Common nutritional deficiencies in vegan diets include vitamin B12, iron, omega-3 fatty acids, and calcium. Since B12 is primarily found in animal products, vegans often need to seek fortified foods or supplements to meet their needs. Iron absorption can also be lower from plant sources, creating a potential deficiency risk. Omega-3 fatty acids, critical for heart and brain health, are found in fish; vegans can benefit from algae-based supplements. Lastly, ensuring adequate calcium intake is crucial for maintaining strong bones, which may require fortified options or specific plant foods.