Question

how much body should be exposed to sun for making vtamin d

Answer 1

there's not cartain that this much amount of body should be exposed to sunlight to gain vitamin .. it's that that how much body is exposed that much more vitamin we will gain... vitamin can be gained only in the morning

Answer 2

The time and amount of skin exposed depends on both your skin type and environmental conditions such as the UV index. In good UVB light conditions -- a UV index of 3 or higher, between 10:30 a.m. and mid-afternoon -- adequate exposure requires about 50 to 75 percent of your skin being exposed. That's a lot of exposed skin, and not feasible for a lot of people who live places where it gets cold for long stretches of time. Exposing less skin will still allow you to absorb UVB rays, but more time is required the less skin that's exposed.