How to avoid deficiencies in a vegan diet

To avoid a deficiency, make sure to eat a variety of nutritious plant-based foods and consider taking supplements. Unless you plan your vegan diet very carefully, you may need to take vitamin B12 and iron supplements. You may also need extra vitamin D, iodine, and omega-3 fatty acids.

Here’s why vegan diets may not contain all the necessary nutrients. What are the specific deficiency symptoms and which plant foods and supplements can help.

Why Deficiencies in a Vegan Diet Occur

A well-planned vegan diet is high in fruits and vegetables and generally low in highly refined foods. However, any diet that lacks whole food groups can contribute to a lack of certain nutrients. Animal products can be rich sources of certain nutrients that are harder to get from a plant-based diet.

For example, animal products are the only natural sources of vitamin B12, which helps maintain blood cells and prevent anemia. Researchers have also found that levels of zinc, protein, selenium and other nutrients are low in vegan diets. However, consuming fortified foods and supplements can ensure that someone on a vegan diet receives sufficient nutrition.

Deficiency symptoms in a vegan diet

Vitamin B12 deficiency

Omnivorous diets generally contain enough B12 to meet most people’s needs. Since vegan diets do not include animal products, vitamin B12 deficiencies can occur. A cross-sectional analysis of participants with an omnivorous, vegetarian, or vegan diet found that about half of the 232 vegan participants had vitamin B12 deficiencies. Compared to the other groups, the vegan group had the lowest overall rates.

Most teens and adults need 2.4 micrograms (mcg) of vitamin B12 per day. This figure increases to 2.6 mcg or 2.8 mcg for people who are pregnant or breastfeeding, respectively.

Vitamin B12 deficiencies can cause symptoms such as
– tiredness
– weakness
– constipation
– unexpected weight loss
– loss of appetite
– tingling in the hands and feet
– balance problems
– difficulty remembering
– sore mouth and tongue
– confusion
– depression

Additionally, vitamin B12 deficiency can cause megaloblastic anemia. This implies that the bone marrow produces oversized and undeveloped red blood cells. This results in low red blood cell count. It can also be due to a deficiency in vitamin B9, also called folate. Some vegan foods are fortified with B12, but they may not provide enough. Taking a B12 or vitamin B complex supplement can help ensure an adequate intake of this important nutrient. Anyone concerned about their B12 intake should speak to a healthcare practitioner.

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Omega-3 deficiency

Omega-3 fatty acids contribute to heart and brain health. An omega-3 deficiency can also affect the skin, leading to swollen, itchy rashes or scaly, dry patches. The three main types of omega-3s are alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA).

The body can convert ALA to DHA and EPA in very small amounts. For this reason, some people focus primarily on consuming ALA. However, the conversion rate is very low: Only 5-8% of ALA is converted into EPA and a maximum of 5% is converted into DHA. Therefore, it is crucial to consume sources of each omega-3.
Plant-based foods that contain ALA include:

– nuts,
– seeds, such as chia or flax seeds
– vegetable oils, such as rapeseed oil
– fortified foods, such as cereals or juices

Focusing too heavily on ALA is also risky because if a person consumes too much linoleic acid, a type of fat concentrated in foods including soybean oils and nuts and seeds, it further impairs the conversion of ALA. ALA to DHA and EPA. Seaweed is a vegan source of DHA and EPA. It is currently unknown how much DHA and EPA is needed for a healthy diet.

Iodine deficiency

The thyroid, a butterfly-shaped gland located in the neck, converts iodine into thyroid hormones – triiodothyronine and tetraiodothyronine, known as T3 and T4 respectively. These hormones help regulate crucial biological functions, such as metabolism. The body does not produce iodine, which is why a person needs to get it from their diet. The recommended daily amount for adults is 150 mcg.
Iodine deficiency can lead to hypothyroidism.

Symptoms of iodine deficiency:

– an inability to tolerate colder temperatures
– fatigue
– weight gain
– a goiter

Some vegan sources of iodine are included:
– iodized salt
– soy milk
– seaweed
– cranberries
– potatoes
– prunes
If a lab test reveals an iodine deficiency, the person should take an iodine supplement.

