If people on St. John's wort were depressed before, imagine how they'll feel when they realize the supplement is interfering with their contraceptive pills. Recently, two Swedish women and at least seven British women have gotten a little more than they expected when the St. John's wort they were taking for depression interacted with their oral contraceptives, resulting in unwanted pregnancies. Sweden has now made it mandatory that all St. John's wort products carry warning labels, alerting the public to such unfortunate drug-supplement interactions. St. John's wort is not the only supplement that women should be wary of when taking oral contraceptives chasteberry, red clover, and echinacea can also reduce the efficacy and increase the side effects of the pill. People should be aware that the dietary and herbal supplements they are taking to improve their health could have potentially life-changing consequences.
In the American Council on Science and Health's What's the Story: Scientific Facts about Drug-Supplement Interactions a variety of supplement-drug interactions are described.
First, when the drug and supplement have similar actions in the body, they may produce an excessively strong effect. For example, the mixture of the anti-anxiety medication, alprazolam (Xanax), and the supplement kava kava could lead to disorientation. Or mixing a blood thinner such as Coumadin with feverfew, garlic, gingko biloba, ginger, or vitamin E can increase the risk of bleeding.
Second, the supplement may counteract the effect of a drug. For example, supplements such as vitamin E, zinc, or echinacea, can interfere with drugs taken to suppress the immune system, such as corticosteroids and cyclosporine. These same antioxidant supplements can negate the benefits of cholesterol-lowering drugs, such as niacin and "statin" drugs. And, in a recent study from the National Institutes of Health, it was found that garlic supplements, which are used to boost immunity, could sharply reduce the blood levels of the anti-HIV drug saquinavir in AIDS patients.
Supplements may also affect the absorption of drugs from the digestive tract into the bloodstream. For example, if a supplement, such as calcium, is taken at the same time as the thyroid drug levothyroxine or the antibiotic tetracycline, then less of the drug is absorbed into the bloodstream and it won't be as effective.
Finally, supplements may affect the way the body breaks down a drug. For example, St. John's wort can effect the breakdown of drugs used to treat heart disease, cancer, AIDS, drugs for the prevention of organ transplant rejections, and, as most recently reported, oral contraceptives.
There are also certain supplements, vitamins, and minerals that are dangerous when taken alone or when accompanied by a health condition. Ephedra, also known as ma huang, has been linked to nearly seventeen deaths and can cause damage to the heart and nervous system. Chaparral, comfrey, germander, and high does of vitamin A can cause potentially fatal liver disease. Garlic and ginger are dangerous for diabetics, while magnesium is harmful to individuals with liver disease. Large doses of vitamin D can damage the kidneys, large doses of vitamin B6 can cause neurological damage, and too much selenium can cause gastrointestinal and neurological problems.
Also, consumers should be aware that supplements may not contain as of the active ingredient as they claim to; on the other hand, they could include ingredients not listed on the label at all. This has been a concern lately in the sports world. Last year, the International Olympic Committee reported that nearly 25% of the 600 analyzed over-the-counter nutritional supplements contained banned substances that were not listed on the label and could lead to a positive drug test. The Committee subsequently cautioned athletes to avoid all supplements, but these same athletes feel pressure to use supplements to "maximize" their bodies' potential. In December, Pavle Jovanovic, a member of the U.S. Olympic bobsled team, tested positive at the Olympic trials and was disqualified. Jovanovic ingested norandrostendedione unknowingly, either through a supplement, nutrition bar, or protein powder. The American Bobsled Federation said that it "does not believe that the athletes should bear the burden of an unregulated supplement industry that cannot guarantee all ingredients are identified on its labels." We can only hope that with increased publicity, especially surrounding the recent Olympic winter games, the supplement industry will begin to be held accountable for the mislabeling and adverse effects of their "natural" remedies.
How can consumers protect themselves? The American Council on Science and Health advises you not to ingest more than the recommended daily intake of any supplement, vitamin, or mineral, unless advised by your physician. One-third of individuals admit to exceeding the recommended dose of over-the-counter medications and herbal supplements, which only increases the risk of adverse effects. Also, you shouldn't use supplements as a substitute for medical treatment. If you have a persistent health condition, then you should consult your doctor and not try to self-treat it. And, finally, you shouldn't take any supplement that may contain risky ingredients, such as ephedra, yohimbe, comfrey, chaparral, germander, lobelia, wormwood, and gamma-butyrolactone (GBL). Before taking any supplement, it is always wise to discuss it with your doctor, especially if you are pregnant, chronically ill, elderly, under the age of eighteen, or taking other medications.