May 3, 2010 -- Low vitamin D levels are commonly observed in children in northern states, often due to insufficient sunlight and dietary intake.
But emerging research indicates that young people who live in the South, where sunlight is ample, also have low vitamin D levels.
Vitamin D promotes bone growth and other important body functions. The body uses sunshine to make vitamin D, and it is also found in some foods.
Vitamin D and Teens
Researchers measured vitamin D levels in 559 African-American and white adolescents between 14 and 18 in Augusta, Ga., which gets plenty of sunlight year-round. Vitamin D levels were tested in all four seasons of the year.
Kids were excluded if they were taking medications or had chronic medical conditions that might affect growth and development or affect study results.
Of the 559 participants, 49% were female, 51% male, 45% African-American, and 55% white.
Researchers say participants were in various stages of maturation and that 268 of the 274 girls had started menstruation.
About half (56.4 %) of the youths tested had vitamin D insufficiency, meaning the level was low but not affecting health. But 28.8% had vitamin D deficiency -- a level low enough to cause health problems.
The vitamin D levels were lowest in winter. But African-American teenagers had significantly lower vitamin D levels in every season of the year, compared to white teens.
Also, adolescents with a higher body mass index had lower vitamin D levels.
Vitamin D Deficiency Higher in African-Americans
Overall, the researchers write, vitamin D levels were higher in white children than in African-American teens, and higher in boys than girls.
Researchers report that:
- Vitamin D insufficiency rates were 94.3% in African-American girls and 83.1% in African-American boys, compared with 29.6% in white girls and 30.3% in white boys.
- Vitamin D deficiency rates were 73.8% in African-American girls and 46.9% in African-American boys, compared with only 2.6% in white girls and 3.9% in white boys.
- Severe vitamin D deficiency was found only in African-American adolescents, or 5.2%.
- In summer, no white kids had vitamin D deficiency, but 55% of African-American youths did.
Adults Need Vitamin D, Too
Vitamin D deficiency can result in thin, brittle, or misshapen bones; having enough Vitamin D can prevent rickets in kids. It also helps to protect older adults from osteoporosis.
Researchers say their study is one of the first to investigate vitamin D status in children in the southern part of the U.S. in African-Americans as well as whites.
They also say that low levels of vitamin D is a growing national problem for young people in the U.S. regardless of where they live.
"One of the key findings in our study is that a substantial proportion of black adolescents may be at risk for low vitamin D status not only in winter but throughout the year," the researchers write.
Researchers say more work is needed to investigate the implications for low vitamin D status and how to improve the situation.