In 2014, the Council for Responsible Nutrition (CRN) reported that 68 percent of adults in the U.S. were taking dietary supplements, including multivitamins, fish oil, calcium and vitamins C and D.
Another survey indicated that 83 percent of regular users felt confident in the “safety, quality and effectiveness of dietary supplements.” While supplements can offer many benefits, the potential for negative interactions should also be considered and noted so that you can properly advise your patients.
A 2012 literature review identified specific herbs and supplements as problematic. The authors found that products containing St. John’s Wort, magnesium, calcium, iron, and gingko biloba demonstrated the highest number of adverse effects when taken with medications. Additionally, the review cited flaxseed, Echinacea and yohimbe as having a significant amount of “documented contraindications.”
These findings prompted the authors to recommend better communication between health care professionals and their patients to explain these interactions and help guide their usage.
Scott Michael Schreiber, DC, CNS, and a chiropractic physician in Newark, Delaware, takes this advice to heart, but also believes that patients should take a proactive approach to their health – with a caveat. “[Patients’] self-treatment has the potential to interact with prescription and over-the-counter medications, causing potentially disastrous consequences,” he says.
Some common drug-supplement interactions can increase or delay absorption by metabolizing the drugs, Schreiber notes. He warns that any supplement or herb has the potential to cause an adverse effect and emphasizes that chiropractors have a responsibility to ask patients about their use of these products.
A few to watch
Schreiber cites negative side effects from taking vitamin E, which might interfere with antidepressants, aspirin, warfarin (Coumadin) and cancer treatment drugs. “Asian ginseng may alter the effects of blood pressure medication, specifically calcium channel blockers and may decrease the effectiveness of blood thinning medications, including aspirin,” he says.
When taken with caffeine, asian ginseng could “hyperstimulate the central nervous system and may exaggerate the effects of anti-psychotic medication.”
White willow bark has anti-inflammatory properties , but may also reduce the effects of beta-blockers and diuretics, while increasing risk of gastrointestinal symptoms and enhancing the effects of drugs intended to thin the blood, according to Schreiber.
He also urges care when taking coenzyme Q10, which could lower blood pressure, and evening primrose oil, which increases the risk of seizures when taken in combination with drugs for schizophrenia and other psychotic disorders.
Schreiber also cautions that valerian, long used for insomnia, anxiety and nervousness could increase the effect of sedatives and anesthesia. He nixes the use of kava kava while drinking alcohol, since “the risks of impairment and liver damage are increased.” This supplement could also negatively impact anti-anxiety and antipsychotic medication effects, he adds.
Goldenseal may address certain allergy or infection-related inflammatory conditions , but Schreiber indicates that it may also decrease the effectiveness of antibiotics and the way the liver metabolizes medications.
Schreiber recommends a variety of supplements to his patients, but exercises caution regarding the interactions with prescription medications. “I also encourage the patient to let the treating physician know that they are taking supplements,” he says. “When the patient begins a nutritional program with me, I also send the primary care physician a letter so that we are all on the same page.”
Admittedly, it is impossible to memorize all the potential interactions, Schreiber says. “But it’s imperative that you check to make sure the supplement you are recommending or that the patient is taking is helpful.”