Winter is fast approaching bringing with it the colder weather and darker days. Many of us in Canada will embrace the ice and snow to enjoy the sunshine and various outdoor activities. But regardless of our outdoor fun, over the winter months the lack of skin exposure to the sun and our position on the globe can promote vitamin D deficiency.
Some are lucky enough to get away to a sunny destination over the winter to replenish their vitamin D reserves. But for the rest of us who remain in the dark north, we can use up our stores of this important vitamin and become susceptible to lowered immunity and illness.
Vitamin D, otherwise known as the sunshine vitamin, is actually a steroid hormone that plays a crucial role in our bodies. It is produced by the action of the UVB rays on our skin. In fact our bodies can produce up to 10,000 IUs of vitamin D in 10 to 20 minutes of high sun if there is enough skin exposure on the arms, legs and torso. However, this is also dependent on the time of year, proximity to the equator and paleness of our skin colour. Dark-skinned individuals can take up to six times longer to reach these same levels and so are prone to vitamin D deficiency.
Unfortunately due to our increased awareness of skin cancer, and the subsequent enhanced use of sunscreen, we are often no longer producing optimal vitamin D levels during the summer months. Recently a Statistics Canada study supported this when it reported that more than 32 per cent of the population has lower than optimal vitamin D levels.
This crucial hormone is important for many bodily functions, such as assistance with the regulation of calcium levels in your blood, keeping your bones and teeth strong, supporting healthy immune function, helping to prevent inflammation, and assisting with cell regulation. There have been many significant studies published over the years pointing to its relevance in breast cancer prevention, including a recent promising study published in the scientific journal Nature.
Vitamin D can be provided in smaller quantities through foods such as salmon, shrimp, sardines, cod liver oil, eggs, some varieties of mushrooms, and in fortified grain and milk products. But food alone is often not enough to provide ample vitamin D for most of us, so supplementation should be considered for many, especially over the winter months.
The Canadian Cancer Society recommends 1,000 IU of vitamin D to be taken during the fall and winter and suggests that those who are deficient in vitamin D should take the same dose year round. Health Canada advises that adults take 600 IU daily for health and furthermore Osteoporosis Canada recommends that adults take 400 to 1,000 IU daily.
So what is the right dose? Well, that depends. Every individual is unique and will absorb supplemental vitamin D at different levels. Factors that can effect vitamin D assimilation include types of foods eaten, availability of vitamins or minerals in the blood, and overall state of health. Optimum doses of vitamin D vary considerably from person to person and can range anywhere from 600 IU to 10,000 IU daily, depending on the above criteria.
It is important to know your present vitamin D levels so that you can determine a dosage that is right for you. To identify your vitamin D status, I recommend that everyone book an appointment with their doctor to check their serum 25(OH) D3 number. This test is no longer covered under OHIP for most individuals (unless there is a predetermined health concern such as osteoporosis) and can cost anywhere between $30 and $50 depending on the lab.
If it is determined that your serum vitamin D is below the optimal levels of 100-150 nmol/L, consult with your health care professional to determine the right dosage for you and follow up with another test two to three months later to see how your vitamin D dosage is faring.
Sheila Ream, CNP is a certified nutritionist in the Beach ~ shealaream@sympatico.ca
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