There seems to be a lot of hype these days about Vitamin D supplements. Debates continue on about its role in preventative health, and about how much we should consume. Some suggest that Vitamin D is the cure for asthma, rheumatoid arthritis, multiple sclerosis, and even diabetes and cancer. Research is still unclear on the benefits in chronic disease prevention, it is without a doubt an important nutrient and we know that deficiency can cause rickets and weak bones. Vitamin D increases the amount of calcium you absorb, and it is very important for your bone health. In Canada, the current recommendation of Dietitians and Health Canada is 600 international units (15 micrograms) a day for ages 1-70 and 800 units (20 micrograms) a day for ages 71 and older. The majority of Canadians do not consume enough Vitamin D through food sources.
Some common and uncommon sources of Vitamin D are noted below.
1) The sun – Our body naturally has the ability to produce Vitamin D with sun exposure. The UVB rays in the sun convert a Vitamin D precursor (7-dehydrocholesterol, made from cholesterol by the liver) in our skin to the active form of vitamin D3. However, the process doesn’t provide us with enough vitamin D to meet the current recommendations from the months from October to March at northern latitudes. The amount of sunlight in the sky is simply not enough to produce adequate Vitamin D, even if you are outdoors all day. Also, if you are a dark skinned person, you will not make as much Vitamin D as a light skinned person. This is because your skin naturally produces much more melanin, a dark brown pigment that acts as a natural sunscreen and blocks out the UVB radiation. You can determine your skin colour type by using the Fitzpatrick scale. (link) If you are very pale, you are very efficient at making Vitamin D from the sun, however, it might be dangerous for you to stay out in the sun for a long time in view of an increased risk of sunburns. People who remain indoors for most of the day or wear clothing that covers most of the skin typically don’t their recommendations through sun alone. Wearing sunscreen is a great idea, but keep in mind that it doesn’t allow for maximum production of vitamin D.
2) Milk – In Canada it is mandatory for cow’s milk to be fortified with Vitamin D, so you can always expect to get around 100 international units in each cup (250mL) of commercial cow’s milk sold in Canada.
3) Fortified plant-based beverages. Almond, hemp, cashew, soy, rice, quinoa, and other plant-based beverages must be fortified with Vitamin D if they are marketed to be a milk substitute. You can expect to get around 80 to 100 international units per cup.
4) Dairy products and products made with fortified plant beverage – Although they don’t contain as much vitamin D as milk and plant-based beverages, many dairy products, like yogurt and cheese, are made with Vitamin-D-fortified milk. They are not considered a “significant source of” Vitamin D but do provide some vitamin D.
5) Fish, eggs, and organ meats – There are a few foods that naturally contain Vitamin D. Fatty fish like salmon, trout, and sardines, as well as egg yolks, organ meats (kidney and liver) and red meat have a substantial amount of vitamin D.
6) Irradiated mushrooms – Mushrooms are an abundant source of Vitamin D1 (ergosterol), a less active form of Vitamin D, but upon sun exposure, the UV rays convert Vitamin D1 to Vitamin D2 (ergocalciferol), which is much more active and counts as to have equal potency as Vitamin D3! For example, fresh Shiitake mushrooms have around 100IU VitD/100g, but sun-dried Shittake mushrooms soar in Vitamin D levels, it has around 1600IU/100g. Sun-dried mushrooms also have an enhanced umami flavor and add a great depth of taste to dishes.
7) Vitamin D supplements – Canada’s food guide recommends adults over 50 to take a daily Vitamin D supplement of 400 International Units (10 micrograms), or if you are vegan and do not drink milk alternatives, if you are dark-skinned, or if you are pale-skinned and cannot get enough sun exposure. Since the recommendations have been slowly but gradually increasing over the past few decades, and a lot of my clients are at risk for D-deficiency, I generally recommend that my clients take 1000 to 2000 International Units a day, especially in the winter months.
1. Health Canada. (2012, March 22). Vitamin D and Calcium: Updated Dietary Reference Intakes. Retrieved May 17, 2015, from http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php#a10
3. HealthLink BC. (2014, August). Food sources of calcium and vitamin D [Fact sheet]. Retrieved May 17, 2015, from http://www.healthlinkbc.ca/healthfiles/hfile68e.stm
4. Holick, M. F. (2008). Vitamin D and sunlight: Strategies for cancer prevention and other health benefits. Clinical Journal of the American Society of Nephrology, 3(5), 1548-1554. http://dx.doi.org/10.2215/CJN.01350308
5. Mushrooms Canada. (n.d.). Mushrooms & vitamin D. Retrieved May 17, 2015, from Mushrooms Canada website: http:/www.mushrooms.ca/nutrition/vitamins.aspx
6. Schmid, A., & Walther, B. (2013). Natural vitamin D content in animal products. Advances in Nutrition, 4, 453-462. http://dx.doi.org/10.3945/an.113.003780
7. Urbain, P., Singler, F., Ihorst, G., Biesalski, H. S.-K., & Bertz, H. (2011). Bioavailability of vitamin D2 from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: A randomized controlled trial. European Journal of Clinical Nutrition, 65, 965-971. http://dx.doi.org/10.1038/ejcn.2011.53