Not necessarily, although supplements can be helpful. Vegans must ensure reliable sources of vitamin B12. This means taking a B12 supplement of at least 25 mcg if daily, or 1,000 mcg if two or three times a week, or consuming B12-fortified foods. Nondairy milks, veggie “meats,” breakfast cereals, or nutritional yeast with three servings totaling 4 mcg of vitamin B12 for the day or 100 percent of the daily value is generally sufficient, although amounts vary from one batch to another. To be on the safe side, you may want to take a 1,000-mcg B12 supplement once a week, even if you are using B12-fortified foods. As it turns out, all adults above the age of 50 years, regardless of diet, are advised to use the form of B12 in supplements or fortified foods, as it is better absorbed than that from animal products.
While we can produce our own vitamin D when our skin is exposed to ultraviolet B rays (sunlight), this approach has its limitations due to people living at northern latitudes, being indoors, and using sunscreen. There is strong evidence that suboptimal vitamin D status compromises bone health and increases risk of disease. Low levels of vitamin D are common in populations throughout the world, including in vegan populations. Everyone should strive to meet recommended intakes for vitamin D, especially when their sun exposure is limited. Although some foods are fortified with vitamin D, it can be a challenge to meet needs through diet alone. In this case, a supplement is advised.