How much vitamin D should you take per day?

In countries with little sunlight, such as the Netherlands and Belgium, more than 90% of the population does not get enough vitamin D through diet. About half have a blood level that is considered too low. That sounds alarming, but whether you actually need supplements depends strongly on who you are.

Are you a healthy adult under the age of 75? Then the Endocrine Society does not recommend additional vitamin D beyond the usual daily recommendation. Clinical studies found no evidence that extra supplementation prevents disease in this group. So you do not need to start taking it as a matter of course.

For four specific groups there is good support for supplementation. Children aged 1 to 18 can use it to prevent bone disease (rickets) and may get fewer respiratory infections. People aged 75 and older may see a lower risk of death. Pregnant women can reduce the risk of high blood pressure late in pregnancy and preterm birth. And people at greatly increased risk of type 2 diabetes may be able to delay the progression to diabetes. The exact dose has not yet been definitively established for any of these groups.

Regarding dose and safety: 2000 IU per day brings blood levels to a safe level in virtually all adults, and large studies found no side effects with use over several years. Higher doses of 4000 or 10,000 IU per day actually reduced bone density in the wrist and shin compared with a low dose of 400 IU in a three-year study. More is therefore not better here. For older adults living independently or in a care facility, 700 to 800 IU per day combined with calcium helps reduce the risk of falls and fractures. Among nursing home residents, 800 IU plus 1000 mg of calcium per day reduced the number of fractures by approximately 30%. When supplementation is indicated, it is best to take vitamin D daily rather than in large irregular doses.