Hallowe'en reminds me to turn back the clock and dig out the snow shovel from the storage shed. Morning skies become darker and before I know it, the only sun I will feel on my face is occasional weekends at the ski hill or a well timed midday jog on a south of the border business trip. Time to reach for the sunshine in a bottle, and no, I don't mean the self tanner left over from last year's Cancun vacation. Vitamin D is in the headlines, enjoying its own day in the sun, and for good reason.
The industrial revolution has led us indoors and the digital age has kept us there, in front of our Wiis and laptops. Sunscreen and northern climes contribute even more to a potential vitamin D deficiency scenario. For decades, Vitamin D has been included in multivitamin supplements, but at a level (400 IU) that many researchers and scientists now feel may be below optimal. Why? Because new research shows that many body tissues have receptors for vitamin D and getting sufficient levels of it could substantially reduce the risk for breast, colon, prostate and ovarian cancers (2005 Study - American Journal of Public Health). Some smaller studies theorize that vitamin D has cardiovascular benefits and may help protect against some autoimmune conditions. In fact, recent research suggests that vitamin D may be just as important at helping prevent that winter cold and flu as vitamin C, due to its importance in the regulation of Th1 cells, an important group of immune cells. And we already know how vital vitamin D is in helping the body to absorb calcium to build strong bones and muscles and prevent osteoporosis.
Vitamin D is a hormone initially manufactured in the epidermis by exposure to ultraviolet B rays. Unfortunately, other than getting 10 to 15 minutes of sunshine three times a week (without sunscreen), it is difficult to get sufficient amounts from our typical north American diets. It does not occur naturally in most foods (no, not even milk - it is an additive.) Fish high in fat and fatty acids, like salmon, tuna and mackerel all contain vitamin D but unless you are having sushi for lunch everyday, you are likely not getting your share. Vitamin D supplements are relatively inexpensive compared to other vitamins and supplements and can be obtained in liquid or tablet form.
So, how much is enough? Well, there is a cry from some medical and research communities to raise the daily recommended value from 400 IUs to 800 or even 1,000 IUs in order to experience the greatest benefit. The National Academy of Sciences has set 2,000 IU daily as the tolerable upper limit. Vitamin D can have some food and drug interactions. Check with your physician to get the best advice for you and don't jump on the bandwagon if you are taking antacids and magnesium or if you have heart disease and are on medications for it. Additionally, those with kidney disease or lupus should not be taking vitamin D supplements without their doctor's direction.
The recommended daily value will be different for everyone. It will be affected by your health, environment, diet, even the pigment of your skin. However, one thing that is difficult to ignore is that while our lifestyles have changed dramatically over the last few decades, taking us of the sun into cubicles and cars, the recommended daily values for vitamins and minerals hasn't kept pace. Something to think about tomorrow morning, as you stand at the bus stop, in the dark.
Be healthy,
Dr. Ohlhauser
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