In the absence of sun exposure, vitamin D becomes an essential nutrient in the diet. There is particular concern in people over the age of 60 since they get less exposure to the sun and have poor dietary intake of vitamin D.
One simple strategy to prevent these problems and enhance health is to supplement with vitamin D. In an attempt to establish an effective dietary intake of vitamin D to bring blood levels up to acceptable limits, UK researchers performed a dose response study of increasing levels of vitamin D supplementation in men and women older than 64 years.
They concluded that an intake between 316 IU and 1,712 IU per day was required to bring the majority of people into a range of preferred vitamin D blood levels.