One in three adults in the US are taking both prescription medications and dietary supplements, creating a risk for dangerous interactions, according to a new study.
April 30, 2014 (Reuters)
Multivitamins with added ingredients like herbs and fish oil were the most common form of supplement mixed with medications, researchers found. “Multivitamins are commonly assumed to be safe, but our analysis suggests multivitamins, which may include multivitamin ‘plus’ combination products, can also contain botanical and herbal ingredients that have the potential to interact with prescription medications.” Harris Lieberman told Reuters Health. Lieberman, the study’s senior author, a researcher with the Military Nutrition Division of the US Army Research Institute of Environmental Medicine (USARIEM) in Natick, Massachusetts.
For their study, Lieberman and his colleagues, used information taken from the 2005-2008 National Health and Nutrition Examination Survey (NHANES), which represents the entire national population. The researchers focused on 10,480 adults (4,934 women who were not pregnant and 5,016 men) who answered survey questions about their dietary supplement and prescription medication use, as well as whether they had any of the following conditions: asthma, arthritis, congestive heart failure, coronary heart disease, angina, heart attack, stoke, high blood pressure, high cholesterol, emphysema, chronic bronchitis, cancer, weak bones or problems with the liver, thyroid or kidneys.
The researchers found that 47% of participants diagnosed with any of those medical conditions used both supplements and prescription medications. That compared to about 17% of adults who didn’t have those conditions, but were taking prescription medications for other reason, such as birth control pills or antidepressants. Overall, 34% of the participants – representing some 72 million people in the US – were taking some kind of dietary supplement along with a prescription medication. Cardiovascular medications were most likely to be used along with dietary supplements, followed by central nervous system agents, hormones, metabolism-related drugs, psychotherapeutic agents and antibiotics or antivirals.
Multivitamins containing other ingredients were more common that standard multivitamins. The ingredients most often added to the enhanced multivitamins included fish oil, botanicals, herbs, probiotics, fiber, enzymes, antacids and glucosamine and chondrotin.
Supplement use was most common among people with diagnosed osteoporosis, followed by those with thyroid, cancer, arthritis, cardiovascular, kidney, diabetes, respiratory and liver conditions.
The authors call the finding “concerning” because some herbal supplements are known to alter the way the liver metabolizes drugs, and can increase or weaken the potency of a medication. “Patients, especially those taking medications or given new prescriptions, should always inform their doctors about what dietary supplements they are taking, and doctors can help patients by asking about their supplements,” Lieberman said.
Drug – herb interactions are common, so common that I have a 700 page textbook on herbal safety. I am constantly looking for potential interactions in my patient population. The herbs are really quite safe, when taken properly; it’s the way in which they react to many drugs that is at issue.
Honestly, drug – drug interaction is a much bigger issue. For example, lovastatin, commonly prescribed to lower cholesterol (currently taken by 49% of the population over the age of 60) has 214 known drug interactions, representing 632 band and generic drugs on the market.
The average American takes four prescription medications with little or no knowledge about how these drugs interact. It is estimated that a third of all cases of senile dementia in our country are from overprescribed medications.
The multivitamin is not really an issue. Recent studies have found they have little if any value in human health. The “plus” combinations in many multiple supplements contain so little content that they are neither helpful nor harmful. As noted in an earlier blog, herbal quality in the US in non-existent. Contamination is a bigger issue in the “proprietary blend” of herbs noted on the label.
Silymarin (milk thistle), St. John’s Wort and Black Cohosh will either increase or decrease drug clearing time through the cytochrome P450 liver pathway. This is a common metabolic pathway for many prescription drugs. However there are alternatives when medications prevent safe use of these herbs.
Ginkgo is a potent blood thinner and should not be used with other blood thinners, like Coumadin. The blood thinning effects of fish oil are generally overstated.
THE BOTTOM LINE:
You should review all the "drug to drug" and "drug to herb" interactions of any prescription medications you take. Throw that multiple vitamin away, it’s worthless anyway. Please do not take herbs without consulting a qualified nutritionist. They are potent and can be harmful it not taken properly.
I believe people who take supplements with medications are just looking for help. The drugs don’t restore their quality of life and they just hope that supplements will be of some benefit.