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Winnipeg Free Press - PRINT EDITION

Bug repellent

Virus-catching season is officially open; can you protect yourself with vitamins C & D and COLD-fx?

By: Shamona Harnett

9/11/2009 1:00 AM | Comments: 0

While cramped like a sardine in a tin on a flight from Denver to Santa Ana recently, I understood just how vulnerable we are to catching nasty viruses.With the aircraft packed to capacity, I covered my face with my arm whenever I heard a cough or a sneeze -- and that was often. My husband and I both laughed each time I did this. We knew that it was a bit silly since flu-infected droplets could very well travel to our nose, mouths and eyes regardless of how we covered our faces.

During the flight, I often checked the three bottles I had in my purse. They were vitamin C, COLD-fx and vitamin D. Having them in my immediate possession (illogically) made me feel better. I was happy to have been taking daily doses of these items. Perhaps they could help me fight off whatever bug someone could sneeze or cough my way.

But do they really work?

The verdict is still out, but here's what scientists know:

Vitamin C

What it is: Also known as ascorbic acid, vitamin C is a water-soluble vitamin scientists say prevents cell oxidation while boosting tissue repair, wound healing and gum health. Fruits and vegetables -- particularly lemons, limes and oranges -- are good sources of vitamin C. Because the human body cannot make or store this compound, people need a continuous supply of it.

Cold and flu connection: Late American chemist and Nobel Prize winner Linus Pauling was the world's biggest vitamin C proponent whose work generated public interest in taking mega doses of vitamin C. His 1970 book, Vitamin C and the Common Cold suggested that taking doses of 1,000 mg of vitamin C daily could boost the immune system and reduce incidences of the cold by 45 per cent. He later revised that book saying that even higher doses of vitamin C could prevent the flu. Pauling and his wife took extremely large doses of vitamin C saying that doing so reduced their cold and flu incidences. Most of the scientific world says that there is no hard science -- in the form of multiple large, randomized, double-blind, placebo-controlled trials -- supporting this theory. Nevertheless, thousands of people around the world swear that their daily dose of vitamin C has lessened and even prevented their instances of cold and flu.

Safety: Health Canada says vitamin C deficiency in North America is rare. The federal agency recommends a maximum dose for adults of 2,000 mg. (That includes vitamin C from foods and supplements). Side-effects of taking too much vitamin C include nausea, gastric symptoms and kidney stones. People with impaired kidney function should watch their vitamin C intake. Experts say that dividing your supplemental dose of vitamin C may allow your body to use it more efficiently. Chewing on vitamin C tablets -- they are very acidic -- can erode teeth and cause mouth irritation.

COLD-fx

What it is: Invented by Edmonton-based Afexa Life Sciences Inc., this capsule is made of purified North American ginseng extract. Its makers say this form of ginseng has a different chemical profile than Asian ginseng, which is associated with increased mental alertness and mood improvements. Rather, the type of ginseng extract found in COLD-fx is supposed to stimulate the body's natural killer cells and antibody-producing cells. Several high-profile professional athletes in Canada have said they take COLD-fx.

Cold and flu connection: COLD-fx packages contain the Health Canada-approved claims that the product "Helps reduce the frequency, severity and duration of cold and flu symptoms by boosting the immune system." The company has several studies to back up its promises, including one published in a 2005 issue of the Canadian Medical Association Journal. This randomized, controlled trial studied 323 people who had suffered at least two upper respiratory infections in the previous year. It found that those taking two 200 mg capsules of COLD-fx daily for four months reduced their average number of respiratory infections by 25 per cent and reduced number of recurrent respiratory infections by 56 per cent. According to the company website, 679 people have participated in COLD-fx clinical trials so far.

Safety: The manufacturers of COLD-fx warn that pregnant women, children under age 12 and those taking blood thinners should not take COLD-fx. Those with serious medical conditions should consult their doctors before taking. On previous packages of COLD-fx, the company recommended large doses of the product for three days for "immediate relief" of colds and flu. Health Canada has since forced COLD-fx to remove these claims and dosing instructions from packages. Now, packages instruct consumers to take one 200 mg capsule twice daily.

Vitamin D

What it is: Known as the sunshine vitamin, vitamin D is a fat-soluble compound that we get mostly from sun exposure. It's also found in salmon, eggs and fortified milk. Scientists agree that vitamin D helps the body absorb calcium and phosphorous and therefore prevents diseases such as rickets. More recent studies show that vitamin D may play a role in protecting against cancer and autoimmune diseases such as Type 1 diabetes and multiple sclerosis. Experts say as little as 10 minutes of sun exposure to bare skin daily can prevent vitamin D deficiency. Those who live in northern climates (such as Winnipeggers) as well as those with darker skin -- they don't absorb the sun as well as the fair-skinned -- should make sure they get adequate amounts of vitamin D, say experts.

Cold and flu connection: A study published in a February 2009 issue of Archives of Internal Medicine found that people with the most severe vitamin D deficiency were 36 per cent more likely to suffer respiratory infections than those with adequate levels. Other studies suggest the same type of phenomenon.

The reason? Scientists say that vitamin D increases the production of an antimicrobial peptide called hCAP-18, a protein that helps the immune system kill viruses.

Safety: Health Canada says that the tolerable upper intake level of Vitamin D for adults is 2,000 IU. Vitamin D proponents suggest taking a daily supplement of at least 800 IU. Vitamin D is fat-soluble and therefore toxic at high doses. Too much vitamin D is linked to increased risk for premature heart attack, atherosclerosis and possibly kidney stones in people who are predisposed to kidney problems. Some vitamin D researchers challenge government health agencies about what constitutes too much vitamin D.

Have an interesting story you'd like Shamona to write about? Contact her at shamona.harnett@freepress.mb.ca

Republished from the Winnipeg Free Press print edition November 9, 2009 D1

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