Zealous advertisers advocate sunscreen products with sun protection factors (SPFs) ranging from 15 to 100+. But how much of this is scientifically validated, and how much is spin-doctoring taking advantage of fearful and gullible consumers? Is an SPF of 100 really twice as good as one of 50, or even 30 or 15 for that matter? The short answer is no. The numbers do not compute that simply, as we will see.
Calcium is the principal mineral in bone, and if you don’t get enough calcium you either can’t make enough bone during growth or you tear down your bone as an adult in order to make up for what your diet doesn’t provide. Now vitamin D comes into the story, because vitamin D is necessary to help the body regulate calcium absorption so that you use your food calcium with maximum efficiency.