino acids partly vary considerably. To cover all of the amino acid needs in adequate amounts it is necessary to eat variedly. The different amino acids can be applied from many various plant sources 2. That includes the consumption of grains (e.g. oat flakes), legumes (beans, lentils and peas) as well as nuts and seeds - see list of foods rich in protein.
Vitamin B12 - Very Critical
Vitamin B12 amongst other things is needed for blood formation, cell buildup and cell division. Additionally, it keeps the homocysteine level low. Cardiovascular diseases are related with a too high homocysteine level. The body can save vitamin B12 up to 3 years. Therefore, deficiency symptoms can appear after years at first. If a vitamin B12 deficiency is not eliminated, it can lead to irreversible nerve damages 3.
Because usable vitamin B12 only is contained in a few vegan non-processed foods, such as mushrooms and some seaweeds like chlorella and nori, the daily need of B12 (2.4 µg / day) can only badly be covered by a fresh and plant diet. This causes a deficiency of B12 with many vegans 4 5 6.
That is why cyanocobalamin, a form of vitamin B12 often is added to processed foods like plant based drinks and soy yoghurt. The named products make it easier to cover the need. Yeast, beer and sauerkraut do not contain B12. These are analoga, which structurally are similar to the B12, but they are not biologically active and cannot be utilized.
Vitamin B2 (Riboflavin) - Potentially Critical
A deficiency of riboflavin can also appear when being vegan, because according to studies, the amounts of the daily intake are below the daily need 7 8. Besides an insufficient supply with foods that contain vitamin B2 (list), the wrong storage of fruits and vegetables can be a cause for a deficiency. Vitamin B2 is light-sensitive and will be destroyed by sunlight 9.
Riboflavin is needed to convert proteins, carbohydrates and fats into energy. Almonds, lentils, quinoa, white mushrooms, buckwheat and grain products like oat flakes are good sources of vitamin B2.
Vitamin K2 (Menaquinone) - Potentially Critical
An adequate supply of vitamin K2 can be a challenge for vegans, as plant-based foods mainly contain vitamin K1 10. Vitamin K2 is only present in very few vegan foods. Although the body can convert vitamin K1 to vitamin K2, it can only do so to a limited extent. This mainly occurs in the liver and is controlled by enzymes. About 10 % of the required vitamin K2 can be converted from vitamin K1. Therefore, it is important to consume foods with sufficient vitamin K1.
However, it should be noted that not all forms of vitamin K2 can be formed from vitamin K1. There are several types of vitamin K2, such as MK-4 and MK-7, which differ in their structure and biological activity. In addition, the bioavailability of vitamin K1 is lower compared to vitamin K2. Vitamin K2 is therefore better absorbed and utilized by the body than vitamin K1.
Vitamin D - Critical In The Winter Months
Especially in the winter months vegan have a bigger risk of getting a lack of vitamin D, because there are only a few plant foods containing vitamin D 11 12. Therefore is is often added to plant-based drinks. Vitamin D is needed for the absorption of calcium and phosphorus, which are important for teeth and bones.
To fill the reservoir of vitamin D it is useful to sun yourself, according to your skin type, without sunscreen (it blocks the UVB radiation) in the summer months. Under the impact of sunlight on the skin, the human body is able to build a high amount of vitamin D. The reserves from the summer are used to cover the need in the times of no UVB radiation. But the reserves mostly are not enough to cover the entire need throughout the whole winter.
Iron - Unproblematic
Iron mainly is needed for the blood formation process and makes the blood's transport of oxygen and carbon dioxide possible. Compared to other forms of diets, the daily iron intake of vegans is the highest with 23 mg and 19.9 mg 13 14. Results of Danish studies in 2015 prove higher iron values at vegans in comparison with the general population 15. An iron deficiency can also occur at humans, who eat plants only 16. Especially women should have an eye on iron, because of the monthly bleeding 17. Supplying the body with enough iron is easy with a well-balanced diet. A simple trick is also very helpful.
Phytates and oxalic acid (anti nutrients), which are contained in seeds, dark green vegetables and nuts in higher amounts, inhibit the absorption of iron from the nutrition. To absorb the iron better, vitamin C and citric acid are useful 18. If possible, you should consume foods containing iron (list) together with foods rich in vitamin C.
You can find higher amounts of iron in (pseudo) grains like quinoa and legumes. Spinach, that is often advertised as a good iron source only has a small percentage of iron compared to the two food groups named above. Additionally, the spinach's iron absorption is impeded by the high percentage of oxalic acid.
Zinc - Rather Unproblematic
The human body needs the essential trace element zinc for numerous metabolic processes. Additionally, it influences growth hormones and insulin. There can be a deficiency of zinc when you eat vegan 19. In a small Swiss study vegans had the highest prevalence for a zinc deficiency (47%) 20.
Concerning anti nutrients, it is similar to the case of iron. Have an eye on the fact that phytic acid and calcium can bond to zinc, which makes the absorption rate from the nutrition smaller. By eating legumes, peanuts and whole grain products, it is easy to cover the daily need of 8 to 11 mg a day (value for adults). Here you can find the foods containing zinc.
Iodine - critical
According to studies, vegans often have a deficiency of iodine 21. It is an essential trace element and is needed for the synthesis of the thyroid hormones. Effects of a deficiency can be swallowing and breathing difficulties as well as a swelling of the thyroid.
To cover the daily need of iodine, it is recommended to consume sea weeds that contain iodine. They are very rich in iodine. Therefore, they generally should be used sparingly. If possible, avoid iodized table salt, because it often is just recycled industrial garbage.
Calcium - Rather Unproblematic
Good sources of calcium are seeds like sesame and stone fruits like almonds. Green vegetables like kale, swiss chard and broccoli also contain much calcium. Often it is added to plant based drinks. You can find more calcium containing foods in the list.
Selenium - Potentially Critical
Selenium belongs to the essential trace elements. It plays an important role concerning the immune system and protection from free radicals. Vegans can be affected by a selenium deficiency, therefore, it is necessary to know, which foods contain selenium 25 26.
Brazil nuts are full of selenium. You can cover the daily need with two of them already. lower amounts can be found in seeds and nuts as well as in whole grain products.
Omega-3 Fatty Acids - Rather Not Problematic
Nevertheless, there are enough plant foods with omega-3 fatty acids like linseeds (linseed oil), chia-seeds and hemp seeds, which contain higher amounts of omega-3. They make it easy to cover the daily need.
When having a bad relation between omega-3 and omega-6 fatty acids, health problems can occur. If there is an imbalance, cardiovascular problems and obesity can be results 30. The major part of the fatty acids is omega-6, and that causes the imbalance. Inevitable, vegans have a higher intake of omega-6. Therefore, have an eye on consuming foods with more omega-3 instead. Ideally, the relation is balanced by 1:1. According tot his, you especially better avoid sunflower oil, soy oil and safflower oil. Alternatively you can use rapeseed oil.
A nutrition deficiency can occur by healthy people, ignoring the vitamin B12 problem, only if you eat very unbalanced. Concerning B12, it is advisable to consume enough foods enriched with B12 and mushrooms in regular intervals. Eat consciously and keep in mind the essential nutrients, this prevents deficiencies. The nutrition should be as varied as possible, preferred with a high part of omega-3 fatty acids.
Plants offer a huge range of various foods to design the diet versatile. If you consume many processed foods, there can be a deficiency of nutrients. But if you keep an eye on eating many fresh foods, the intake of nutrients is higher and the body can use the health advantages of the vegan diet optimally.