Vitamin D is a steroid hormone and a component of a complex endocrine pathway sometimes called 'vitamin D endocrine system' (Medscape, 2012). From Reuters:
Low levels of vitamin D may increase the risk of death in older adults, researchers reported in the Journal of the American Geriatrics Society.
Optimal vitamin D levels are considered to be between 80 and 120 nmol/L, although there are no set guidelines. On average, people in the current study had vitamin D levels of 66.0 nmol/L.
The risk of death was 47% higher among those with vitamin D levels between 25 and 49.9 nmol/L, relative to those with vitamin D levels of 100 or higher.
The risk of death due to heart disease was more than twofold higher in people with vitamin D levels lower than 25 nmol/L.
References:
Low vitamin D may be deadly for older adults. Reuters, 09/2009.
A vitamin D3 dosage of 800 IU/d increased serum 25-(OH)D levels to greater than 50 nmol/L in 97.5% of women http://bit.ly/GzBCcA
Image source: Wikipedia, public domain.
