Dietary supplements are a common find in Canadian medicine cabinets. Whether it be in the form of multivitamins or Garlic capsules, the national health product trend is not going away. A survey published by the Canadian Health Network in 2000 found that two out of three Canadians had used a natural health product (NHP) in the past month— and in that same year spent $1.8 billion on these products. There are a number of reasons why Canadians are turning to NHPs. A growing suspicion of synthetic drugs, and a general reverence for anything natural are some reasons behind this change in consumer attitudes. Marketing also has played a role, with flashy advertising flaunting the natural properties of these products. Canadians are seizing this opportunity to self-medicate, sometimes without knowing what the consequences to their health could be. So with the belief that they can't hurt themselves, they are putting a lot of stock and pouring a lot of money into these products. While most people understand that mixing different types of drugs can be hazardous, some people don’t realize that NHPs and drugs can interact as well. And just like drug-drug and drug-food interactions, the end results can sometimes be harmful or even fatal. Understanding interactions Meet Dr. Brian Foster. He’s a research scientist with Health Canada and heads a team tasked with studying these type of interactions. Since 1991, his team at the University of Ottawa's faculty of medicine along with three other universities, have been looking at the issue of how substances like herbs affect humans. When he first started in this area of research Dr. Foster says he never would have thought he would have uncovered the data that he did, because at first his study wasn’t about dissecting NHP-drug interactions. “Initially, it was setup to look at various nutricuticals which are functioning foods,” he says, meaning the study was originally designed to look at what substances in foods like carrots could do to the human body. But as they delved deeper into the subject, they soon expanded into natural products like herbs because“we found that we were among the first to come up with solid scientific evidence that these products have the capacity to interfere with major drug metabolizing enzymes in the human body,” he says. Just add science Dr. Foster says once they stumbled across this finding, it was only a matter of coming up with the hard science to prove it. His team began a series of more focused studies, the first of which included a study on whether garlic supplements could interfere with some types of drugs AIDS patients were taking. The results surprised them. “We ended up finding a couple of adverse events in the AIDS community,” he says. What exactly those “adverse events” were included a possibly toxic interaction between garlic supplements and certain HIV-impeding drugs. Dr. Foster’s results did not show conclusively why these reactions occurred. However, a lab in the U.S. came up with similar results; they found garlic could reduce the amount of HIV-impeding drug in patient bloodstreams. This was enough for researchers to warn AIDS patients not to take garlic-supplements while on these drugs. Soon after, Dr. Foster decided to increase the scope of the research. To date, they’ve been able to evaluate over 175 different NHPs, including 30 types of garlic, 15 types of echinacea, and about a dozen types of St. John’s wort. “[Some] products we looked at with great detail,” he says. “Sometimes it was just a single product we had looked at.” Problematic Products What Dr. Foster soon found with this research was, with the possible of exception of Ginseng, all NHPs had the potential to interfere with the safety and efficacy of drugs in humans. But what they came across next was most surprising. While studying the effects of St. John’s wort and garlic on antibiotic medication, they discovered that these NHPs could actually make antibiotics more effective in the short term. However, in other studies, an opposite effect was shown. Some types of antibiotics were made less effective when used in conjunction with garlic and St. John’s wort. This “two-pronged” interaction of the NHPs and antibiotics still defies explanation. “We’re just doing the second part of the study now,” he says. “But it was enough to warn us that it could seriously alter the safety of antibiotics as well.” Similar findings have been found in lab studies in the United States as well, he says. While it may appear that most of Dr. Foster’s research has been about establishing what kinds of NHPs interact with medication, he has also been trying to answer the question as to why these interactions are occurring in the first place. Risks and benefits Common sense says that anything you put into your body will have some sort of effect on you. The effect may be small or large—it all depends on the substance and the dose. All substances also carry a certain “risk-to-benefit profile,” Dr. Foster says. What this means is while herbal supplements like St. John’s wort may help battle the winter blues, there’s also a certain amount of risk involved (i.e. the person may be mildly allergic to the herb). Medications like antibiotics also follow the same rules. Problems occur when the risk-to-benefit factors of both substances are mixed together. So when a patient is prescribed antibiotics for a mild infection, and the patient decides to take St. John’s wort on the side, an interaction occurs. This interaction may take any type of form, depending on the person. “So in this case, it’s a nasty infection... your infection may flare up after a couple of weeks and you’ll have to go back and get more drugs,” says Dr. Foster. Serious business While this may not be a big deal to the person with the mild infection, it may be more serious for people who are severely ill. People on heart medication, or those afflicted with AIDS or cancer might get very serious reactions as a result of the two substances interacting. In the heart-patient’s case, the blood-pressure medication he may be taking is reduced in the blood stream because the garlic supplement he is taking on the side is effecting the rate the medication is released into the body. This might lead to the patient having higher blood pressure, which may in turn lead to more heart trouble down the road. “So if you change the risk-to-benefit (profile), it could be very innocuous or very serious,” Dr. Foster says. But Dr. Foster’s research has also shown that the interaction of the two risk-to-benefit profiles doesn’t always end in a serious situation for the patient. Why this happens remains the focus of study for Dr. Foster’s team. “This is where we have been going with some of the work,” says Dr. Foster. “We want to propose more clinical trials with AIDS and cancer patients.” Risks vs. results Should Canadians be concerned when taking NHPs with medication? Dr. Foster says yes, but don’t throw out all your herbal supplements yet. “All NHPs have inherent risks,” he says. “In most cases, these risks are low.” Dr. Foster cautions that people should only use these products in moderation and under the supervision of a physician. “Patients taking medications should consult with their health care
professionals and inform them of all NHPs that they are taking,” he
says. “Then they should listen carefully to the advice provided.” |
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