There are many variables to adequate sun exposure.BPS 5 ReviewMost research recognizes that people with darker skin absorb less sunlight and may require more time in the sun. Winter, especially above 34 degrees latitude, is also a time when Vitamin D levels decline, due to less sunlight, and heart problems rise.
Finally, sunscreen rated at 8 or above will block most of the healthy UVB rays necessary to absorb Vitamin D. Of course, burned skin isn’t healthy and won’t absorb Vitamin D properly.
Additionally, older people spend less time in the sun and their kidneys are less efficient at converting sunlight into Vitamin D. For those who are overweight, the fat-soluble Vitamin D absorbs into the fat cells and is less available for a healthy body.
Inevitably, most people think of milk or multiple vitamins as Vitamin D sources. However, since a glass of milk only contains about 115 to 124 IU of Vitamin D it is a poor source. Additionally, most multiple vitamin sources contain 200IU to 400IU of Vitamin D. Clearly, these are not very potent sources.