Sunlight is at a premium these dreary days. After a long-cold winter, the anticipation of sunny summer afternoons occupies a special place in Canadian minds. Along with the emotional longing for some rays, long, dark winters leave us with some physiological needs as well – namely widespread vitamin D deficiency.
As the cycle of health news goes, vitamin D is taking its turn in the spotlight (or sunlight?) this month. A recent letter in the journal Nutrients revisited several findings, including those from Alberta School of Public Health researcher Dr. Paul Veugelers, claiming Vitamin D requirements are underestimated – possibly by a factor of 10.
Currently, health Canada recommends daily Vitamin D supplementation of 600-800 IU per day (the same as our neighbours to the south). Recent research suggests that 7,000 IU per day is a more accurate requirement. That is a startling discrepancy with serious health consequences.
There is significant evidence that vitamin D deficiency is correlated with increased risk of diabetes, depression, cancer, cardiovascular disease, multiple sclerosis, osteoporosis, and a growing list of serious chronic diseases.
Deficiency is a particular issue in Canada, as the farther individuals live from the equator the more likely they are to have inadequate Vitamin D levels. In Canada, it is estimated that two thirds of individuals have vitamin D levels below the threshold associated with decreased risk of chronic disease.
But is there too much of a good thing? As it turns out, probably. It is generally agreed that dosing up to 10,000 IU per day is safe. Large doses, up to 50,000 IU, may be used on a short-term basis to correct deficiency – but research suggests long-term dosing at this level may raise vitamin D to an unsafe level.
Danish researchers recently concluded that there is a sweet spot for vitamin D levels, between 50 and 100 nanomols per litre. In the study, individuals with elevated vitamin D levels showed an increased risk of cardiovascular events. With research on cancer prevention suggesting Vitamin D levels over 90 as the most protective, there is strong evidence to support maintaining a level in the sweet spot.
It is clear that optimal vitamin D levels are crucial to chronic disease risk reduction. Unfortunately testing is not covered under the Ontario Health Insurance Plan unless individuals meet specific risk-based or diagnostic criteria, but patients can pay out of pocket for the test. While no form of supplementation can replace a healthy diet and activity levels, it is clear that taking the simple step to optimize vitamin D levels can play a significant role in chronic disease risk reduction.
