"Who Cares about Vitamin D"
WHO CARES ABOUT VITAMIN D? By: Bryn Sharkey Summer Work Program – May to August 2008 Ste. Rose du Lac, Manitoba Supervisor: Dr. David O’Hagan Who Cares About Vitamin D? Bryn Sharkey It has been known for almost a century that Vitamin D is critical to bone development. Recent research suggests that vitamin D may have a much larger function in healthy development and disease prevention. Furthermore, there is increasing concern that vitamin D deficiency may be far more prevalent than previously anticipated. Vitamin D is a fat-soluble vitamin that can be acquired through both diet and sunlight. It is found naturally in very few foods but there are small amounts in cheese, fish (salmon, tuna, mackerel) and egg yolks. Health Canada has made supplementation mandatory in milk, margarine and other butter substitutes. Producers supplement voluntarily in some breakfast cereals, yogurts and orange juices (1,2). Unfortunately, those living above 35 degrees latitude, which lies approximately around Atlanta, Georgia, are unlikely to acquire enough sunlight at certain times of the year for adequate vitamin D production (3). This is due to the oblique angle of the sun in fall and winter months as well as during the early morning and evening hours. Thus it is not surprising that vitamin D deficiency is a concern, especially for those living at higher latitudes. A study published in CMAJ in 2002 from the University of Calgary estimated vitamin D deficiency (serum levels <40nmol/L) in western Canadians to be greater than 34%, while a recent clinical review published in May 2007 in the Canadian Family Physician found levels of vitamin D deficiency in Canadians to be as high as 97% in the fall and winter months (4,5). Because the levels of deficiency vary between different demographics, and because a universally accepted level for vitamin D deficiency has yet to be established, it is difficult to determine an exact proportion of the population which may be at risk. Page 2 of 10 Who Cares About Vitamin D? Bryn Sharkey Vitamin D deficiency can result from inadequate exposure to UVB rays from sunlight, insufficient dietary intake, impaired absorption or increased requirements which are not met over time(1). Vitamin D deficient diets are often associated with those who are vegans or have milk allergies or lactose intolerance. However, several other populations are also at risk. A 2000-2004 study as part of the NHANES (National Health and Nutrition Examination Survey) revealed groups specifically at risk to be females, those who are obese, and those with pigmented skin (1,6). The study found the prevalence of vitamin D deficiency (serum 25-hydroxyvitamin D <25 ng/mL) among African Americans to be ten times greater than the deficiency among Caucasians. The survey however, was not designed to assess whether the deficiency had any impact on health. A 2003 report from Memphis revealed that twenty of the twenty-one cases of rickets reported that year occurred in children of African-American descent (1). Other groups reported to be at risk of vitamin D deficiency include exclusively breastfed infants, as their mothers may be lacking in the vitamin, those with limited sun exposure such as housebound individuals, those at northern latitudes, those who remain covered by clothing or head coverings for religious or personal reasons, and those whose occupation prevents them from sun exposure during the peak hours of the day. The increasing use of sunscreen may be a significant contributor to Vitamin D deficiency. Older adults are at a particular risk as both the skin and the kidney have a decreased ability to synthesize the active form of vitamin D. People with a compromised ability to digest and absorb dietary fats such as in pancreatic enzyme deficiency, Crohn’s disease, cystic fibrosis, surgical removal of parts of stomach or intestines, or with some forms of liver disease are also at risk of deficiency (1,3,). Page 3 of 10 Who Cares About Vitamin D? Bryn Sharkey In the 1920’s, vitamin D deficiency was found to be the cause of rickets and osteomalacia (1). This finding has significantly reduced the incidence of rickets in the developed world. Apart from its well-known role in promoting calcium absorption in the gut to assist in bone mineralization and growth, vitamin D has been proposed to have additional potential benefits. Other roles of vitamin D include contribution to neuromuscular and immune function, through the activation of mast cells and the potential to decrease inflammation (1). Several genes involving proteins that function in cell proliferation and differentiation are modified in part by vitamin D which prompted recent