According to the winter ’12-’13 edition of Life Extension, even people who are taking vitamin D supplements are deficient in this important vitamin.
Many people think that getting 400 to 600 I.U. in their multivitamin is enough. It’s not, especially if you are older.
“Aging persons need to supplement with about 5,000 I.U. of vitamin D each day to achieve optimal blood levels. This is about 10 times more than the typical American takes.” You should also take the majority of that dose with the meal that contains the most fat to get maximum absorption. That’s the last meal of the day for most people.