Feature Health & Medicine Vitamin D: What’s Enough? Many people may need much more By Janet Raloff October 12, 2004 at 5:39 pm - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Print (Opens in new window) Print Second in a two-part series. Part I: “Vitamin Boost” is available at Vitamin Boost. UNDEREXPOSED. At low sun angles, as here, little ultraviolet energy is available for making vitamin D. PhotoDisc A few minutes of sun exposure on a summer day can generate huge quantities of vitamin D in a person’s body.