How to avoid the deficiencies of a vegetarian diet

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

Here’s why plant-based diets don’t contain all the necessary nutrients. What specific deficiency symptoms and foods and botanical supplements can help.

Why do deficiencies occur in a vegetarian diet

A well-planned vegetarian diet is rich in fruits and vegetables and generally low in highly refined foods. However, any diet that lacks whole food groups can contribute to a deficiency of certain nutrients. Animal products can be rich sources of some nutrients that are difficult to obtain from a vegetarian diet.

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

Symptoms of deficiency in a vegetarian diet

Vitamin B12 deficiency

Omnivorous diets generally contain enough vitamin B12 to meet the needs of most people. Because a vegetarian diet does not include animal products, vitamin B12 deficiency can occur. A cross-sectional analysis of participants following a vegetarian or vegan diet found that about half of 232 vegetarian participants had a vitamin B12 deficiency. Compared with the other groups, the group had Vegetarian lowest overall rates.

Most teens and adults need 2.4 micrograms of vitamin B12 daily. This number increases to 2.6 mcg or 2.8 mcg for people who are pregnant or breastfeeding, respectively.

Vitamin B12 deficiency can cause symptoms such as
– Tired
– weakness
– Constipation
Unexpected weight loss
– Anorexia
Tingling in the hands and feet
Balance problems
Difficulty remembering
– Inflammation of the mouth and tongue
– confusion
– depression

In addition, vitamin B12 deficiency can cause megaloblastic anemia. This means that the bone marrow produces large, incompletely developed red blood cells. This results in a low red blood cell count. It could also be due to a deficiency of vitamin B9, also known as folate. Some plant foods are fortified with vitamin B12, but they may not provide enough. Taking a vitamin B12 or B-complex vitamin supplement can help ensure an adequate intake of this important nutrient. Anyone concerned about their B12 intake should speak to a healthcare practitioner.

Omega 3 deficiency

Omega-3 fatty acids contribute to heart and brain health. Omega-3 deficiency can also affect the skin, resulting in 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 into 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 to EPA and a maximum of 5% is converted to DHA. Therefore, it is essential to eat sources of all omega-3s.
Plant foods that contain ALA include:

– nuts,
Seeds, such as chia or flaxseeds
Vegetable oils such as rapeseed oil
Fortified foods such as cereal or juice

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

iodine deficiency

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

Symptoms of iodine deficiency:

Inability to tolerate cold temperatures
– Tired
– overweight
– Goiter

Some plant sources of iodine are included:
– iodized salt
– Soy milk
– seaweed
– Cranberries
– Potatos
– plum
If a lab test shows iodine deficiency, the person should take an iodine supplement.

Iron deficiency

Iron is a mineral that performs many important functions in the body. Including helping blood cells carry oxygen and supporting brain health.
Iron deficiency can cause anemia, which limits the supply of oxygen to the body’s cells.

Other symptoms of iron deficiency are:

Stomach problems
– Tired
– weakness
Difficulty concentrating or remembering
Increased susceptibility to infection

Heme iron is a common form in meat, fish, and eggs. It is easily absorbed by the body. Herbal products contain non-heme iron, which is difficult to absorb.

Adult men need about 8 mg of iron per day, and adult women need about 18 mg. But because non-heme iron is more difficult to absorb, people who follow a vegan diet need about twice as much.

Plant sources of iron include:
– nuts
Some dried fruits, such as raisins
– beans
– lentil
– spinach
– peas
Iron-fortified cereal

Some people need iron supplements, especially women of childbearing age.

Vitamin D3 deficiency

Vitamin D helps with calcium absorption for healthy bones and prevention of chronic bone diseases, such as osteoporosis. The body makes vitamin D from exposure to sunlight. Few foods naturally contain this vitamin, but manufacturers enhance many products with this vitamin, including cereal and milk. There are two main types of vitamin D: D2 and D3. Vitamin D3 increases total vitamin levels in the body more powerfully and for a longer period of time than Vitamin D2.

Animal products are the only natural source of vitamin D3, but there are plant-based supplements. They use lichen as a source. Anyone following a vegan diet can get D2 from supplements, mushrooms, and fortified foods. Vitamin D deficiency is very common. Your level should be checked with a blood test. Depending on the results, your doctor may recommend supplementation.

lack of calcium

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

Symptoms of severe calcium deficiency include:

Numbness or tingling in the fingers
– Arrhythmia
– seizures

Some plant foods that contain calcium include:

– Broccoli
– cabbage
– cabbage
– mustard leaves
– chard
– beans
– peas
– soy products

Fortified foods are also a source of calcium.

Creatine deficiency

Found in animal tissues, creatine helps produce energy during exercise. Plant-based diets generally contain less creatine than other diets. Although creatine is not an essential nutrient, it can improve athletic performance. Taking synthetic, and therefore plant-based, creatine supplements can make up for the shortfall in muscle creatine stores.

Rebalancing the deficiencies of a vegetarian diet

For people who follow a plant-based diet, doctors often recommend supplements, including B12. It’s a good idea to work with a knowledgeable healthcare provider, who can help create a customized plan to avoid nutritional deficiencies. A more diverse, better-targeted plant-based diet may explain the lower levels of some nutrients.

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


Megaloblastic anemia. (2008).

Calcium. (2019).

Fallon, N, et al. (2020). Low iodine and selenium intake among vegetarian and vegan women highlights potential nutritional weaknesses.

Ferreira, A, et al. (2019). The multilevel effects of iron in the brain: crosstalk between neurophysiological mechanisms, cognition, and social behavior.

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

iodine. (2020).

iron. (2019)

Cavani, M, et al. (2020). Benefits of creatine supplementation for vegetarians compared to craving athletes: a systematic review.

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

Biltuma, E., et al. (2018). Marine crypt cells are great sources of EPA and DHA.

* Presse Santé strives to impart medical knowledge in a language accessible to all. In no way can the information provided replace medical advice.

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