The first in a series of reports on Dietary Reference Intakes (DRIs) by the Institute of Medicine (IOM) covers the nutrients associated with bone growth and osteoporosis. The report, “Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride,” recommends intake levels for U.S. and Canadian individuals and population groups and, for the first time, sets upper level guidelines to reduce the risk of adverse health effects from consuming too much of a nutrient. The new guidelines have different age categories, nutritional measures and recommended intake levels. The most significant changes in the report were seen with calcium.
According to the new guidelines, Americans and Canadians should consume between 1,000 and 1,300 mg of calcium per day. Children and adolescents nine to 18 years of age and adults over the age of 50 years need calcium in the higher range (1,300 and 1,200 mg, respectively), a substantial increase from the amount recommended in previous guidelines for these age groups. The calcium recommendations were set at levels associated with maximum retention of body calcium, because bones that are rich in calcium are known to be less susceptible to fractures. In addition to calcium consumption, other factors that are thought to affect bone retention of calcium and risk of osteoporosis include high rates of growth in children during specific periods, hormonal status, exercise genetics and other diet components.
The report recommends that individuals who wish to increase their calcium intake should do so through conventional foods, fortified foods, supplements or a combination of these three. Supplements are recommended for persons at high risk of health problems related to low calcium intake.
DRI values include recommended dietary allowance (RDA), adequate intake (AI), estimated average requirement (EAR) and tolerable upper intake level. In this first report in the series, RDAs were set for some nutrients. An AI was established if there was insufficient information to recommend an RDA. AI levels (see table)
and a tolerable upper intake level were established for calcium. The upper limit for calcium is 2,500 mg per day for all persons one year of age and older. The upper limit figure is not intended by the IOM to be a recommended level of intake, and the IOM stresses that there is no established benefit for individuals to consume nutrients at levels above the RDA or AI. The tolerable upper intake level refers to total intakes from food, fortified food and nutrient supplements. The EAR is an intake that meets the estimated nutrient need of one half of the individuals in a specific group.
The DRIs were derived by a panel of experts appointed by the National Academy of Sciences who spent one year reviewing the scientific studies of the various nutrients associated with bone growth and osteoporosis. The panel considered the roles of these nutrients in decreasing the risk of chronic and other diseases and conditions and interpreted the current data on intakes in the U.S. and Canadian population groups. Subsequent reports will focus on at least six other nutrient groups, all of which will be managed by the IOM Food and Nutrition Board's Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. The six additional groups are folate and other B vitamins; antioxidants (e.g., vitamins C and E, selenium); macronutrients (e.g., protein, fat, carbohydrates); trace elements (e.g., iron, zinc); electrolytes and water; and other food components (e.g., fiber, phytoestrogens). The recommendations for folate and other B vitamins should be announced this spring.
The IOM recommendations have been given to various government agencies. It is planned that a subcommittee will be established to determine the uses of the DRIs in various settings.
The complete report can be ordered on the Internet site of the National Academy Press, at http://www.nap.edu
. Copies may also be ordered by calling 800-624-6242 or 202-334-3313.