Vegan diets can have many health benefits, but they may not contain all the necessary nutrients. To avoid a deficiency, a person should be sure to consume a variety of nutritious plant-based foods and consider taking supplements.
Unless a person plans their vegan diet very carefully, they may need to take supplementary vitamin B12 and iron. A person may also need supplementary vitamin D, iodine, and omega-3 fatty acids.
Below, we look into why vegan diets may not contain all the necessary nutrients. We also describe the symptoms of specific deficiencies and which plant-based foods and supplements can help.
A well-planned vegan diet is rich in fruits and vegetables and generally low in highly refined foods.
However, any diet that does not contain whole food groups may contribute to a lack of certain nutrients. Animal products can be rich sources of certain nutrients that are more difficult to derive 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.
However, consuming fortified foods and supplements can ensure that a person with a vegan diet is receiving sufficient nutrition.
Below, we describe symptoms of common deficiencies and strategies for tackling them.
Omnivorous diets typically contain enough B12 to meet most people’s needs. As vegan diets do not include animal products, vitamin B12 deficiencies may occur.
According to the National Institutes of Health (NIH), most teenagers and adults need 2.4 micrograms (mcg) of vitamin B12 per day. This increases to 2.6 mcg or 2.8 mcg for people who are pregnant or breastfeeding, respectively.
Vitamin B12 deficiencies can cause symptoms that include:
- unexpected weight loss
- a loss of appetite
- tingling in the hands and feet
- balance problems
- difficulties remembering
- soreness of the mouth and tongue
In addition, a deficiency in vitamin B12 can cause megaloblastic anemia. This involves the bone marrow producing oversized, undeveloped red blood cells, leading to low red blood cell levels.
It can also occur from a deficiency in vitamin B9, also known as folate.
Some vegan foods are fortified with B12, but they may not provide enough. Taking a B12 or B complex supplement can help ensure a sufficient intake of this important nutrient. Anyone concerned about their B12 intake should speak with a healthcare provider.
Omega-3 fatty acids contribute to heart and brain health.
Not getting enough omega-3s can also affect the skin, causing swollen, itchy rashes or scaly, dry patches.
The three main types of omega-3 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 mainly focus 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.
As a result, it is crucial to consume sources of each omega-3. Plant-based foods that contain ALA include:
- nuts, such as walnuts
- seeds, such as chia or flaxseeds
- plant oils, such as canola oil
- fortified foods, such as cereals or juices
Focusing too heavily on ALA is also
The thyroid, a butterfly-shaped gland in the neck, converts iodine into thyroid hormones — triiodothyronine and tetraiodothyronine, known respectively as T3 and T4. These hormones help regulate crucial biological functions,
The body does not produce iodine, so a person needs to get it from their diet. The recommended daily amount for adults is 150 mcg.
Having an iodine deficiency could lead to hypothyroidism. Symptoms include:
- an inability to tolerate colder temperatures
- weight gain
- a goiter
Some vegan sources of iodine
- iodized salt
- soy milk
If a laboratory test reveals an iodine deficiency, the person needs to take an iodine supplement.
Iron is a mineral with several important functions throughout the body, including helping blood cells carry oxygen and supporting brain health.
Iron deficiencies may cause anemia, which restricts oxygen delivery to cells around the body.
Other symptoms of an iron deficiency include:
- stomach problems
- difficulty concentrating or remembering
- an increased susceptibility to infections
Heme iron is a form
The NIH report that adult males typically require around 8 mg of iron per day and adult females require around 18 mg. But as nonheme iron is harder to absorb, people with vegan diets require around twice these amounts.
Plant-based sources of iron include:
- some dried fruits, such as raisins
- iron-fortified cereals
Some people require an iron supplement, especially females of childbearing ages.
The body makes vitamin D from sun exposure. Few foods naturally contain the vitamin, but manufacturers fortify many products with it, including cereals and milk.
There are two main types of vitamin D: D2 and D3. Vitamin D3 boosts overall levels of the vitamin in the body higher and for longer than vitamin D2.
Animal products are the only natural source of vitamin D3, but vegan supplements are available. They use
A person with a vegan diet can get D2 from supplements, mushrooms, and fortified foods.
Vitamin D deficiency is very common, and a person should get their levels checked with a blood test. Depending on the results, the doctor may recommend a supplement.
Symptoms of a severe calcium deficiency include:
- numbness or tingling in the fingers
- abnormal heart rhythms
Vegan foods that contain calcium include:
- brussels sprouts
- mustard greens
- soy products
Fortified foods are also a source of calcium.
Creatine is found in animal tissues, and it helps produce energy during exercise.
Vegan diets are typically
For people with vegan diets, doctors often recommend supplements, including B12. It is a good idea to work with a knowledgeable healthcare provider, who can help develop a tailored plan to avoid nutritional deficiencies.
Having a more varied, targeted vegan diet can also account for low levels of certain nutrients. A healthcare provider can offer guidance about adapting the diet.
In general, it can also help to research nutritional contents when planning meals.
A vegan diet may not contain all the necessary nutrients, such as vitamin B12. A person can address these deficiencies by adjusting their diet and taking vegan supplements.
It is also worth noting that general nutritional information may not be tailored to people with vegan diets. For example, a person may need twice the recommended amount of iron because iron from plant-based sources is harder for the body to absorb.