Increase in use of high-dose vitamin D supplements. From 1999 through 2014 the number of US adults taking daily vitamin D supplements above the recommended levels increased, and 3 percent of the population exceeded the daily upper limit considered to possibly pose a risk of adverse effects, according to a study. Source 2k.
High doses of vitamin D rapidly reduce arterial stiffness in overweight/obese, vitamin-deficient African-Americans. In just four months, high-doses of vitamin D reduce arterial stiffness in young, overweight/obese, vitamin-deficient, but otherwise still healthy African-Americans, researchers say. Source 5l.
Vitamin D supplements are of no benefit to the over 70s. There is little benefit for those over 70 taking higher dose vitamin D supplements to improve their bone strength and reduce the risk of falls, new research has revealed. Source 3h.