Adverse reactions to vitamins C and D can be avoided. Make sure you understand all of the information before purchasing a natural health product or a drug.
There have been 32 adverse reactions to vitamin C as of May 2008, according to the Canada Vigilance Online Database hosted by Health Canada. But hold on! Before you get nervous and chuck out the bottle that you just bought, let’s dig deeper.
Between 1965 and 2008–a span of more than 30 years–32 suspected adverse reactions have been reported that are associated with the hundreds, if not thousands, of different vitamin C products that have been on the market during that time.
These reactions have occurred in all age groups of the more than 71 percent of Canadians (23 million) who currently use natural health products.
These statistics have a few holes. The reporting of adverse reactions is voluntary and under-reporting is common, not only for natural health products but for pharmaceutical drugs as well. A Health Canada employee told alive that although they are working to improve their system using a recently upgraded database, current data still represents only suspected incidents. These are based on the reporter’s impressions and thoughts; they are not confirmed by investigators, and they are not causal links.
Most vitamin C-related reactions occur in people who are combining natural health products or taking natural health products with pharmaceutical medications. This makes investigation much more difficult, since the cause may be any number of things.
Suddenly, vitamin C is starting to sound relatively innocuous, isn’t it?
This breakdown shows how easy misinterpretation is at first glance and–for a consumer–how difficult it can be to get the real story.
Gimme an A for Antioxidants
Should I be taking antioxidants? This is a question that you may have asked yourself after a study in The Journal of the American Medical Association (2007) reported that antioxidants such as vitamins A and E may “significantly increase mortality.”
This meta-analysis, which also questioned vitamin C’s benefit in the reduction of mortality rates, received impressive media coverage.
But Dr. Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University–a leading orthomolecular research centre–called it “a flawed analysis of flawed data” because it focused on a small group of trials. It disregarded the predominantly opposite conclusions of a vast amount of positive data from laboratory, animal, and human observational and experimental studies.
“Instead of causing harm, the totality of the evidence indicates that antioxidants from foods or supplements have many health benefits, including reduced risk for cardiovascular disease, some types of cancer, eye disease, and neurodegenerative disease,” he stated in an Oregon State University press release. “In addition, they are a key to an enhanced immune system and resistance to infection.”
Of the 815 antioxidant trials the researchers considered, only 68 were used in the analysis, noted Frei. Two especially important, but rejected studies, found substantial benefits and reduced mortality from the intake of antioxidant supplements.
Frei said that all the new study really demonstrated was “a bias toward identifying studies or research that shows harm caused by antioxidants, and selective removal of research that shows benefits.”
Gimme a B for Bias
We get messages from the media, our friends, our family members, and our neighbours down the street, each of whom has a bias.
According to a new study, so do medical journals.
In 2007 University of Florida researchers examined the relationship between drug advertising and medical journals’ publication of articles about nutritional supplements. Researchers looked at one year of the issues of 11 major medical journals to analyze pharmaceutical advertising and content about dietary supplements. The results revealed that “Increased pharmaceutical advertising is associated with publishing fewer articles about dietary supplements and publishing more articles with conclusions that dietary supplements are unsafe.”
Will this hypothesis stand the test of time? Maybe, but it won’t be the first study to be called into question.
One of the criticisms directed at the $2.5 billion industry, comprised of about 50,000 natural health products in Canada, is that the science isn’t there to support their claims. While that may sometimes be true, times are changing–fast.
“There’s more research being done now than in the past,” says Dr. Jason Boxtart of the Body Balance Centre for Integrative Medicine in Prince George, BC, and incoming chair of the Canadian Association of Naturopathic Doctors (CAND). “The use of natural health products has grown so much in recent years that now researchers are finding there’s funding, whereas in the past, there wasn’t.”
“In general, there’s a huge void of research that has to be done,” he told alive. “History has told us that natural health products are useful and safe but really, the evidence needs to get to a higher place than it is now.”
Gimme a C for Contradiction
“We believe in the importance of research and support it,” says Penelope Marrett, president and CEO of the Canadian Health Food Association (CHFA).
“Evidence either helps to change our thinking, reaffirm something already proven, or provide a baseline of knowledge. It may even be contradictory, which helps to build a body of evidence and creates discussion,” she told alive.
Discussion was ignited when Johns Hopkins’ researchers published a meta-analysis in January 2005 stating that more than 400 IU a day of vitamin E may increase mortality and should be avoided.
The Alliance for Natural Health, a UK-based nongovernmental organization that focuses on natural health issues, promptly pointed out the study’s limitations. For starters, all trials in the study used only one form of a synthetic vitamin E (alpha-tocopherol), whereas naturally sourced vitamin E has been proven to help prevent heart disease and cancer.
“It’s common to find a contradictory study,” Boxtart agrees. “It depends on the hypothesis, the way the study was done–many things. What we try to do is essentially integrate the latest evidence into practice. What doesn’t happen and what’s not reasonable to do is to keep changing what you do every time the wind changes. You have to look at the preponderance of evidence.”
