For people aged between 1 and 70 years old, the recommended daily allowance for vitamin D is 600 international units per day, says MedlinePlus. The daily intake should not exceed 4,000 IU per day, as higher doses than this may cause vitamin D toxicity.
For infants, the daily allowance is reduced to 400 IU, and for people over the age of 71, the daily allowance goes up to 800 IU. It is recommended that pregnant and lactating women take the normal dose of 600 IU, says WebMD.
Vitamin D toxicity has been shown to occur when daily doses over several months of 50,000 IU have been taken, says Mayo Clinic