They must obtain the vitamin through regular use of a vitamin B 12 source such as fortified soy milk or yeast, or a vitamin B 12 supplement. Vitamin D is required to absorb calcium from the digestive tract and to incorporate calcium into bones and teeth. Therefore, vegetarians, especially vegans, may not get enough. Another source of vitamin D is sunlight. The body makes vitamin D from sunlight on the skin.
People regularly exposed to sunlight can get enough vitamin D without having any come from food.
However, sun exposure can be limited by several factors, including dark skin, pollution and northern latitudes. If sun exposure is limited and there are no animal products in the diet, a vitamin D supplement is needed. Minerals Calcium is needed for strong bones and teeth, for normal blood clotting, and for normal muscle and nerve function. Most calcium in the American diet comes from milk and milk products. When these foods are avoided, calcium must come from other sources.