Here is part of the story.  Although research had been on-going for many years, a 2007 medical journal article drew new attention to Vitamin D. The report by Dr. Michael Holick, an endocrinologist and Vitamin D researcher, pointed to many more possible roles for Vitamin D beyond its function in preventing rickets, a Vitamin D deficiency causing bowed legs and poor bone mineralization (N Engl J Med 2007, 357:266-81). This report along with others, presented very exciting correlational data showing that higher blood levels of Vitamin D and increased sun exposure had been correlated with decreased risks of rheumatoid arthritis, heart disease, depression, cancer, falls and bone fractures and improved cognitive function and muscle strength. The emerging evidence suggested that the recommended daily intake was inadequate to improve low blood levels and that the accepted blood levels were probably below ideal for health (though they seemed to prevent rickets). Low vitamin D levels seemed like a real answer to many chronic health problems and many researchers felt that significant increases in recommended intakes were warranted.

Dr. Holick’s work (and others) had suggested that Vitamin D deficiency is the most common medical problem worldwide. He calculated that having “sufficient” blood Vitamin D levels could reduce the risk of having a first heart attack by nearly 50%, reduce the risk of developing peripheral vascular disease by as much as 80%, and also might reduce the risk of developing cancers such as prostate, colon, and breast by as much as 50%-70%. Additionally, Dr. Holick believes that Vitamin D deficiency may increase risk of developing Type 2 Diabetes and that by increasing Vitamin D intake to about 800 international units (IU) per day, the risk of developing Type 2 Diabetes may be reduced by as much as a third.

Despite all this suggestive correlational data, after a thorough review of the literature, the 2010 Dietary Guidelines Vitamin D review committee concluded that evidence of Vitamin D’s role in anything other than bone health had not been sufficiently researched and that the mechanisms of action in other physiological functions, though scientifically plausible, had not been thoroughly elucidated and proven. Further, they stated that there was no evidence of widespread deficiency in the U.S. The committee’s final recommendations, considered levels at which rickets could be prevented and maximum bone density could be achieved and the level necessary to help prevent osteoporosis. They did increase the recommended intakes, but only slightly and they did increase the Tolerable Upper Intake Level (UL) – the upper limit for safe daily intake.

Research has continued and many scientists believe that recommended levels of intake will be increased after more studies are completed. Work in 2010 included prospective studies and controlled experimental studies showing less cognitive decline in brain function in individuals with higher blood Vitamin D levels and improved insulin sensitivity and blood sugar control in people supplemented with Vitamin D. Many additional studies are currently underway to examine vitamin D’s role in preventing and treating disease.

So what should Alaskans do? First, understand that the Dietary Guidelines are designed for “population wide” recommendations. What an individual does should be based on individual assessment of risks and needs. The human body normally produces Vitamin D when the skin is exposed to sunlight. Living in Alaska with limited sun exposure, puts many of us at risk for deficiency. There is evidence from some communities in Alaska that as many as 50% - 60% of apparently healthy, adults are deficient.

Adults should have Vitamin D levels checked. This may be especially important for older individuals, who are at greater risk of insufficient levels. Many community health fairs offer low cost Vitamin D screenings or your medical provider can include this in your routine blood work. Be sure to ask your medical provider whether supplementation is appropriate – I’ve talked to many people who have had Vitamin D levels checked but did not have follow-up to interpret the results. If your blood levels are low, take appropriate supplemental amounts to attain a healthy blood level and include more foods with Vitamin D in your daily diet.  

Vitamin D supplements are not expensive and easy to take. When determining the appropriate supplementation level, consider how much you get from foods that you eat and supplements you take such as calcium with Vitamin D and multi-vitamins containing Vitamin D. If you are not deficient, refer to the Recommended Dietary Allowances for suggested safe daily intake levels.

These tables are adapted from the following two sources. For more information you may want to read the report entitled Dietary Reference Intakes for Calcium and Vitamin D ( www.iom.edu/Reports/2010/Dietary-refernce-Intakes-for-Calcium-and-Vitamin-D.aspx) or the Office of Dietary Supplements Vitamin D Fact Sheet ( www.ods.od.nih.gov/factsheet/vitamind ).