“Although numerous studies have been promising, there are scant data from randomized clinical trials. Little is known about what the ideal level of vitamin D really is, whether raising it can improve health, and what potential side effects are caused by high doses,” the article states.
It adds that while there is some evidence to suggest vitamin D can benefit bones, immunity, diabetes, heart and kidney disease, high blood pressure and cancer, little of it is clinical.
Vitamin D supplement sales are estimated at about $250m in the US but the Times said the abundance of observational research was yet to clarify just how vitamin D benefitted health.
The article, ‘The Miracle of Vitamin D: Sound Science, or Hype?’, notes a study is being commissioned by US researchers with 20,000 elderly men and women to study vitamin D and omega-3 fatty acids.
Based on Institute of Medicine (IOM) recommendations, official daily intake levels from all food sources in the US and Canada sits at 200IU for under 50-year-olds; 400IU for 50-70-year-olds; and 600IU for those over 70.
In the wake of US Department of Agriculture data that shows about 70 percent of Americans are vitamin D deficient and upwards of 90 percent in Canada, the IOM is reviewing these levels, including safe upper levels some are expecting may rise to 10,000IU per day as opposed to the current level of 2000IU.