500 I.U. per drop of cholecalciferol from bottle. Suggested daily dose is under 4,000 i.u. twice daily but if in doubt dose should be adjusted by a physician. Dose is not for infants. Vitamin D3 assists absorption of calcium and phosphorus from the gut and helps regulate calcium meetabolism in the body. Provides general cellular support and boosts the immune system. Some integrative physicians claim a blood level of 70 to 80 will help prevent cancer. Too much D3 (above recommended level) may become toxic and periodic blood tests may be needed.