Vitamin deficiencies in vegan diets
Pro Research Analysisby 
Searched over 200M research papers
Common Vitamin Deficiencies in Vegan Diets
Research consistently shows that vegan diets are at risk for several vitamin and mineral deficiencies, most notably vitamin B12, vitamin D, calcium, iodine, zinc, and sometimes iron and selenium. These nutrients are primarily found in animal products, making it difficult for vegans to obtain adequate amounts through plant-based foods alone. Deficiencies in these vitamins and minerals can lead to health problems such as anemia, osteoporosis, neurological disorders, and thyroid issues if not properly managed 15810.
Vitamin B12 Deficiency in Vegan Diets
Vitamin B12 deficiency is the most well-documented risk for vegans. Studies show that unsupplemented vegan diets result in significantly lower B12 intake and status compared to omnivorous and vegetarian diets, leading to a higher risk of functional B12 deficiency and related health issues such as anemia and neurological symptoms 2345679. Even short-term adherence to a vegan diet can quickly reduce B12 biomarkers in the body . The prevalence of B12 deficiency among vegans varies widely, from 5% to over 50%, depending on supplement use and regional dietary habits . Regular supplementation or consumption of B12-fortified foods is strongly recommended to prevent deficiency 368910.
Other Vitamin and Mineral Deficiencies
Besides B12, vegan diets are often low in vitamin D, calcium, iodine, and zinc. Vitamin D and calcium are important for bone health, and their deficiency can increase the risk of osteoporosis. Iodine deficiency is also common, especially in regions where iodized salt is not widely used, and can lead to thyroid dysfunction 158. Zinc and selenium are also sometimes low in vegan diets, which can affect immune function and other metabolic processes 15.
The Role of Supplementation and Fortified Foods
Most studies agree that with careful dietary planning and the use of supplements or fortified foods, vegans can meet their nutritional needs and avoid deficiencies. Supplementation is particularly important for vitamin B12, vitamin D, and iodine. In populations where supplement use is common, the prevalence of deficiencies is much lower, and vegans can maintain similar vitamin and mineral status as omnivores 810. However, economic and accessibility barriers to supplements and fortified foods can make it challenging for some individuals to maintain adequate nutrient intake .
Health Implications and Recommendations
Vitamin and mineral deficiencies in vegan diets can lead to a range of health issues, including anemia, bone loss, neurological symptoms, and thyroid problems. These risks are especially pronounced in vulnerable groups such as pregnant and lactating women, adolescents, and those with limited access to supplements 147. Health professionals recommend regular monitoring of nutrient status and personalized supplementation strategies for individuals following a vegan diet 136.
Conclusion
Vegan diets can offer significant health and environmental benefits, but they require careful planning to avoid vitamin and mineral deficiencies. Vitamin B12, vitamin D, calcium, iodine, and zinc are the most common nutrients of concern. Regular use of supplements or fortified foods, along with periodic monitoring of nutrient status, is essential for maintaining health on a vegan diet. With proper management, vegan diets can be nutritionally adequate and support long-term well-being 135810.
Sources and full results
Most relevant research papers on this topic