The dark days are coming. After enjoying the seemingly endless, warm, sunny days of summer, we’re once again forced to accept the swift arrival of autumn. While the cool, fresh breezes and multi-coloured foliage that come with the season are certainly beautiful in their own right, the reality is that each passing day gives us less and less daylight with which to actually appreciate all those vibrant orange and red leaves. For those of us living in the Northwest, the veil of dark, gray rain clouds accompanying these increasingly brief daylight hours only compound matters further. And while most of us see the coming months of near-darkness as something to be endured rather than savoured, perhaps nothing suffers as greatly during this time as our vitamin D levels.
When exposed to the ultraviolet-B (UVB) radiation in sunlight, our skin’s outer layer (the epidermis) converts a steroid compound called 7-dehydrocholesterol to vitamin D3. The vitamin D3 then enters the bloodstream, where it is undergoes modifications first in the liver and then in the kidneys. At this point, the nutrient is most able to perform its vast array of functions, including aiding in calcium absorption and supporting bone density, optimizing immune function, and regulating mood. Unfortunately, as the number of daylight hours decreases (in Vancouver, from roughly 16 hours per day mid-June to 8 hours per day mid-December), this entire process can become strained, increasing the risk of vitamin D deficiency. Add in the inevitable fact that what little winter sunshine we’ll be seeing in B.C. will be largely masked by a mass of cloud cover, and the situation grows more dire still.
Of course, it is certainly possible to obtain sufficient amounts of vitamin D from one’s diet (including fish such as salmon and mackerel, eggs, and dairy products), but for many individuals, factors such as dietary restrictions and absorption issues can make this difficult. For most, if not all people, it is often prudent to check one’s actual vitamin D status to see if supplementation is warranted. A simple blood test to examine the 25-hydroxyvitamin D level will quickly answer that question, though a recent study concluded that over 75% of adults and teens in the U.S. exhibited vitamin D deficiency. Luckily, there’s a fast, easy and cost-effective remedy to the problem—a high quality, appropriately-dosed vitamin D3 supplement can go a long way towards staying strong, healthy and happy through the long, dark months ahead.
Ginde AA, Liu MC, Camargo CA. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med. 2009;169(6):626-32.
