The tolerable upper intake levels of vitamin D-3 vary based on age, reports National Institutes of Health. The tolerable upper intake level of a nutrient is the maximum daily intake amount that is not likely to cause adverse health effects.
Other than in the case of vitamin D deficiency, infants under the age of 6 months old are advised not to exceed 1,000 international units daily, and babies 7 to 12 months old are advised not to exceed 1,500 international units daily. Toddlers ages 1 to 3 years old are advised not to exceed 2,500 international units daily, while children ages 4 to 8 are advised not to exceed 3,000 iternational units daily. Individuals ages 9 and above are advised not to exceed 4,000 international units daily, says National Institutes of Health.