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 Click to share on Facebook (Opens in new window) Facebook Click to share on Reddit (Opens in new window) Reddit Click to share on X (Opens in new window) X Click to 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.