There is a growing trend among Canadians to eat a plant-based diet. In 2020, approximately 850,000 Canadians identified themselves as vegan, and an additional 2.3 million Canadians identified themselves as vegetarian.^[i] Plant-based eating has been widely celebrated for its numerous health benefits, including reduced risks of heart disease, type 2 diabetes, and some cancers.^[ii] Veganism has gained a strong following as people seek more ethical and environmentally sustainable ways of eating. However, as with any diet, a vegan or exclusively plant-based lifestyle requires careful planning to ensure balanced nutrition. Without proper attention, certain nutrient deficiencies may arise, potentially leading to health issues over time. In this article, we’ll explore some of the most common nutrient deficiencies among vegans.

Common Nutrient Deficiencies in a Vegan Diet

Iron Deficiency

Iron is essential for oxygen transport, energy production, and immune function. While plant-based foods like lentils, spinach, and quinoa provide iron, it’s in the nonheme form, which the body absorbs less efficiently than the heme iron found in animal products. The difference in bioavailability is stark, with 25–30% of heme iron being absorbed as compared to 1–10% absorption for nonheme iron.[iii] Iron deficiency is common among vegans, with studies showing that vegans have lower serum ferritin (the storage form of iron) levels compared to omnivores.[iv]

Vitamin B12 Deficiency

Vitamin B₁₂, also known as cobalamin, is one of the most critical nutrients that vegans must monitor. It plays a vital role in red blood–cell production, neurological function, and DNA synthesis. Deficiency in B₁₂ can lead to anaemia, neurological disorders like tingling or numbness in the extremities, and cognitive impairments. The primary sources of B₁₂ are animal-based foods such as meat, dairy, and eggs, making it difficult for those following a plant-based diet to get enough. Recent studies show that B₁₂ deficiency is common in vegans and can lead to anaemia, nerve damage, and cognitive impairments. Vegans were found to consume considerably less B₁₂ than omnivores, taking in only 10% of the B₁₂ of the average omnivore.[v]

Iodine Deficiency

Iodine is crucial for thyroid function, as it supports the production of thyroid hormones that regulate metabolism, growth, and energy production. Vegans are at risk for iodine deficiency, as plant-based diets typically lack reliable sources of iodine. Dairy, eggs, and seafood are the primary sources of iodine, and while some plant-based foods (such as seaweed) do contain iodine, the levels can vary dramatically depending on where the seaweed is sourced. Vegans are particularly vulnerable to iodine deficiency, which can lead to hypothyroidism, fatigue, and weight gain.[vi]

Vitamin D3 Deficiency

Vitamin D₃ is vital for bone health, immune function, and mood regulation. Vitamin D is primarily obtained through sunlight exposure, but it’s also found in fatty fish, eggs, and dairy. Given the main food sources of vitamin D₃ are animal products, it’s more challenging for those following a vegan diet to obtain enough. Some plant-based foods are fortified with vitamin D₂; this form of vitamin D is less effective than D₃ in raising blood levels of vitamin D.[vii] Vegans are at a higher risk for vitamin D deficiency, particularly in winter and for people living in areas with limited sunlight.[viii]

Zinc Deficiency

Zinc is an essential trace mineral that plays a key role in immune function, protein synthesis, and wound healing. The bioavailability of zinc in plant foods is lower than in animal products due to the presence of phytates in legumes and grains, which inhibit zinc absorption. As a result, vegans may have a higher risk of zinc deficiency, which can affect immune function, skin health, and wound healing. In fact, vegans have a higher incidence of zinc deficiency compared to omnivores.[ix]

Omega‑3 Fatty Acids Deficiency

Omega‑3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are vital for heart health, brain function, and reducing inflammation. These fatty acids are primarily found in fatty fish, but for vegans, the plant-based alternative is alpha-linolenic acid (ALA), which is found in flaxseed, chia seeds, and walnuts. The body must convert ALA into EPA and DHA, but research suggests that this conversion process is inefficient. Vegans have significantly lower blood levels of omega‑3 fatty acids.[x]

Calcium Deficiency

Calcium is crucial for bone and dental health, muscle function, and nerve transmission. While dairy is the most well-known source of calcium, many plant-based alternatives—such as fortified plant milks, tofu, and leafy greens—can provide adequate amounts. However, research suggests that vegans often consume less calcium than nonvegans, perhaps because calcium absorption from plant sources can be impaired by oxalates found in calcium-rich plants, which may lead to a lower bone mineral density over time. Vegans show a substantially lower intake of calcium compared to vegetarians and omnivores.[xi]

While a well-planned vegan diet can meet most nutritional needs, certain deficiencies—particularly in iron, vitamin B₁₂, iodine, vitamin D₃, zinc, omega‑3s, and calcium—are more common. Regular monitoring of nutrient levels and strategic food choices can help prevent deficiencies. A naturopathic doctor (ND) can be a valuable resource in addressing these nutritional gaps, offering personalized guidance based on individual health profiles. NDs may recommend laboratory tests to assess nutrient levels, provide dietary strategies to optimize absorption, and suggest supplements tailored to fill specific gaps, and. By incorporating targeted supplementation into a balanced vegan lifestyle, individuals can support optimal health and reduce the risk of long-term deficiencies, ensuring that the benefits of plant-based eating are fully realized.

Dr. Colleen Hartwick, ND

Dr. Colleen Hartwick is a licensed naturopathic physician practising on North Vancouver Island, BC, with a special interest in trauma as it plays a role in disease.

campbellrivernaturopathic.com