Thanks very much for this question. It is true that if you are never exposed to the sun at all that you are going to have some trouble with vitamin D synthesis. But really all you need in order for this to happen is about 20-30mins of sun exposure in OFF PEAK time 2-3 times per week. So if you bear in mind that most of us only apply our sunscreens once a day (in the morning, to cover peak exposure time), by the time 3 or 4pm rolls around, you SPF is not really active any longer if you have not re-applied. So most people actually don’t have this problem. If you are one of those very dedicated people who does apply your sunblock twice a day… I am unfortunately one of those who is very deliberate about putting on my sunblock morning and again at lunch time, then just simply exposing part of your skin (your arms or legs or even the top of your back) just 2-3 times per week for about 20mins in off peak sun time will help you combat this issue.