Vegan Diets: Nutritional Deficits And How To Address Them

Vegan diets are often promoted as being good for heart health. However, eliminating animal products may cause nutritional deficiencies and could lead to negative consequences.

A comprehensive review published in the medical journal Progress in Cardiovascular Diseases found that a vegan diet may lead to nutritional deficiencies in vitamin B12, omega-3, calcium, zinc, iron, magnesium, and high-quality protein. These deficiencies may be associated with an increased risk of certain types of cancer, stroke, bone fractures, preterm birth, and failure to thrive.

Vitamin B12 is an essential nutrient that is almost exclusively found in animal-sourced foods, such as fish, meat, dairy products, and eggs. Vegans who don't take supplements are at a higher risk of vitamin B12 deficiency than vegetarians.

Vitamin D3 (cholecalciferol) is another nutrient that may be lacking in a vegan diet. Cholecalciferol is found in animal-based foods, especially fatty fish. Vegans can get this important nutrient by taking supplements made from lichen.

Docosahexaenoic acid (DHA), an essential omega-3 fatty acid, is mainly found in fatty fish and fish oil. Vegans can get DHA by taking supplements in the form of algal oil, which is made from certain microalgae.

Heme iron is a type of iron found only in meat, especially red meat. Non-heme iron is found in plant foods but is poorly absorbed. Vegans and vegetarians are more prone to anemia than meat-eaters due to the lower bioavailability of iron from plant-based diets.

Creatine is a molecule found in animal foods that plays an important role in brain and muscle function. Vegans can get creatine by taking synthetic supplements.

Overall, a well-planned vegan diet can be healthy, but it may require careful consideration to ensure adequate intake of certain nutrients.

Vitamin B12

Vegans can supplement their diet with vitamin B12 by consuming fortified foods such as enriched yeast extracts, nori seaweed, tempeh, and vegan-friendly supplements.

Omega-3

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, but in very small amounts. For this reason, it is crucial to consume sources of each omega-3.

ALA is found in plant-based foods such as:

• Nuts, such as walnuts
• Seeds, such as chia or flaxseeds
• Plant oils, such as canola oil
• Fortified foods, such as cereals or juices

DHA and EPA are mainly found in animal products, but vegans can get these omega-3s from microalgae supplements and DHA-fortified foods. DHA is also present in certain types of microalgae, which are suitable dietary sources for vegans and vegetarians.

It is currently unclear how much DHA and EPA are necessary for a healthy diet.

Calcium

Symptoms of a severe calcium deficiency include:

• Numbness or tingling in the fingers
• Muscle cramps
• Abnormal heart rhythms

Vegan foods that contain calcium include:

• Dark, leafy greens (e.g. kale, spinach, collards, turnip greens, mustard greens)
• Tofu
• Tahini
• Fortified foods (e.g. cereals, soy, rice, almond and coconut beverages, orange and apple juices)

Iron

Plant-based sources of iron include:

• Beans
• Lentils
• Tofu
• Quinoa
• Tempeh
• Some dried fruits, such as raisins
• Iron-fortified cereals
• Spinach
• Peas
• Cashews
• Pumpkin seeds
• Whole grains

Vitamin D

There are two types of dietary vitamin D: ergocalciferol (D2), found in plants, and cholecalciferol (D3), found in animal-based foods. Cholecalciferol (D3) increases blood levels of absorbable vitamin D much more efficiently than ergocalciferol (D2). The best sources of vitamin D3 are fatty fish and egg yolks. Other sources include supplements, cod liver oil, or enriched foods like milk or cereals.

Since the main dietary sources of vitamin D3 are not plant-based, vegetarians and vegans may be at a higher risk of deficiency, especially during the winter in countries far from the equator. Deficiency in vitamin D is linked to an increased risk of various adverse health conditions, including osteoporosis, multiple sclerosis, impaired brain function, and muscle wasting and reduced strength, especially in older adults.

Vegan vitamin D3 supplements made from lichen are also available.

Frequently asked questions