Deficiencies in nutrients and vitamins often vary by age, gender, race and ethnicity, according to a recent report by the Centers for Disease Control and Prevention.

The most significant deficiency involves blacks and vitamin D. Thirty-one percent of that population has insufficient levels of the vitamin, compared with 12% of Mexican-Americans and 3% of whites.

The findings were released April 2 in the CDC’s second national report on biochemical indicators of diet and nutrition in the U.S. The study did not examine causes of the reported deficiencies.

However, it is known that higher concentrations of melanin in dark skin tend to block the sun’s ultraviolet rays, said internist Raul Seballos, MD. As a result, people with dark skin do not convert as much UV rays into vitamin D as do individuals with lighter skin, which can lead to a deficiency in the nutrient, said Dr. Seballos, vice chair of preventive medicine at Cleveland Clinic.

Patients and physicians should be aware of common nutrient and vitamin deficiencies among various populations, said Christine Pfeiffer, PhD, chief of the CDC’s Nutritional Biomarkers Branch.

“Research shows that good nutrition can help lower people’s risk for many chronic diseases,” said Pfeiffer, who contributed to the report.

Researchers examined the blood and urine levels of 58 diet-and-nutrition biochemical indicators among participants in the 2003-06 National Health and Nutrition Examination Survey. The report defines a biomedical indicator as a nutrient, metabolite or dietary indicator with potential health relevance that can be measured in blood or urine.

Data show that the overall rate of nutrient deficiencies in the general U.S. population ranges from less than 1% for folate and vitamins A and E to about 10% for iron and vitamins B6 and D.

“For most nutrients, deficiency rates less than 10% are encouraging, but higher deficiency rates in certain age and race/ethnic groups are a concern and need additional attention,” Pfeiffer said.

The report found that 16% of blacks had insufficient levels of iron. Rates of iron insufficiency also were elevated among Mexican-American women of child-bearing age (13%) and Mexican-American children ages 1 to 5 (11%).

Iodine levels in young women ages 20 to 39 were close to insufficient. Iodine is an essential component of thyroid hormones that regulate human growth and development.

Among the positive findings was that folate levels in all race/ethnic groups have improved due largely to the fortification of cereal-grain products with folic acid in 1998. Overall folate deficiency has remained at less than 1% since fortification, according to the report.

Pfeiffer said diet and environmental factors, such as smoking, probably are the leading cause of variations in people’s levels of vitamins and nutrients.

Dr. Seballos encourages physicians to ask patients during office visits about what types of foods they eat, how many meals are prepared at home and how often they eat out. Answers to those questions can help determine if patients are getting the proper amounts of nutrients and vitamins they need.

“These questions are just as important as questions about how much patients exercise and how much alcohol they drink,” he said.

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