Living in Southwest Florida, we definitely have our share of sunshine.  Standard sun prevention measures include hats, sunscreen etc.  But some new studies have revealed that taking 500 mg of nicotinamide twice daily can DECREASE the incidence of basal cell and squamous cell skin cancers by 25%.  There is some preliminary evidence it may prove equally effective in melanoma like skin cancers but further studies need to be done.  It is important to realize you need nicotinamide and not nicotinic acid.