Calcium, beta carotene, vitamins D and E, and multivitamins are among those supplements that have been called to the mat lately–not only in terms of potential benefits, but also in terms of potential risks.
Vitamin D, for example, helps in the maintenance of teeth and bones and the absorption of calcium and phosphorus; it may also reduce the risk of cancer, osteoporosis, heart disease, high blood pressure, and certain types of cancer. On the “risk” side is hypercalcemia.
Research supporting vitamin D is fairly strong. But if I take 1,000 IUs of vitamin D during the fall and winter as recommended by the Canadian Cancer Society, will I get hypercalcemia, a higher-than-normal calcium level in the blood? Just how much of a risk are we talking about?
Vitamin C is essential for a host of bodily functions, including wound healing, tissue formation, iron absorption, collagen production, teeth and bone maintenance, and protein and fat metabolism. But if I take my typical 500 mg a day, am I going to get diarrhea, interfere with my iron metabolism, and develop kidney stones?
And what about my daily multivitamin, a habit encouraged by the Journal of the American Medical Association?
“If you took a natural health product as directed, by and large, you wouldn’t get a toxic effect,” says Boxtart. “What people are talking about with toxicity is taking large doses for a long time, and even then, only a few people will experience side effects.
“Natural health products can have risks–that’s true. But the risk is pretty small. We know this. We would be hearing a lot more about negative side effects if they were happening on a huge scale,” he says.
Boxtart says it’s largely unfair to compare the safety of natural health products to pharmaceutical drugs because it’s such a broad context. But let’s try, just so no one accuses alive of being biased.
Varenicline tartrate is an antismoking drug that was approved in Canada in April 2007. By November 2007 Health Canada had received 107 adverse reaction reports including 14 cases of aggression, depression, and suicidal ideation. In the United States 34 suicides have been linked to varenicline tartrate.
Let’s compare: 32 adverse reactions linked with vitamin C over 33 years in millions of users versus 107 adverse reactions over seven months in the 220,000 Canadians prescribed this single drug.
Although an article on varenicline tartrate was published in the May 2008 National Reviewof Medicine for physicians, media coverage has been minimal.
Gimme a D for Vitamin D
“Natural health products are low risk in nature,” agrees Marrett of the CHFA. “Health Canada wouldn’t be promoting multivitamins or folic acid without demonstrable benefits. The Canadian Cancer Society has increased their vitamin D recommendation. The Canadian Paediatric Society has also said that Canadians need more vitamin D. They would only do that if the research is compelling.”
It’s also compelling to Dr. Lesley Horton, who practises integrative medicine for mind-body-spirit in Vancouver, BC. “The short answer is, yes I do recommend supplements and I didn’t used to,” she told alive. “Theoretically, we should get all of our nutrients from a well-balanced diet following Health Canada’s Food Guide. In reality, food has 40 to 50 percent fewer nutrients than it did 50 years ago.”
Horton also points out that recommended dietary allowances (RDAs) represent a nutritional minimum to prevent disease. “They’re not about optimization,” she says, adding that researchers are still learning a lot about adequate nutrient levels and are constantly bumping up their recommendations for vitamins such as C and D.
A larger concern than interactions caused by combining natural health products is the possibility of interactions between drugs and natural health products.
Gimme an E for Education
Currently in Canada there are about 22,000 prescription medications on the market. One-third of Canadians use botanicals (plants and plant substances such as herbs) daily. One-third of Canadians use botanicals with prescription medications and over-the-counter drugs, according to surveys compiled by CAND between 2000 and 2006.
“There is minimal research or case reports that indicate drug-botanical interactions. There are also a number of drug-botanical interactions that have been reported or theorized that have turned out to be inaccurate in practice,” states a CAND position paper.
As time goes on, grey areas of knowledge will hopefully be filled in. In the meantime, “if you’re taking both natural health products and pharmaceuticals, definitely talk to your medical doctor, your naturopathic doctor, or your pharmacist,” advises Boxtart. “If you’re taking a natural health product to actually treat a medical problem, at a minimum, it should have been diagnosed by a physician. Get some advice from someone who knows about natural health products.”
Without a doubt, the media plays a valuable role in informing the public and in contributing to the progression of knowledge, but often with some degree of bias, so when conducting personal research, develop a critical eye. If you come across a headline such as “Can a vitamin kill you?” the article might be worth a read, and an Internet check for industry rebuttal, and depending on what you find, a letter to the editor.
“There is no doubt that better communication and education needs to happen, not only between consumers and their health care practitioners, but also between the media and the consumer,” Marrett of the CHFA wrote in response to a recent article about hazardous vitamins. “The media has the responsibility to ensure balanced reporting, including the use of fair and accurate headlines.”
To consumers, Marrett reiterates the importance of becoming informed. She says, “Make sure that you understand all of the information before purchasing a natural health product or a drug.”
