These vitamins help the process your body uses to get or make energy from the food you eat. They also help form red blood cells. You can get B vitamins from proteins such as fish, poultry, meat, eggs, and dairy products. Leafy green vegetables, beans, and peas also have B vitamins. Many cereals and some breads have added B vitamins. Not getting enough of certain B vitamins can cause diseases. A lack of B12 or B6 can cause anemia. 1  Vitamin B12 (National Institutes of Health, Office of Dietary Supplements) Also in Spanish.  Vitamin B6 (National Institutes of Health, Office of Dietary Supplements) Also in Spanish.