In November 2010, the Food and Nutrition Board of the Institute of Medicine, or IOM, released a consensus report resulting from an exhaustive review of over 1000 studies addressing vitamin D and calcium. Within this comprehensive review is an update of the dietary reference intakes, or DRIs, for these nutrients, replacing the adequate intakes, or AIs, established in 1997. In addition, more than 25 health outcomes were assessed, and vitamin D's role in bone health was reconfirmed; however, significant and clear evidence of the role of vitamin D in other health conditions, such as cancer, was not currently supported by available clinical research.
Recommended Dietary Allowance
The recommended dietary allowance, or RDA, is defined as the value that sufficiently meets the needs of approximately 97.5 percent of the population. The committee set the RDA for vitamin D at 600 international units per day, or 600 IU/d, for children who are 1 to 18 years of age and adults under the age of 70 years. Individuals over the age of 70 years may require up to 800 IU/d. These recommendations were based on the assumption of minimal sunlight exposure and include total vitamin intake from both supplements and food intake. In other words, you may be able to obtain the full recommended amount from dietary sources alone, but a supplement may be called for if you are not able to obtain the recommended amount from food consumption alone.
Estimated Average Requirement
The estimated average requirement, or EAR, is the value that meets the needs of approximately 50 percent of the population within a given group. The EAR for vitamin D is 400 IU, meaning that the committee concluded that North Americans of all ages on average need 400 IU of vitamin D per day.
Tolerable Upper Level Intake
The upper level intake, or UL, is the value at which intakes above it run the risk of adverse effects. The UL set for vitamin D intake for adults is 4000 IU/d and ranges from 1000 to 3000 IU/d for the pediatric population, depending on age. In addition, dosages between the RDA and the UL do not show evidence of providing additional benefits.
Other Committee Recommendations
The committee recommended the need for standardization in laboratory testing of vitamin D levels; the lack of this standardization appears to be adding confusion to the interpretation and diagnosis of vitamin D status in individuals. In addition, although the current clinical data does not sufficiently link vitamin D with non-bone health indicators such as cancer, the committee highly recommends that further research be conducted in these areas.
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