Vitamin D- the new wonder drug??

The September issue of The American Journal of Medicine (Volume 122, Issue 9) has an extensive review of the research on the benefits of Vitamin D. The article notes that over 1/2 of the world's population is Vitamin D deficient. We used to think that Vitamin D was only important for healthy bones but recent research has shown that Vitamin D affects our health in many other ways.
Vitamin D is important in bone health- one study showed that given 800iu/d of Vit D- persons aged 65-85 years of age had 1/3 reduced fracture risk.
Vitamin D is also needed for muscle development and function- one study has shown a 22% decrease in falls related to improved neuromuscular function with Vitamin D supplementation. Vitamin D is found to decrease muscle degeneration and increase reaction time and motor response which also decreases fall and therefore fracture risk.
Vitamin D has also been linked to chronic pain. Numerous studies have tied low levels of vitamin D to persistent musculoskeletal and neuropathic pain. Persons with chronic pain that has no obvious cause should be tested vitamin D deficiency.
Vitamin D is involved in the immune response and autoimmune diseases. Research has found a 40% lower risk of multiple sclerosis in women taking vitamin D supplements. Lupus and rheumatoid arthritis symptoms are more severe in those who are vitamin D deficient.
It seems that Vitamin D influences insulin sensitivity and beta cell function as well. Up to a 60% increase in insulin sensitivity was found in persons with greater than 30ng/ml serum vitamin D levels compared with those that have less than 10ng/ml. One study showed an 80% decreased risk of developing diabetes type 1 in children supplemented with 2000 iu/d of vitamin D in the first year of life. These children were followed for 20 years.
It appears that vitamin D is also involved in brain function. Older adults with low vitamin D levels performed worse on the mini mental status exam and showed more memory problems and depression than those with normal vitamin D levels. One large study found a correlation with depression severity and low vitamin D levels.
Some studies show a decrease in cancer risk and mortality associated with vitamin D. Vitamin D has been found to be antiproliferative, promote cell differentiation, and induce apoptosis, among other anti-cancer properties. Numerous studies have shown benefit in prevention and mortality in colorectal cancer, pharyngeal cancer and leukemia, as well as decreased breast cancer risk and decreased mortality from melanoma.
There is evidence that vitamin D has a role in cardiovascular health. Vitamin D is thought to influence the reticular activating system, vascular calcification, smooth muscle proliferation, and inflammation. Studies suggest that vitamin D deficency is an independent risk factor for myocardial infarction in men. Higher vitamin D levels are shown to decrease vascular calcification. Due to it's potent effect on vascular endothelial cells- vitamin D can lower blood pressure. It also seems to have a role in preventing cardiomyopathy- at least in hemodialysis patients.
All cause mortality is decreased by at least 7% in a meta-analysis of 18 randomized trials of vitamin D supplementation.
What do we do now?
Serum Vitamin D levels can by checked by ordering a 25(OH)D serum analysis. A result of 30ng/ml is considered normal although due to variations in laboratory results the current recommendation is to aim for 35-40ng/ml as an optimum level. Some suggest that all individuals be screened for vitamin D levels.
While we synthesize vitamin D from sun exposure- it is not recommended due to skin cancer risk and photoaging effects on the skin. Oral supplementation in the form of vitamin D3 is most effective. While dosage recommendations vary- from 200IU per day and up- it is safe to take larger doses- so1000-3000IU/d may be recommended in the near future.
Clearly there is overwhelming evidence that vitamin D deficiency is widespread and that suppplementation is inexpensive and highly beneficial. For more information refer to the original article and the 108 references that accompany it.