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  • 500 mg
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This vitamin is key to red blood cell formation. It's naturally found in animal products, such as fish, meat and poultry, but also in foods fortified with synthetic B vitamins, such as some breakfast cereals. There are no known adverse effects to taking higher quantities of B-12, so health officials have set no upper intake limit. But the Office of Dietary Supplements notes that the vitamin can interact negatively with some medications, such as one used to treat diabetes and another for peptic ulcer disease.

Also known as ascorbic acid, the antioxidant is found in many fruits and vegetables, including oranges and red peppers. Health officials have set an upper limit of 2,000 milligrams per day. Vitamin C absorption drops significantly after 1,000 mg per day, according to the National Academy of Medicine, which also noted that doses of more than 3,000 mg per day may lead to gastrointestinal irritation.

Key to bone growth, vitamin D is produced when the body is exposed to ultraviolet rays in sunlight. But it's also found in milk or orange juice that has been fortified with synthetic vitamin D. Health officials have set an upper intake limit of 4,000 international units (IU) per day. The government's Office of Dietary Supplements warns that extremely high doses of the vitamin can damage the heart, blood vessels and kidneys.

This antioxidant can be found naturally in nuts, seeds and vegetable oils. While there's no evidence of adverse effects from consuming vitamin E through foods, high doses can cause hemorrhaging in animals. Health officials have set an upper limit of 1,500 international units (IU) per day. In large doses, the government's Office of Dietary Supplements says the vitamin may increase the risk of prostate cancer.

Essential for bone health, calcium helps fend off osteoporosis. The mineral is best absorbed when taken in doses of 500 milligrams or less, according to the National Academy of Medicine. Health officials have set an upper limit of 2,500 mg per day for adults 19-50 years, and 2,000 mg per day for those 51 and older. The Office of Dietary Supplements notes that excessive quantities of calcium can cause kidney stones and other issues.

Vitamin B-12, 500 mcg

8,333%

of the daily value recommended by the FDA (6 mcg)

83 bowls of cereal

contain an equivalent amount of vitamin B-12. (The daily value is equal to one bowl of fortified cereal.)

Vitamin B-12, 5000 mcg

83,333%

of the daily value recommended by the FDA (6 mcg)

833 bowls of cereal

contain an equivalent amount of vitamin B-12. (The daily value is equal to one bowl of fortified cereal.)

Vitamin C, 500 mg

833%

of the daily value recommended by the FDA (60 mg)

7 oranges

contain an equivalent amount of vitamin C. (The daily value is equal to about one orange.)

Vitamin C, 1000 mg

1,667%

of the daily value recommended by the FDA (60 mg)

14 oranges

contain an equivalent amount of vitamin C. (The daily value is equal to about one orange.)

Vitamin D, 1000 IU

250%

of the daily value recommended by the FDA (400 IU)

9 cups of milk

contain an equivalent amount of vitamin D. (The daily value is equal to about 3.5 cups of fortified milk.)

Vitamin D, 10000 IU

2,500%

of the daily value recommended by the FDA (400 IU)

87 cups of milk

contain an equivalent amount of vitamin D. (The daily value is equal to about 3.5 cups of fortified milk.)

Vitamin E, 400 IU

1,333%

of the daily value recommended by the FDA (30 IU)

6 jars of peanut butter

contain an equivalent amount of vitamin E. (The daily value is equal to a little less than a half jar of natural peanut butter.)

Vitamin E, 1000 IU

3,333%

of the daily value recommended by the FDA (30 IU)

15 jars of peanut butter

contain an equivalent amount of vitamin E. (The daily value is equal to a little less than a half jar of natural peanut butter.)

Calcium, 500 mg

50%

of the daily value recommended by the FDA (1000 mg)

1.6 slices of cheddar cheese

contain an equivalent amount of calcium. (The daily value is equal to about three slices of cheddar cheese.)

Calcium, 1200 mg

120%

of the daily value recommended by the FDA (1000 mg)

4 slices of cheddar cheese

contain an equivalent amount of calcium. (The daily value is equal to about three slices of cheddar cheese.)

Sources: U.S. Food and Drug Administration; the National Academy of Medicine; the National Institutes of Health’s Office of Dietary Supplements. Dosages were selected to demonstrate the range offered by commercially available products. Daily values set by the FDA are for adults and children four and older.