**3. Dietary recommendations of vitamin D**

The dietary recommendations are largely based on bone health and assuming a minimal sun exposure of an individual under study. While the safe upper limit is set at 4000 international unit/day (IU/d) for healthy adults, for pregnant women, doses are higher than 6000 IU/d. Based on limited data from randomized controlled trials, some authors suggest that pregnant women can be supplemented with 1000–2000 IU/d during the second and third trimesters, and a deficiency during pregnancy can be treated with daily doses of 4000 IU [5].
