The high incidence of vitamin D deficiency was so surprising that "we sat on our data for six months," Melamed said. "We didn't publish until it was confirmed by other people that we had the right numbers."
Children with the lowest vitamin D levels were more likely to have higher blood pressure, high blood sugar levels and low blood levels of HDL ("good") cholesterol, the study found.
It's not entirely certain that low levels of vitamin D early in life will translate into health problems in the adult years, Melamed said. "But if you have hypertension [high blood pressure] at age 20, you have 60 more years of dealing with the consequences," she noted.
The study led by Reis was a detailed cross-sectional analysis of data on 3,577 adolescents. It found an average vitamin D blood level of 24.8 nanograms per milliliter. The average level was 15.5 nanograms per milliliter in blacks, 21.5 in Mexican Americans and 28 in whites.
There was a clear association with cardiovascular risk factors. The 25 percent of youngsters with the lowest levels of vitamin D were 2.36 times more likely to have high blood pressure, 54 percent more likely to have low HDL cholesterol levels, 2.54 times more likely to have elevated blood sugar levels and 3.88 times more likely to have metabolic syndrome, a constellation of risk factors including obesity, high blood fats and high blood pressure.
But the results should not panic parents, Reis said. "I believe we need additional research," he said. "Our study is observational, and we need additional studies to confirm it."
Specifically, parents need not turn to supplements to provide the recommended intake of vitamin D, currently set at 200 International Units a day for everyone up to age 50, Reis said. Adequate vitamin D intake can be achieved with 15 minutes a day of exposure to sunlight or consuming fortified milk, bread an
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