Our body needs vitamin D to absorb calcium. Without enough vitamin D, one can’t form enough of the hormone calcitriol (known as the “active vitamin D”).
This in turn leads to insufficient calcium absorption from the diet. In this situation, the body must take calcium from its stores in the skeleton, which weakens existing bone and prevents the formation of strong, new bone.
The foods we eat contain a variety of vitamins, minerals, and other important nutrients that help keep our bodies healthy. Two nutrients in particular, calcium and vitamin D, are important at every age as they are need needed for strong bones, blood circulation and blood pressure, heart health.
*** Calcium is needed for our heart, muscles, and nerves to function properly and for blood circulation and clotting.
Although a balanced diet aids calcium absorption, high levels of protein and sodium (salt) in the diet are thought to increase calcium excretion through the kidneys. Excessive amounts of these substances should be avoided, especially in those with low calcium intake.
Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies (formerly National Academy of Sciences) provided Dietary Reference Intake (DRIs) values for vitamin D.
DRI values, which vary by age and gender, are a set of reference values used to plan and assess nutrient intakes of healthy people include RDA, AI and UL.
1. Recommended Dietary Allowance (RDA):
Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people.
2. Adequate Intake (AI):
established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy.
3. Tolerable Upper Intake Level (UL):
maximum daily intake unlikely to cause adverse health effects.
The FNB established an AI for vitamin D that represents a daily intake that is sufficient to maintain bone health and normal calcium metabolism in healthy people.
AIs for vitamin D are listed in both micrograms (mcg) and International Units (IUs); the biological activity of 1 mcg is equal to 40 IU. The AIs for vitamin D are based on the assumption that the vitamin is not synthesized by exposure to sunlight
Adequate Intake (AI) values for Vitamin D according the age
| Age | Children | Men | Women | Pregnancy | Lactation |
| Birth to 13 years | 5mcg (200 IU) |
||||
| 14-18 years | 5mcg (200 IU) |
5mcg (200 IU) |
5mcg (200 IU) |
5mcg (200 IU) |
|
| 19-50 years | 5mcg (200 IU) |
5mcg (200 IU) |
5mcg (200 IU) |
5mcg (200 IU) |
|
| 51-70 years | 10mcg (400 IU) |
10mcg (400 IU) |
|||
| 71+ years | 15mcg (600 IU) |
15mcg (600 IU) |
In 2008, the American Academy of Pediatrics (AAP) issued recommended intakes for vitamin D that exceed those of FNB. The AAP recommendations are based on evidence from more recent clinical trials and the history of safe use of 400 IU/day of vitamin D in pediatric and adolescent populations.
AAP recommends that exclusively and partially breastfed infants receive supplements of 400 IU/day of vitamin D shortly after birth and continue to receive these supplements until they are weaned and consume 1,000 mL/day of vitamin D-fortified formula or whole milk.
*** (All formulas sold in the United States provide 400 IU vitamin D3 per liter, and the majority of vitamin D-only and multivitamin liquid supplements provide 400 IU per serving.)
Similarly, all non-breastfed infants ingesting <1,000 mL/day of vitamin D-fortified formula or milk should receive a vitamin D supplement of 400 IU/day.
AAP also recommends that older children and adolescents who do not obtain 400 IU/day through vitamin D-fortified milk and foods should take a 400 IU vitamin D supplement daily.
The FNB established an expert committee in 2008 to review the DRIs for vitamin D (and calcium).
Determinations of DRIs are based on indicators of adequacy or hazard; dose-response curves; health outcomes; life-stage groups; and relations between intakes, biomarkers, and outcomes.
For vitamin D, the FNB committee will focus on (1) effects of circulating concentrations of 25(OH)D on health outcomes, (2) effects of vitamin D intakes on circulating 25(OH)D and on health outcomes, and (3) levels of intake associated with adverse effects.
The current DRIs for this nutrient were established in 1997, and since that time substantial new research has been published to justify a reevaluation of adequate vitamin D intakes for healthy populations.