NEW YORK -- One in three adults in the U.S. is taking both prescription medications and dietary supplements, creating a risk for dangerous interactions, according to a new study.
Multivitamins with added ingredients like herbs or 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 in an email.
Lieberman, the study's senior author, is a researcher with the Military Nutrition Division of the U.S. Army Research Institute of Environmental Medicine in Natick, Massachusetts.
Lieberman said the team did this study to determine how many people in the U.S. are using dietary supplements and prescription medications together, and whether patterns of dietary supplement use are different among people with various kinds of medical conditions.
"This information can help health care professionals to identify who may be at risk of having an adverse interaction between a supplement and prescription medication," he said.
%VIRTUAL-article-sponsoredlinks%For their study, Lieberman, along with lead author Emily Farina and their colleagues, used information taken from the 2005-2008 National Health and Nutrition Examination Survey, which represents the entire national population.
The researchers focused on 10,480 adults (4,934 women who weren't 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 medical conditions: asthma, arthritis, congestive heart failure, coronary heart disease, angina, heart attack, stroke, high blood pressure, high cholesterol emphysema, chronic bronchitis, cancer, weak bones or problems with the liver, thyroid or kidneys.
The researchers found that 47 percent of participants diagnosed with any of those medical conditions used both supplements and prescription medications. That compared to about 17 percent of adults who didn't have those conditions, but were taking prescription medications for other reasons, such as birth control pills or antidepressants.
Overall, 34 percent of the participants -- representing some 72 million people in the U.S. -- were taking some kind of dietary supplement along with a prescription medication, according to the results published in the Journal of the Academy of Nutrition and Dietetics.
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 than standard multivitamins. The ingredients most often added to the enhanced multivitamins included fish oil, botanicals, herbs, probiotics, fiber, enzymes, antacids and glucosamine and chondroitin.
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 findings "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.
Annette Dickinson told Reuters Health that the large number of people who used both supplements and prescription medications in the study didn't surprise her.
Dickinson is a consultant for the Council for Responsible Nutrition, a supplement industry trade group, and an adjunct professor in food science and nutrition at the University of Minnesota.
She wasn't involved in the new study, but has researched some of the reasons why consumers take dietary supplements.
"Obviously anybody who is taking prescription medication should be telling their doctor everything they're taking so that a judgment can be made whether there is, or might be, an issue," she said.
Dickinson added that pharmacists may also be a good source of information on medications and dietary supplements, but she doesn't think that should be a substitute for speaking with a doctor.
"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.
Lieberman added that if a patient is concerned, then bringing the supplement's original container will help doctors and other healthcare providers identify ingredients in supplements that have a potential to interact with medications.
"Patients can also use reputable sources to check if there have been reports about interactions of dietary supplements they are considering taking and their medications."
The National Institutes of Health MedlinePlus website, for example, has information on interactions between drugs, supplements and herbal ingredients.
12 Ways to Save Money by Going Green
Study: 1-in-3 Americans Mix Supplements with Meds
Strategic planting of trees can reduce an unshaded home's air conditioning costs 15 percent to 50 percent, according to the U.S. Department of Energy, which has tips on landscaping for shade. Some tility companies offer customers free trees throughout the year, and some local governments give away trees as part of Arbor Day celebrations. For $10, you can join the Arbor Day Foundation and get ten free trees. Plus, your membership entitles you to a 33% discount on trees when you buy online from the foundation.
By leaving your car at home two days a week, you can reduce your greenhouse gas emissions by more than 3,000 pounds a year, according to the U.S. Environmental Protection Agency. Plus, you'll save money on gas and parking if you bike rather than drive to work. For example, you'll save about $7 a day by biking rather than driving if you have a 15-mile round-trip commute. The How Much Can I Save Biking to Work? Tool analyzes your financial benefits. If biking isn't an option, you still can drive less by organizing a carpool, using public transportation or walking.
