Americans Need Much More Vitamin D, Study Says

March 25, 2009 01:37 PM
by Cara McDonough
Vitamin D deficiencies were found in teens and adults, with possibly serious health risks. Could skin cancer prevention campaigns be partially to blame?

Levels of ‘Sunshine Vitamin’ Drop Dramatically

In a study published in the Archives of Internal Medicine, researchers found that between 1988 and 1994, 45 percent of a surveyed group had sufficient amounts of vitamin D—30 nanograms per milliliter or more—in their blood levels; ten years later, only 23 percent of those surveyed had at least that amount.

Study co-author Adit Ginde, an assistant professor at the University of Colorado Denver School of Medicine, said that while they anticipated a decrease in vitamin D levels, “the magnitude of the decline in a relatively short time period was surprising,” Scientific American reports. 
Only 3 percent of the 3,149 blacks sampled in 2004 had the recommended levels compared with 12 percent of 5,362 sampled 20 years ago; black people have more melanin in their skin, making it harder for the body to absorb the sun's ultraviolet rays and synthesize vitamin D.

Researchers are concerned because vitamin D deficits may play a role in many health risks, including cancer, heart disease and diabetes, according to studies.
New research confirms that older people can prevent fractures by taking vitamin D supplements, provided they take a high enough dose and take the supplement regularly, Reuters reports.

Ginde says the increased use of sunscreen and long sleeves, encouraged by skin cancer campaigns, may be partially to blame. A sunscreen with a 15-factor protection can cut the skin's vitamin D production by 99 percent, according to the study. There aren’t many sources of the vitamin in our diets, although salmon, tuna, mackerel and vitamin D-fortified dairy products provide some.

But even with confirmed benefits, determining proper vitamin D dosage can be difficult, experts say. Mary France Picciano, a senior nutrition scientist in the National Institutes of Health's Office of Dietary Supplements, says there is a “disagreement on how much vitamin D is needed,” according to the Scientific American story.

USA Today reports that beyond supplements, “getting 10 minutes of sunlight on exposed arms and legs two to three times a week” is another way to increase vitamin D levels, but that “must be weighed against the risk for skin cancer,” researchers say.

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Related Topic: Vitamin D and children

Other recent vitamin D studies have also concluded that children need more of the vitamin than they currently get.

The American Academy of Pediatrics stated in October 2008 that infants—especially those that are breast-fed—and children need double the amount of vitamin D than had previously been recommended.

The news came as mounting evidence linked a lack of the vitamin to Parkinson’s and other disorders, such as rickets, a condition in which bones become soft. Another study released earlier that year suggested that children who take vitamin D are less likely to develop type 1 diabetes later on.

A report released in February said that vitamin supplements as a whole may be largely unnecessary for children who eat a varied diet; on the other hand, children with poor nutrition, children who are less physically active and those from low-income homes may not be getting the vitamins and minerals they need.

The study, conducted by University of California, Davis researchers, found that for the children who need more vitamin supplements, cost appeared to be the biggest obstacle. The research showed that only 22 percent of children in households below the poverty line used vitamins, while 43 percent of households above the poverty line used them.

Reference: Vitamins


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