Adopting a vegan diet can provide many health benefits, but some nutrients are less abundant in plant-based foods and may require supplementation to avoid deficiency. This article outlines key supplements commonly considered in a vegan diet, the rationale behind them, and practical, evidence-based considerations. Vitamin B12 is essential for nerve function, red blood cell production, and DNA synthesis. Because B12 is not reliably available from unfortified plant foods, supplementation is generally recommended for vegans. Common supplemental forms are cyanocobalamin and methylcobalamin; cyanocobalamin is stable and widely used, while methylcobalamin may be preferred by some individuals. Typical supplemental doses range from 25 to 500 mcg daily or larger intermittent doses, depending on testing and clinical guidance. Vitamin D supports bone health and immune function and is synthesized in the skin with UV exposure. In regions with limited sun exposure or during winter, vegans often use supplements containing vitamin D2 or vegan D3 (lichen-derived). D3 is generally more effective at raising serum 25(OH)D levels. Common daily intakes for maintenance are 1,000–2,000 IU, but individual requirements vary based on baseline status and medical advice. Omega-3 fatty acids, particularly EPA and DHA, support cardiovascular and cognitive health. Plant foods provide ALA (alpha-linolenic acid), but the conversion to EPA/DHA is limited. Algae-derived omega-3 supplements supply preformed EPA and/or DHA suitable for vegans and are an evidence-based alternative to marine sources. Iron is required for oxygen transport and energy metabolism. Plant-based diets supply non-heme iron, which is less readily absorbed than heme iron from animal foods. Iron supplements for vegans often use ferrous bisglycinate or ferrous sulfate; combining iron intake with vitamin C-rich foods enhances absorption. Routine monitoring of ferritin and hemoglobin can guide whether supplementation is necessary to correct or prevent deficiency. An organic vegan multivitamin can help cover multiple potential gaps in one product. Key nutrients to evaluate on the label include vitamin B12, vitamin D, iron (if needed), zinc, calcium, and iodine. Choosing products with transparent sourcing, clear dosing, and third-party testing supports product quality, while avoiding reliance solely on supplements over a varied diet. When selecting supplements, consider product purity, verified vegan certification, and absence of unnecessary fillers or allergens. Evidence supports targeted supplementation based on identified needs rather than indiscriminate high-dose use. Laboratory testing (e.g., serum B12, 25(OH)D, ferritin) and consultation with a healthcare professional help personalize choices and dosing. For additional information on supplement quality and formulation, see the Dr. Mercola supplements overview and other resources such as Additional supplement resources. A general site reference is available at Topvitamine homepage. For a concise guide to the most relevant supplements for someone following a plant-based diet, consult this summary: [Best supplements guide at Topvitamine](https://www.topvitamine.com/blogs/news/best-supplements-for-a-vegan-diet-topvitamine) and the related product and information pages like Best Supplements for a Vegan Diet. Testing, individualized advice, and a baseline of nutrient-dense whole foods remain the foundation of a healthy vegan diet. Supplements can safely and effectively address common shortfalls when used thoughtfully and under clinical supervision.