You can save an estimated 10 percent a year on heating and cooling costs by installing a programmable thermostat, according to the Energy Department. Save energy in the winter by setting the thermostat (which costs as little as $20) to 68 degrees while you're awake and programming it for a lower temperature while you're asleep or away from home. Set it for 78 degrees in the summer and increase the temperature when you're not home. You can shave 1 percent off your bill for each degree you decrease the temperature in the winter or increase it in the summer. And, no, you won't have to use more energy to warm or cool your house off when you get home. That's a common misconception, according to the Energy Department.
The meat industry generates about one-fifth of the world's man-made greenhouse gas emissions, according to estimates from the United Nations' Food and Agriculture Organization. So if your family skipped eating steak once a week, it would be the equivalent of taking your car off the road for nearly three months, according to the Earth Day Network. And you'd save money. For example, a sirloin steak costs twice as much per pound as chicken breasts and nearly five times as much as beans, according to the U.S. Bureau of Labor Statistics.
You can save $70 a year on your energy bill by replacing the light bulbs in five of your most frequently used fixtures with Energy Star qualified LED or CFL bulbs, according to the EPA. These bulbs use 75 percnet less energy than traditional incandescent bulbs and last ten to 25 times longer.
You can save money on your water bill by installing water-efficient faucets, showerheads and toilets. Look for products with the WaterSense label, which means they are certified to be at least 20 percent more efficient without sacrificing performance. For example, WaterSense-labeled toilets can save a family of four more than $90 annually on their water bill and $2,000 over the toilet's lifetime, according to the EPA. Considering you can get a toilet with the WaterSense label for as little as $98, it will pay for itself in about a year. Estimate your savings with this simple calculator.
Americans discard more than 2 million tons of obsolete electronic products annually, according to the EPA. Rather than fill the dump with your unwanted gadgets, fill your wallet by selling them. Sites such as BuyMyTronics.com, Gazelle, NextWorth and uSell pay cash -- and cover the cost of shipping -- for electronics such as smartphones, tablets, computers and more. The type of electronics you can sell varies by site, as does the amount you can receive. If none of the sites will accept your unwanted electronics, see the EPA's eCycling list for responsible electronics recyclers.
Americans spend $5.25 billion on fertilizers for their lawns, according to the EPA. Yet, you can get fertilizer for free by composting leaves, grass clippings, vegetable scraps and other organic waste. Plus, composting can divert as much as 30 percent of household waste from the garbage can, according to Eartheasy's guide to composting.
You may be able to cut your water costs a little by installing rain barrels at downspouts to collect water. You can attach a hose to the barrels to water your lawn and garden. The cost can be free (from some water departments), cheap (a recycled large plastic trash can or metal drum) or expensive (about $100 for a 50-gallon barrel at home and garden centers and online.
You're doing your health a favor by drinking water rather than soda. But if you're buying bottled water, you're not doing your wallet or the environment a favor. According to the International Bottle Water Association, Americans spent $11.8 billion on bottled water in 2012. Considering that the average cost per bottle is $1.45 and the average consumer buys 167 bottles a year, you'll spend more than $240 a year on bottled water at that rate. For the cost of just a few disposable bottles of water you can buy a reusable bottle that you can fill and carry with you wherever you go.
Clothes dryers can be one of the most expensive home appliances to operate, accounting for approximately 6 percent of a home's total electricity usage, according to the California Energy Commission's Consumer Energy Center. Because all dryers use about the same amount of energy, the best way to save money -- and benefit the environment -- is to line-dry your clothes whenever you can.
Energy vampires –- electronics that draw power even when they're not in use –- cost Americans almost $10 billion a year and account for almost 11 percent of all U.S. energy use, according to the EPA. If you want to avoid unplugging all of your electronics when they're not in use, you can buy an inexpensive power strip that several things can be plugged into and turned off with the flip of a switch. The Smart Strip Power Strip ($25 and up) will automatically shut off computer peripherals, such as printers and scanners, when not in use. And the Belkin Conserve Smart AV ($29.99) automatically shuts off components, such as a gaming console, receiver and speakers, when you turn off your TV.