Written by Dr. Baili Clarke, ND
You may know by now that vitamin D is good for you, but do you know why it is so good for you? Vitamin D is an essential fat-soluble vitamin (like vitamins A, E, & K), but it is unique in that our bodies can make it from exposure to sunlight and it functions as a pro-hormone (hormone precursor).
Worldwide, vitamin D3 (aka “cholecalciferol”) is obtained predominantly through exposure of our skin to UVB radiation from sunlight, and in very small amounts through the consumption of oily fish, egg yolks, beef liver, and fortified foods (i.e. milk, cheese, cereal, juice, margarine, etc.). Given our lack of exposure to sunlight throughout most of the year and the minimal amount present in foods, you can begin to see why vitamin D deficiency is so common for many Canadians and why supplementation is generally recommended. In fact, a comprehensive survey from 2007 to 2009 conducted by Statistics Canada, found that two-thirds of the population has vitamin D levels below the amount associated with reduced risk of chronic diseases, while one in 10 (more than three million people) have levels inadequate for good bone health. Besides latitude, other risk factors for vitamin D deficiency include: atmospheric pollution; being elderly or obese; having darker skin pigmentation; avoiding sunlight exposure (i.e. frequent sunscreen use); having a condition that causes malabsorption (such as Crohn’s disease, pancreatic insufficiency, small-intestinal bacterial overgrowth (SIBO), or a history of gastrointestinal surgery); taking medications that deplete vitamin D (such as anticonvulsants); and being an exclusively breastfed infant not receiving vitamin D supplements.
We now know that the benefits of vitamin D go well beyond regulating calcium and phosphorus levels in the body and supporting strong bones and teeth. Currently, there is evidence showing links between vitamin D deficiency and the development of conditions such as asthma, type II diabetes, depression, schizophrenia, high blood pressure, autoimmune diseases (i.e. multiple sclerosis, Crohn’s disease and type I diabetes), and cancer (primarily breast cancer, non-Hodgkin lymphoma, leukemia and colorectal cancer). Other manifestations of vitamin D deficiency may include chronic low back pain, diffuse aches and pains, unexplained fatigue and increased risk of falls. One group of investigators found that vitamin D deficiency can masquerade as fibromyalgia, depression, and chronic fatigue syndrome. Vitamin D can also play a significant role in the prevention of upper respiratory tract infections such as influenza (for more information on vitamin D and influenza click here). As you can see, having optimal levels of vitamin D is an important aspect of good health.So, how do you know if you have optimal levels? Luckily, vitamin D levels can be measured through a simple blood test ordered through your primary care physician. The stored form of vitamin D, 25(OH)D is the best test available to assess total vitamin D levels in the body and determine deficiency. The biologically active hormone form of vitamin D, 1,25(OH)2D (aka “Calcitriol”) can also be measured, but it is not recommended as a stand-alone test. Having a baseline assessment of your vitamin D levels is really the best way to optimize your supplementation dose and to avoid toxic levels. However, a daily dose of 1,000 to 2,000 IUs of vitamin D3 is the safe recommended dose for most Canadian adults to take long-term without testing. Exclusively breastfed infants require 400 IUs daily from birth, and children require 600 to 1000 IUs daily (depending on their body weight).The “sunshine vitamin” is not only important for supporting strong bones and teeth, but is an important factor in making sure your immune system, brain, heart, lungs, and muscles work optimally. Knowing your levels and supplementing appropriately are important actions for improving your overall health and well-being.
References:1. Gaby, A. (2011). Vitamin D. In Nutritional Medicine (pp. 108-117). Concord, NH: Fritz Perlberg Publishing.2. Vitamin D Council (n.d.). What is vitamin D. Retrieved from https://www.vitamindcouncil.org/about-vitamin-d/what-is-vitamin-d3. Kennel, K. A., Drake, M. T., and Hurley, D. L. (2010). Vitamin D Deficiency in Adults: When to test and How to Treat. Mayo Clinic Proceedings, 85(8):752-758. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2912737/4. Mittelstaedt, M. (2010, March 24). Statscan finds widespread vitamin D deficiency in Canadians. The Globe and Mail. Retrieved from http://www.theglobeandmail.com/life/health-and-fitness/statscan-finds-widespread-vitamin-d-deficiency-in-canadians/article596998/5. Statistics Canada (2010, March). Vitamin D status of Canadians as measured in the 2007 to 2009 Canadian Health Measures Survey. Retrieved from http://www.statcan.gc.ca/pub/82-003-x/2010001/article/11131-eng.pdf6. Vitamin D Council. (n.d.). How do I get the vitamin D my body needs. Retrieved from http://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs/#