Cornell nutritionist Patsy Brannon, Ph.D. '79, recently served on an Institute of Medicine (IOM) panel that issued new recommendations for calcium and vitamin D consumption to ensure the bone health of most Americans and Canadians.
The IOM report, released in November 2010, triples the recommended vitamin D intake for most healthy people ages 1-70 to 600 international units (IUs) per day from 200 IUs set in 1997. It also caps the suggested vitamin D intake for most at 4,000 IUs per day, citing links between elevated vitamin D blood levels and adverse effects, including kidney and tissue damage.
Brannon, professor in the Division of Nutritional Sciences, attributes the latest recommendations to "considerably more evidence available in the last 14 years [that] allowed us to determine the needs of the population more precisely."
The IOM Committee to Review Dietary Reference Intakes for Vitamin D and Calcium, composed of 14 physicians and nutritionists from the United States and Canada, reviewed more than 1,000 studies and reports and consulted many scientists and stakeholders.
The updated recommendations will influence food policy on many levels, including U.S. Department of Agriculture standards for school meals, nutrition information on food packages and the content of meals ready-to-eat (MREs), rations eaten by soldiers in the field. Health professionals also take the guidelines into account when advising patients on diet and lifestyle.
Even with the sharp increase in daily intake levels, the panel found that few people in the United States or Canada lack adequate vitamin D, in part because sunlight provides enough of the nutrient to overcome dietary deficiencies.
"Contrary to the highly publicized epidemic of vitamin D deficiency in America and Canada, the average American and Canadian is meeting his or her needs for vitamin D," Brannon said. The IOM panel defined as sufficient a blood level of 20 nanograms per milliliter as measured by the 25-hydroxy vitamin D test.
The findings also counter recent studies suggesting that insufficient vitamin D levels may be linked to a host of chronic conditions, including cancer, diabetes, autoimmune disorders, and heart and cardiovascular disease.
"The evidence available is inconsistent, with some studies demonstrating this association while others show no association, and still others show evidence of adverse effects with high blood levels of vitamin D," Brannon said. "Thus, it is not possible to conclude whether there is an association of low vitamin D with chronic disease or not."
Brannon noted that dark-skinned individuals and the elderly may be most at risk for vitamin D deficiency because their skin produces less of the nutrient when exposed to sunlight. In addition, she said, obese people could be at greater risk for deficiency because their bodies quickly break down vitamin D and store it in fat cells rather than putting it to use in the body.
"Our recommendations are for healthy people," Brannon added. "People with medical conditions need to consult their health care providers to discuss how their specific conditions and health impact their vitamin D needs and blood values."
For a complete listing of recommended intakes by age group and gender, visit http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/DRI-Values.aspx.
Ted Boscia is assistant director of communications for the College of Human Ecology.