research suggesting a role for vitamin D in the prevention of breast, colorectal and prostate cancers (3). An ever enlarging body of research suggests vitamin D may help prevent type 1 and type 2 diabetes, hypertension and multiple sclerosis (1,3,7). Most of these studies however, were animal or epidemiologically based, and not randomized controlled trials. When UVB photons from sunlight are absorbed into the skin, 7-dehydrocholesterol is transformed into previtamin D3, which is then converted to an inactive form of vitamin D with the aid of heat. The compound then diffuses into the capillary beds and is transformed by the liver into 25 hydroxycholecalciferol (25(OH)D3), and the kidney into its active form 1, 25(OH)2 D3 (3). For most individuals, only 5-15 minutes of unprotected sun exposure to the arm and face during the spring and summer is required to obtain 100% of the daily dose of vitamin D. However, excessive sun exposure cannot cause toxicity, due to photodegradation of pre vitamin D3 (1). Thus vitamin D toxicity is unlikely and would have to result from a constant overdose of vitamin D supplements over a long period of time (doses of 50 000 IU(International units)/day for eight weeks Page 4 of 10 Who Cares About Vitamin D? Bryn Sharkey were not shown to cause toxicity). It has been thought that vitamin D toxicity has the potential to cause nausea, vomiting, constipation and increased blood calcium levels which may lead to mental status changes, cardiac rhythm abnormalities and kidney stones(1). One study has shown no toxicity at 10 000 IU of vitamin D, although this study was not adequately addressed to assess harm (1). Despite the growing body of evidence that requirements for Vitamin D are greater than previously thought, Health Canada has yet to update its current 400 IU (International Units)/day RDI (recommended daily intake), which was suggested in 1997 solely for the prevention of rickets (3,8). Now many experts believe 1000 IU/day is necessary to maintain adequate serum blood levels of vitamin D (>30mg/mL). Recently, the Osteoporosis Society of Canada recommended all adults should consume at least 800 IU/day (9). The Canadian Cancer Society recommends all adults should consume 1000 IU/day, and breast fed infants should get 400 IU/day, especially during fall and winter months (October to March) (8). For the elderly, those with dark skin, or those who stay indoors or who wear clothing to completely cover skin, supplementation is recommended year round. The Canadian Cancer society recommends a few minutes of unprotected sun exposure per day, while it has not changed its guidelines for skin cancer prevention. In response to the recent publicity, Health Canada plans to launch a study in the fall of 2008 to investigate claims that lack of vitamin D could lead to ailments such as cancer, heart disease, and multiple sclerosis. There is rising pressure from the Canadian Cancer Society and Canadian Pediatric Society to increase the recommended daily intake of vitamin D because they believe the evidence warrants RDIs 5-10x higher than the current recommendation (1,2,10). Developing a new recommended daily intake in North Page 5 of 10 Who Cares About Vitamin D? Bryn Sharkey America will prove difficult, due to the variation of susceptibility among different populations, including geographic location, age and skin pigmentation. To investigate the current awareness of vitamin D in the community of Ste. Rose du Lac, MB, I surveyed 75 clinic patients on June 24, 25, and 26, 2008. The patient population included both those with scheduled appointments and walk in visits. Ste. Rose is a farming-based community, which also services several aboriginal reserves in the surrounding area. My objectives were to assess awareness about vitamin D supplementation, both the benefits and suggested doses, assess sun exposure, ask about sources of health information and assess barriers people face to obtaining adequate vitamin D. Without measuring the serum vitamin D levels, I hoped to make an estimate of the potential for vitamin D deficiency based on diet, supplementation and sun exposure. Given the demographic, I expected copious sun exposure in the spring and summer months, but a potential for vitamin D deficiency in the fall and winter due to our northern latitude. I also expected a lack of awareness about current vitamin D benefits and recommendations, due primarily to the discrepancies in recommendations among various health organizations, and the barriers to publicizing a consistent recommended daily intake of vitamin D. By the new standards set by the Canadian Cancer Society (1000IU/day), 93% of study patients did not obtain adequate