The typical daily dosage of vitamin D-3 from food intake alone is 204 to 288 international units depending on gender and life stage, according to the National Institutes of Health. The recommended daily supplementation dosage is 400 to 2,000 international units, reports WebMD.
Vitamin D-3 is naturally present in some foods and is produced in the human body when ultraviolet rays from the sun strike the skin. Vitamin D deficiencies occur as the result of dietary inadequacies, impaired absorption or increased excretion, explains the National Institutes of Health. Vitamin supplementation is recommended to support the dietary intake of vitamin D-3 and prevent the common diseases associated with vitamin D-3 deficiency, osteomalacia and rickets. The individualized dosage of dietary supplements depends on the targeted goals of supplementation. For example, 400 to 1,000 international units of vitamin D-3 are recommended to prevent osteoporosis in older adults, and 1,200 international units are recommended to prevent influenza. Most common vitamin supplements only contain 400 international units of vitamin D-3.