The recommended daily intake of vitamin D varies depending on various factors and it is best to consult with a family doctor for personalized recommendations. In Switzerland, the nutrient reference values suggest that healthy men and women should aim for 15 to 20 μg (600-800 IU) of vitamin D per day from food, supplements, and endogenous production. The upper safe intake level is considered to be 100 μg (4000 IU) per day.