SUNLIGHT IS GENERALLY SUFFICIENT. “Although the amount of vitamin D adults get from their diet is often less than what’s recommended, exposure to sunlight can make up for the difference.” Except if obese, taking drugs that interfere, or with other medical conditions.
http://www.mayoclinic.org/healthy-living/nutrition-and-healthy-eating/expert-answers/vitamin-d-deficiency/faq-20058397