By Dr. Sharon Orrange
Vitamin D is readily available through sun exposure and as a supplement yet there are new reasons to believe we are not getting as much Vitamin D as we need. Vitamin D deficiency can be discovered on a blood test done by your physician and is defined as serum 25-hydroxyvitamin D levels < 20 to 30 ng/mL. Depending on the age group and season we are looking at Vitamin D deficiency can affect 25% to 70% of people.
Why is Vitamin D important? Vitamin D affects not only bone health but deficiency of Vitamin D has been associated with increased risks for some types of cancer, cardiovascular disease, hypertension, musculoskeletal pain, and type 2 diabetes.
What has been learned from recently published Vitamin D studies?
1) A meta-analysis (analysis of a bunch of large studies already published) in the Archives of Internal Medicine 2007 [PubMed ID: 17846391] found that Vitamin D supplementation reduces mortality from all causes in adults and older individuals. These results suggest that for every 150 patients who received Vitamin D supplementation, 1 death was prevented.
2) Breast cancer has also been linked to low Vitamin D levels and pooled data from three trials found that the lower the vitamin D level the higher risk of breast cancer. This relationship was particularly true for people with Vitamin D levels < 20 ng/mL (Carcinogenesis 2008;29:93-9).
Who needs to be worry about Vitamin D deficiency? The elderly (especially those who don't spend much time outdoors), hospitalized patients, kidney patients, patients with GI illnesses or those who have had gastric bypass among others. What has surprised healthcare providers is that in healthy patients with enough sun exposure we are seeing Vitamin D deficiency. Its importance seems more apparent the more research we do.
How do we get Vitamin D? Very few foods contain Vitamin D with the exception of fatty fish and eggs. Fortified foods (foods where vitamin D is added) and the sun are the major sources. Briefly, vitamin D3 is synthesized in skin from exposure to ultraviolet rays in sunshine (cool, huh?). Vitamin D deficiency is caused by unusually low sun exposure combined with lack of vitamin D fortified foods OR malabsorption.
What's the take home message? Vitamin D supplementation is reasonable for people who have, or are at risk for, vitamin D deficiency. Current guidelines recommend 5 to 15 minutes of sun exposure at least twice weekly to the face, arms, hands, or back without sunscreen (yipes) and a daily vitamin D intake of 200 IU for persons 50 years, 400 IU for those 50 to 70 years, and 600 IU for those > 70 years. The new feeling is these recommendations may be too conservative and that daily intakes should be higher. As mentioned above, dietary sources rich in vitamin D are limited to fatty fish and some fortified foods, so the use of a vitamin D containing supplement is a good option. Many calcium supplements now contain vitamin D and I recommend these to my patients. Examples of Calcium + Vit D include: Caltrate, ColonHealth, Chew-Cal, Liqua-Cal, Os-Cal; and for Vitamin D alone, Calcitriol or Rocaltrol are popular options.