Your D-Day Plan of Attack
Many vitamin D researchers are convinced the government's recommendations for adequate vitamin D intake are far below what your body really needs. Those guidelines call for 200 IU a day up to the age of 50, 400 IU from 51 to 70, and 600 IU over age 70.
But, says Holick, studies show that to achieve blood levels of vitamin D that can protect you against chronic diseases, you need an optimal dose of 1,000 IU of vitamin D a day. The vitamin is well absorbed from foods like fortified milk and from vitamin pills, whether taken alone or in combination with other foods.
So how can you get enough of this overlooked vitamin? Most foods aren't filled to the brim with vitamin D -- far from it. You can get 425 IU in a 3-ounce serving of salmon, and 270 IU in 3.5 ounces of canned sardines. But most foods provide much more modest amounts of vitamin D, from egg yolks (25 IU per egg) to cheddar cheese (2.8 IU per ounce).
"You'll get 200 IUs of vitamin D by drinking two glasses of fortified milk," says Sandon, spokeswoman for the American Dietetic Association. But at age 70, even reaching the government's recommended level of 600 IU from diet alone can be a challenge. "These people are probably not drinking six glasses of milk a day for various reasons, including a higher incidence of lactose intolerance in the elderly," she tells WebMD.
"We need more food fortification [with] vitamin D," says Susan Sullivan, DSc, RD, assistant professor in the department of food science and human nutrition at the University of Maine. "We need to make it easier for people to meet their vitamin D requirements through the food supply."
Some of that fortification is already happening. In addition to milk, a growing number of food manufacturers are adding vitamin D to yogurt, breakfast cereal, margarine, and orange juice. A cup of fortified orange juice, for example, contains 100 IU of vitamin D.
Here Comes the Sun
If you're striving for Holick's recommendation of 1,000 IU a day, you may have to turn to vitamin D supplements or the sun as your vitamin D savior. Regular sun exposure can stimulate the human skin to produce quantities of vitamin D that far exceed your needs. Without a shadow of a doubt, sunlight is the largest single source of vitamin D for most people.