A high percentage of American children have low levels of vitamin D—a deficiency that could lead to a host of health problems, ranging from respiratory diseases to weak bones to the common cold—according to a recent study from Harvard-affiliated hospitals and the University of Colorado School of Medicine.

The study found that almost one-fifth of American children do not have enough of the vitamin, according to standards set by the American Academy of Pediatrics.

Almost 90 percent of African American children and 80 percent of Hispanic children were found to be vitamin D deficient.

According to Jonathan M. Mansbach—lead author of the study and an assistant professor of pediatrics at Harvard Medical School—vitamin D is acquired primarily through sun exposure and food consumption.

He said he attributes the higher proportion of vitamin D deficiency among populations with darker skin tones to the greater amounts of melanin in their skin. As melanin impedes vitamin D production, it takes significantly longer for someone with darker skin to produce the adequate amounts.

But he added that the causes for the vitamin deficiency are far more complex, including the increased amounts of time children now spend indoors, the widespread usage of sunscreen, and geographic location.

To remedy this deficiency, Mansbach and his fellow researchers said they strongly recommend that children take vitamin D supplements.

According to Mansbach, vitamin D research has grown very “hot” in the past five years as its significance in the body’s metabolic pathways has become more evident.

Deficiency of this crucial vitamin in children has been associated with eczema, wheezing, type 1 diabetes, and weakened bones.

“Although hard evidence showing that low levels of vitamin D lead to diseases or that high levels prevent them is lacking, this is an increasingly burgeoning area of research,” said Mansbach.

Data for the analysis was obtained from the 2001-2006 National Health and Nutrition Examination Survey, a comprehensive national survey of Americans. The study examined data from 5,000 children, aged between one and eleven.

The study—which was funded by the National Institutes of Health—was published online Monday by the journal Pediatrics.

A representative from the journal was not available for comment.

—Staff writer Helen X. Yang can be reached at hxyang@fas.harvard.edu.