Vitamins
Vitamin D
Last Updated on Sunday, 28 February 2010 21:09
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements. Vitamin D is essential for promoting calcium absorption in the gut and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany.
Vitamin D is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts. Without sufficient vitamin D, bones can become thin, brittle, or misshapen.
Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Vitamin D has other roles in human health, including modulation of neuromuscular and immune function and reduction of inflammation. Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D.
Recommended Intake
The Food & Nutrition Board at the Institute of Medicine of the National Academies established adequate daily dietary intake allowances for vitamin D. They are listed below in micrograms (mcg) per day.
| Age | Children | Men | Women | Pregnancy | Lactation |
|---|---|---|---|---|---|
| Birth to 13 years | 5 mcg (200 IU) | ||||
| 14-18 years | 5 mcg (200 IU) | 5 mcg (200 IU) | 5 mcg (200 IU) | 5 mcg (200 IU) | |
| 19-50 years | 5 mcg (200 IU) | 5 mcg (200 IU) | 5 mcg (200 IU) | 5 mcg (200 IU) | |
| 51-70 years | 10 mcg (400 IU) | 10 mcg (400 IU) | |||
| 71+ years | 15 mcg (600 IU) | 15 mcg (600 IU) |
Sources of Vitamin D
| Food | International Units per serving* | Percent Daily Value* |
|---|---|---|
| Cod liver oil, 1 tablespoon | 1,360 | 340 |
| Salmon (sockeye), cooked, 3 ounces | 794 | 199 |
| Mushrooms that have been exposed to ultraviolet light to increase vitamin D, 3 ounces (not yet commonly available) | 400 | 100 |
| Mackerel, cooked, 3 ounces | 388 | 97 |
| Tuna fish, canned in water, drained, 3 ounces | 154 | 39 |
| Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup | 115-124 | 29-31 |
| Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies) | 100 | 25 |
| Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV) | 80 | 20 |
| Margarine, fortified, 1 tablespoon | 60 | 15 |
| Sardines, canned in oil, drained, 2 sardines | 46 | 12 |
| Liver, beef, cooked, 3.5 ounces | 46 | 12 |
| Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV) | 40 | 10 |
| Egg, 1 whole (vitamin D is found in yolk) | 25 | 6 |
| Cheese, Swiss, 1 ounce | 6 | 2 |
*Daily Values were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents among products within the context of a total daily diet. The Daily Value for vitamin C is 400 international units for adults and children age 4 and older. Foods providing 20 percent of more of the Daily Value are considered to be high sources of a nutrient, but foods providing lower percentages of the Daily Value also contribute to a healthful diet.