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Iron deficiency

Iron is a mineral that performs several important functions in the body. Including helping blood cells carry oxygen and supporting brain health.
Iron deficiencies can cause anemia, which restricts the supply of oxygen to cells in the body.

Other symptoms of iron deficiency are:

– stomach problems
– fatigue
– weakness
– difficulty concentrating or remembering
– increased susceptibility to infections

Heme iron is a common form in meats, fish and eggs. The body absorbs it easily. Herbal products contain non-heme iron, which is harder to absorb.

Adult men need about 8 mg of iron per day and adult women about 18 mg. But since non-heme iron is more difficult to absorb, people on a vegan diet need about twice that amount.

Plant-based sources of iron include:
– nuts
– certain dried fruits, such as raisins
– beans
– lentils
– spinach
– peas
– cereals fortified with iron

Some people need an iron supplement, especially women of childbearing age.

Vitamin D3 deficiency

Vitamin D helps absorb calcium for healthy bones and protects against chronic bone diseases, such as osteoporosis. The body makes vitamin D from exposure to the sun. Few foods naturally contain this vitamin, but manufacturers fortify many products with this vitamin, including cereals and milk. There are two main types of vitamin D: D2 and D3. Vitamin D3 increases overall vitamin levels in the body more strongly and longer than vitamin D2.

Animal products are the only natural source of vitamin D3, but there are vegan supplements. They use lichen as a source. A person on a vegan diet can get D2 from supplements, mushrooms, and fortified foods. Vitamin D deficiency is very common. You should have your level checked with a blood test. Depending on the results, the doctor may recommend a supplement.

Calcium deficiency

Calcium is an important mineral for bone health and muscle function. A deficiency could increase the risk of problems such as osteoporosis or bone fractures.

Symptoms of severe calcium deficiency include:

– numbness or tingling in the fingers
– abnormal heart rhythms
– seizures

Some vegan foods that contain calcium include:

– broccoli
– Brussels sprouts
– kale
– mustard leaves
– Swiss chard
– beans
– peas
– soy products

Fortified foods are also a source of calcium.

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Creatine deficiency

Creatine is found in animal tissues, and it helps produce energy during exercise. Vegan diets are generally lower in creatine than other diets. Although creatine is not an essential nutrient, it can improve athletic performance. Taking a synthetic, and therefore vegan, creatine supplement can compensate for the decrease in creatine stores in the muscles.

Rebalancing deficiencies in a vegan diet

For people on a vegan diet, doctors often recommend supplements, including B12. It’s good to work with a knowledgeable healthcare provider, who can help develop a tailored plan to avoid nutritional deficiencies. A more varied and better targeted vegan diet may also explain the low levels of certain nutrients.

A vegan diet may not contain all necessary nutrients, such as vitamin B12. These deficiencies can be remedied by adapting your diet and taking vegan food supplements. It should also be noted that the general nutritional information may not be suitable for people on a vegan diet. For example, a person may need twice the recommended amount of iron because iron from plant sources is harder for the body to absorb.


Anemia, megaloblastic. (2008).

Calcium. (2019).

Fallon, N., et al. (2020). Low intakes of iodine and selenium amongst vegan and vegetarian women highlight a potential nutritional vulnerability.

Ferreira, A., et al. (2019). Multilevel impacts of iron in the brain: The cross talk between neurophysiological mechanisms, cognition, and social behavior.

Gilsing, AM, et al. (2010). Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians and vegans: Results from a cross-sectional analysis of the EPIC-Oxford cohort study.

Iodine. (2020).

Iron. (2019)

Kaviani, M., et al. (2020). Benefits of creatine supplementation for vegetarians compared to omnivorous athletes: A systematic review.

Orlich, MJ, et al. (2013). Vegetarian dietary patterns and mortality in Adventist Health Study 2.

Peltomaa, E., et al. (2018). Marine cryptophytes are great sources of EPA and DHA.

* Presse Santé strives to transmit medical knowledge in a language accessible to all. In NO CASE can the information given replace medical advice. []

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