5 Nutritional Deficiencies Most Common in Vegans and How to Overcome Them

A vegan diet is a plant-based diet that comes along with many nutritious benefits as it is rich in fiber, and if following a whole-food vegan diet, it is also very rich in nutrients and low in unhealthy saturated fat. 

Vegans are less likely to develop cancer than their carnivorous friends, have lowered risk for osteoporosis, high blood pressure, heart disease, and type 2 diabetes. Furthermore, a change to this type of diet can reverse type 2 diabetes, most heart disease, and even cancer.

However, there are some health risks to watch out for, especially if you’re starting on a vegan diet without the right knowledge. Otherwise, you may risk not consuming adequate amounts of critical nutrients that are very important to your health and livelihood. These nutrient deficiencies may include:

1. Vitamin A

Vitamin A is needed for healthy skin, mucous membranes, a robust immune system, good eye health, and vision, for embryonic cells, red blood cells, and much more. Beta-carotene is the inactive precursor which is converted by the body into the active form of vitamin A, retinol. As a vegan, your primary source of Vitamin A is beta-carotene as you consume no animal products. Beta-carotene is very rich in most vegan diets as it is found in many plant foods. However, our genes play a significant role in how well we perform the conversion from beta-carotene to vitamin A.

A 2008 study shows that a difference in a single nucleotide of the DNA can control a person’s conversion rate of beta-carotene into retinol. People with a common specific genetic variation will have a decreased conversion of beta-carotene to retinol by 69%.  For other people with a less common gene variation will have a decreased conversion of beta-carotene to retinol by 32%.

This conversion also requires bile salts produced by the liver when we consume fat. You will need about six times as much beta-carotene to equal the amount of Vitamin A.

If you don’t convert beta-carotene into retinol efficiently, you may become deficient and need to supplement your diet with Vitamin A on a regular basis..

However, beware of excessive vitamin A supplementation, as vitamin A is a fat-soluble vitamin which can build up in the body over time and become toxic. Most vitamin A supplements offer 10,000 IU (international units), which is a little over the daily recommended limit for vitamin A of 3 mg per day. If, as a vegan, you suffer from severe dental carries, skin disorders or night blindness you may not be converting beta-carotene to retinol very well. I then recommend supplementing with a vitamin A 2-3 times per week, and for small vegan children who are poor converters you may wish to supplement once  or twice per week depending on their age.

To determine if you have a poor conversion rate, you may wish to do genetic testing for the SNP’s rs12934922 and rs7501331 in the BCMO1 gene.

2. Vitamin B12

Naturally occurring Vitamin B12 is synthesized by bacteria and is therefore found in areas of bacterial growth, including animal products, dirt, and soil; so some freshly picked foods may have a little of this vitamin. Some foods are fortified with vitamin B12, such as some plant milk and nutritional yeast, but for vegans, supplementation is recommended. A regular blood test can show you your levels and help determine at what rate you should be supplementing your diet. I recommend supplementing with B12 in the form of methylcobalamin. Low levels of B12 will lead to anemia, immune system disorders, weakness, fatigue, heart palpitations, shortness of breath, loss of appetite, nerve disorders including numbness, a tingling sensation, muscle weakness, problems walking, vision loss and more so it is wise to control and maintain sufficient levels of this vitamin regularly.

3. Vitamin D

Vitamin D is vital to the functioning of almost all cells of the body and is very important for bone, heart, immune and muscle cells. Vitamin D is found in animal products, fortified foods such as cereals, and some types of orange juice, and is found in mushrooms exposed to 20 minutes of sunlight or ultraviolet light. 

We can best get this vitamin from sunshine at a UV index of 3 and above (check any weather app for this information). As for Vegans who live above the longitude line of 35º, during the winter months you will not have any UVB radiation to produce vitamin D through skin exposure to the sun, and the darker your skin, the less vitamin D the body will produce from sun exposure. With no consumption of animal products, during winter months, you will most certainly be deficient in this vitamin and must take it in the form of supplementation. You can check your levels for vitamin D through a simple blood test. Levels below 40 ng/mL are considered a deficiency. 

In deficiency, I recommend about 2000 IU vitamin D per day (or if taking a 5000IU supplement, then supplement 4 times a week). When supplementing daily with Vitamin D, I recommend also taking vitamin K2 three times a week because vitamin D and K2 work together. Vitamin K2 is mainly found in specific animal foods, and fermented foods, which most people don’t eat much of, and the use of broad-spectrum antibiotics can contribute to K2 deficiency.

4. Omega-3 Fatty Acids

Omega-3s are essential fats that need to be supplied by the diet. They are necessary for strong bones, are anti-inflammatory, and care needed for proper neurological function. Rich sources of Omega-3 Fatty Acids on a plant-based diet supply alpha-linolenic acid (ALA) which is converted by the body in a few steps to the longer chain Omega 3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Food sources of ALA include walnuts, flaxseeds, hempseeds, chia seeds, and brussels sprouts; however, certain eating habits hinder the conversion of ALA into EPA and DHA.  These habits include:

High intake of Omega 6 fatty acids compared with Omega 3 fatty acid consumption (like using too much vegetable oils in your salads and cooking).

A deficiency of the nutritional co-factors involved in the conversion process which include vitamins B3, B6 (found in whole grains), vitamin C, magnesium, and zinc.

Trans-fats also destroy these conversion enzymes so a vegan diet rich in partially hydrogenated vegetable fats and processed foods including cakes, pies, cookies with frosting, donuts, margarine rich foods, microwave popcorn and so on will have too little omega 3 fats.

Also, too much alcohol will reduce the efficacy of the conversion enzymes.

This deficiency is more common in vegan males than females.

5. Iron

Iron is not as readily absorbed from plant foods as it is from animal sources. Vitamin A helps in the absorption of iron while calcium reduces iron absorption. 

Since vitamin C also helps with iron absorption and is found in many plant-based foods, I suggest consuming iron-rich plant-based foods (Soybeans and foods derived from soybeans, legumes, seeds, nuts, leafy green vegetables, and olives) along with vitamin C rich foods (broccoli, brussel sprouts, cauliflower, red peppers, spinach and other leafy greens, potatoes, tomatoes and winter squash).

This deficiency is more common in vegan females than males due to blood loss during menstruation.

You can easily maintain health on a vegan diet with proper eating habits, the right supplementation of the right nutrients you may be missing.

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Galit Goldfarb


Laird E, Ward M, McSorley E, Strain JJ, Wallace J. Vitamin D and Bone Health; Potential Mechanisms. Nutrients. 2010;2(7):693-724. doi:10.3390/nu2070693.


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