What about the need for obtaining vitamin D via the sun?
Most people can fulfill their vitamin D requirements of 600 IU or 15mcg per day with normal daily outdoor activities amounting to five to 30 minutes twice per week. Equally, a healthy vitamin D rich diet of fish, milk, dairy, liver, eggs and vitamin D supplementation provides daily requirements. Prolonged sun exposure gives no extra production of necessary vitamin D, and it exposes the skin to the harmful effects of ultraviolet radiation which includes development of skin cancers and photodamage.