What is vitamin D?

Vitamin D is a fat-soluble vitamin that promotes calcium absorption in the gut. It maintains adequate blood calcium and phosphate concentrations to ensure normal mineralization of bone and prevent hypocalcemic tetany (spasms of the hands and feet and cramps due to low blood calcium). Vitamin D is also important for bone growth and bone remodeling. Without sufficient vitamin D, bones become thin, brittle and misshapen. Having sufficient vitamin D prevents rickets in children and osteomalacia in adults. In conjunction with calcium, vitamin D also protects older adults from osteoporosis.

Vitamin D also modulates cell growth, neuromuscular and immune function, and reduces inflammation1.

How much do I need?

For children and adults 9-70 years old, Health Canada recommends 600 IU (15 mcg)/day.

For adults older than 70 years old, Health Canada recommends 800 IU (20 mcg)/day2.

Am I getting enough vitamin D?

Although vitamin D can be produced through exposure to sunlight, many factors can reduce how much vitamin D your body makes, including:

  • smog
  • season
  • time of day
  • cloud cover
  • limited time outdoors
  • amount of skin exposed to sunlight
  • age – less vitamin D is made as you get older
  • colour of skin – people with darker skin absorb less UV rays3

In addition to the limitations of sun exposure for vitamin D production, there is also increasing public concerns about skin cancer due to UV radiation from the sun. Therefore, although we can meet some of our vitamin D needs through sunlight exposure, the intake of foods high in vitamin D is vital, along with the possible use of supplements2.

What foods are high in vitamin D?

Vitamin D is only naturally present in very few foods, but is also fortified in others, and is available as a dietary supplement. It is also synthesized in our bodies when our skin is exposed to UV rays from the sun.

Only a handful of foods naturally contain vitamin D and these include the flesh of fatty fish (e.g. salmon, tuna, and mackerel) and fish liver oils. From a plant-based perspective, some mushrooms also provide vitamin D, but in variable amounts. However, mushrooms can exhibit enhanced levels of vitamin D through exposure to UV light.

Luckily, some foods are also fortified with vitamin D, which enables us to obtain more vitamin D through our diet [1]. These foods include:

  • fortified non-dairy beverages, such as Silk unsweetened almond milk – 45% DV per 250 mL serving4
  • margarine such as vegan Becel – 40% DV per 2 tsp serving5

Do I need a vitamin D supplement?

At the moment, Health Canada recommends that if you are over 50 years old, you should be taking a daily vitamin D supplement of 400 IU.

If you are concerned about your vitamin D status and are wondering if a supplement is suitable for your needs, speak to your health care provider2.

References

  1. National Institutes of Health – Dietary Supplements. (2019, August 7). Vitamin D. Retrieved March 22, 2020, from https://ods-od-nih-gov.subzero.lib.uoguelph.ca/factsheets/VitaminD-HealthProfessional/
  2. Government of Canada. (2019, July 10). Vitamin D and Calcium: Updated Dietary Reference Intakes. Retrieved from https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/vitamins-minerals/vitamin-calcium-updated-dietary-reference-intakes-nutrition.html#a10
  3. Government of Canada. (2019, October 29). Vitamin D. Retrieved from https://www.canada.ca/en/health-canada/services/nutrients/vitamin-d.html
  4. White Wave Services Inc. (2020). Unsweetened Original Almond Beverage. Retrieved from https://www.drinksilk.ca/products/unsweetened-original-almond-beverage
  5. Upfield Canada Inc. (2020). Becel Vegan. Retrieved from https://www.becel.ca/en-ca/products/spreads/becel-vegan?gclid=Cj0KCQjwmdzzBRC7ARIsANdqRRnoSisaU5vHQ3kztL8wKHD05FW5iTCBq0Iv4lx5YGvqnx7Mn4CBCtYaAihnEALw_wcB

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