Why Do People Need Vitamins?

People need vitamins because vitamins cannot be synthesized in the body and are required for metabolism, according to Colorado State University. Most vitamins function as coenzymes in the body.

Vitamin A

• Carrots are an excellent source of vitamin A.

  Vitamin A helps mainly with vision, but also with bone growth, cell reproduction, cell division and cell differentiation, according to the Office of Dietary Supplements. Dietary sources of vitamin A include beef liver, chicken liver, fortified skim milk, cheese, carrots, spinach and kale.

Types

• Oatmeal is an excellent source of vitamin B6.

  Vitamin B6 helps with the breakdown of protein as well as red blood cell health, the nervous system and some areas of the immune system, according to the American Cancer Society. Dietary sources of vitamin B6 include bananas, potatoes, oatmeal, chicken breast and trout, according to the Office of Dietary Supplements.

Vitamin B12

• Salmon is an excellent source of vitamin B12.

  Vitamin B12 helps the body mainly with growth and development, but also produces blood cells and helps the nervous system, according to the American Cancer Society. Dietary sources of vitamin B12 include beef liver, clams, trout, salmon, yogurt and milk, according to the Office of Dietary Supplements.

Vitamin C

• Blueberries are an excellent source of vitamin C.

  Vitamin C helps the body repair tissue and is required to produce the protein collagen, according to Medline Plus. Dietary sources of vitamin C include mango, papaya, watermelon, sprouts, red bell peppers, blueberries and cranberries.

Vitamin D

• Milk is an excellent source of vitamin D.

  Vitamin D helps maintain calcium and phosphorus levels in blood and helps with the absorption of calcium, according to the Mayo Clinic. Dietary sources of Vitamin D include cod liver oil, mushrooms, salmon, mackerel, sardines, milk, tuna fish and fortified orange juice, according to the Office of Dietary Supplements.