vitamin D intake year round (based on diet, sun exposure and supplementation). According to the current Food and Drug Regulations (FDR) guidelines (400IU/day), 73% were not obtaining adequate levels. As expected, the Page 6 of 10 Who Cares About Vitamin D? Bryn Sharkey estimated levels of deficiency varied widely with the seasons, with only 4% of people being deficient in the spring and summer months. Eighty-five per cent of study participants were unaware of any benefits of vitamin D, and only 10% knew about benefits to bones. Sixty per cent stated that their primary source of health information was from a health professional. Thirty-five per cent expressed that no barriers prevented them from supplementing with vitamin D, and 36% stated that it was a lack of awareness of the benefits, which prevented them from supplementing their diets. I have concluded from this study, that the potential for Vitamin D deficiency during the fall and winter months is significant in this population, and these results could be reasonably extrapolated to other northern communities. Moreover, the main barrier to lack of this vitamin is a simple lack of awareness rather than lack of opportunity. As primary prevention may be the most effective method to improve the health of the population, health professionals should consider taking every opportunity to educate their patients on nutritional status. As new research confirms further benefits of vitamin D and allows us to reach a more definitive conclusion on the appropriate amount required for good health, doctors and other health professionals will be more confident in informing the public about supplementation. Page 7 of 10 Who Cares About Vitamin D? Bryn Sharkey Vitamin D Survey _____________________________________________________________________ 1) Do you take any nutritional supplements? Yes/No (Circle one) If yes…. a) Vit A ___ Vit B___ Vit C ___ Vit D ____ Vit E ____ Multivitamin ___ Calcium ___Other____ If vitamin D supplement taken... Question 2+3 2)) what dose? 10mcg/400UI____ 25mcg/1000IU ____ unknown_____ other ____ 3) Do you take it seasonally? Winter____ spring ___ summer _____ fall____ If vit D supplements NOT taken… Question 4 4) How do you get your vitamin D? milk (amount in cups) ________ sun exposure _____other ____ 5) Are you aware of the health benefits of vit D? Support bone growth ____ immune function ____ reduce inflammation ____ cancer prevention___ other _____ none____ 6) From what source do you get most information about health? TV ____ Newspaper ____ Magazines ____ Internet _____ word of mouth _____ Health Professional _____ Other _____ 7) If not taking vitamin D why not? Cost ____ not aware of benefits ____ sufficient amount in diet____ other ___ none____ 8) How many minutes of unprotected sun exposure do you get per day during the spring and summer? None____ 5 min ____10min____15min_____20 min____25 min____ >/=30 min_____ - Age: Sex: M/F (Circle one) Page 8 of 10 Who Cares About Vitamin D? Bryn Sharkey References: 1. Dietary Supplement Fact Sheet: Vitamin D. National Institute of Health: Office of Dietary Supplements; c2008 [2008 May 16;cited 2008 June 15]. Available from: http://ods.od.nih.gov/factsheets/vitamind.asp 2. Food and Drug Regulations. Health Canada. 2004 June. Division 8; B.08.003. Available at: http://www.hc-sc.gc.ca/fn-an/alt_formats/hpfb-dgpsa/pdf/legislation/e_f- vtamns.pdf 3. Holick MF, Chen TC, Lu Z, Sauter E, et al. Vitamin D and Skin Physiology: A D- Lightful Story. J Bone and Mineral Res. 2007;22:V28-33. 4. Rucker D, Allan JA, Fick GH, Hanley DA et al. Vitamin D insufficiency in a population of healthy western Canadians. CMAJ. 2002 June 11; 166(12). 5. Schwalfenberg G. Not enough vitamin D. Canadian Family Physician. 2007 May 5;53:841-854. 6. Prentice A. Vitamin D deficiency: a global perspective. Nutr Rev. In press. 7. U.S Department of Agriculture. Nutrient Data Laboratory. Search the USDA National Nutrient Database for standard reference. Available at http://www.nal.usda.gov.fnib/foodcomp/search 8. www.cancer.ca [homepage on the internet]. Vitamin D. Canadian Cancer Society. 2008 June 8. [cited 2008 June 20] Available at: http://www.cancer.ca/ccs/internet/standard/0,3182,3172_1176359459__langId- Page 9 of 10 en,00.html Who Cares About Vitamin D? Bryn Sharkey 9. Vitamin D: A key factor in Calcium absorption. Osteoporosis Society of Canada. 2007. Available at: http://www.cancer.ca/ccs/internet/standard/0,3182,3172_1176359459__langId- en,00.html 10. Mittlestaedt M. Canada orders vitamin D study. The Globe and Mail. 2008 May 10. Available at: http://www.theglobeandmail.com/servlet/story/RTGAM.20080510.vitamin10/BNStory/N ational/ Page 10 of 10