Recommended daily amounts for vitamins are set by the Institute of Medicine and are referred to as the dietary reference intake, or DRI. For most vitamins, the DRI increases with age. This is because, for the most part, vitamin intake is proportional to calorie intake, and adults need more calories than children.
Vitamin A
Vitamin A can be obtained through both animal and plant foods. However, animal sources, called retinol, are readily available to the body. Plant sources, called carotenoids, must be converted to retinol by the body so they are not as readily available. You need 12 to 24 units of a plant source of vitamin A to make just one unit of retinol. Therefore, vitamin A recommendations are given in retinol activity equivalents, or RAE. The DRI for vitamin A is 300 mcg RAE for children one to three, 400 mcg RAE for children four to eight, 600 mcg RAE for children nine to 13, 700 mcg RAE for females over 14 and 900 mcg for males over 14. Most orange fruits and vegetables are high in vitamin A, as are liver, spinach and kale.
B Vitamins
DRI values vary for each of the B vitamins, which are present in fish, meat and eggs. They are similar for thiamin, riboflavin and B-6, with children needing between .5 mg and 1 mg and adults needing 1.1 to 1.7 mg. Pantothenic acid and niacin are needed in larger amounts, with children needing 2 to 4 mg of pantothenic acid and 6-12 mg of niacin. Teenagers and adults need 5 mg of pantothenic acid and 14 to 16 mg of niacin. B-12, folate and biotin are needed in smaller amounts so DRI values are given in mcg. Children need 9 to 1.8 mcg of B-12 and adults need 2.4 mcg. Children need 150 to 300 mcg of folate and 8 to 29 mcg of biotin. Adults need 30 mcg of biotin and 400 mcg of folate.
Vitamin C
Like most vitamins, the vitamin C intake increases with age. Infants need 40 to 50 mg, children one to three need 15 mg, children four to eight need 25 mg, children nine to 13 need 45 mg, teenage girls need 5 mg, teenage boys and adult women need 75 mg and adult men need 90 mg. Citrus fruits, peppers, kiwi fruits, broccoli and strawberries are high in vitamin C.
Vitamin D
Vitamin D is one of the few vitamins that older adults need in higher amounts than younger adults. Infants, children and younger adults need 5 mg, adults between 50 and 70 need 10 mg and adults over 70 need 15 mg. Vitamin D is present in fatty fish, liver, cheese and egg yolks. Milk is usually fortified with vitamin D.
Vitamin E
The DRI for vitamin E is 4-5 mg for infants, 6 mg for children one to three, 7 mg for children four to eight, 11 mg for children nine to 13 and 15 mg for those over 14 years of age. Vitamin E is found in vegetable oils, nuts, and green vegetables.
Vitamin K
Vitamin K, which is important for blood clotting, is found in most green vegetables, cereals and soybeans. The DRI for vitamin K is 30 mcg for children one to three, 55 to 60 mcg for children four to 13, 75 mcg for teenagers and 90 mcg for adults.
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