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If you’ve added one or more dietary supplements to the medicine cabinet, you’re not alone. A recent study reports that 80% of Americans use dietary supplements—a 7% increase from 2020. Multivitamins were the most popular, with 75% of supplement users taking them. Others that showed significant increases over the last year were vitamin D (52% versus 42%), vitamin C (40% versus 35%) and zinc (22% versus 15%). 

From pills, capsules and tablets to powders, extracts and liquids, supplements are designed to make up for shortfalls in vitamins and minerals, to achieve wellness goals (like reducing blood pressure), to manage weight or to achieve sports goals.

The constant deluge of advertisements and product marketing would have you think a particular dietary supplement is good for everyone. In truth, however, medical needs and histories differ so widely it can be difficult to determine which supplements, if any, to take. 

While the U.S. Food and Drug Administration regulates prescription drugs and over-the-counter medicines, it takes a different approach with dietary supplements—using a different set of regulations than what’s required of “conventional” drugs. The FDA instead puts much of the responsibility back on the supplement companies:

“Manufacturers and distributors of dietary supplements … are responsible for evaluating the safety and labeling of their products before marketing to ensure that they meet all the requirements.”

The FDA does issue warnings about possible problems with supplements and may take unsafe products off the market, but just because a dietary supplement is sold in the United States, it doesn’t mean it’s safe—or even that it contains what it says it does. In fact, the FDA calls this out on its website for consumers:

“The FDA does NOT have the authority to approve dietary supplements for safety and effectiveness, or to approve their labeling, before the supplements are sold to the public.”

There are some third-party organizations, however, that test supplements for good manufacturing practices, supplement content and levels of harmful substances. These include NSF International, U.S. Pharmacopeia and the Natural Products Association.

Advice for taking dietary supplements

These 10 common vitamins, minerals and herbal supplements are often recommended for older adults, but be aware of the risks of each:

Commonly used for those who may not spend much time in the sun, this vitamin is essential for calcium absorption and works with calcium to build strong bones and prevent osteoporosis. 

Overdoses of vitamin D can cause nausea, vomiting, muscle weakness, kidney failure and even death. Taking vitamin D with certain cholesterol-lowering statin medications can cause the statins to be less effective, and taking it with thiazide diuretics could raise calcium levels too high.

This vitamin helps keep blood healthy and actually helps create DNA. It also helps prevent the blood condition megaloblastic anemia. Some supplements may contain doses higher than the recommended 2.4 micrograms daily (up to 1,000 micrograms) but this is typically safe because our bodies absorb only a small percentage of the supplement. Also, because many older adults don’t have enough hydrochloric acid in their stomachs to absorb vitamin B12 from food, they can better absorb it from supplements. 

Necessary for healthy bones and teeth, this mineral also helps muscles move and nerves carry messages. Overdoses of calcium are rare, but too much calcium can interfere with kidney function, or cause nausea and abnormal heart rhythms. Certain antibiotics and medications for HIV and thyroid problems are not absorbed well when taken within several hours of calcium supplements. And lithium, used to treat bipolar disorder, can lead to abnormally high levels of calcium when taken with the supplement.   

Necessary to protect nerves and form red blood cells, this vitamin is common for seniors. Taking high levels of B6 for a year or longer, however, can cause nerve damage and symptoms like skin patches, sunlight sensitivity, nausea and heartburn. The supplement can also interact with an antibiotic used to treat tuberculosis. 

Also called fish oil, omega-3 is an essential fatty acid the body cannot make itself. But it’s necessary for eye health, heart function and a healthy immune system. One potential danger is that omega-3 may interact with hypertension medications and anticoagulants like Coumadin (warfarin). 

Also known as ALCAR, this amino acid helps cells’ power plants, or mitochondria, function. It may also be helpful in improving cognitive function of people with memory-related diseases like Alzheimer’s. Possible side effects include upset stomach, nausea, vomiting, dry mouth, headaches and restlessness. This supplement may worsen bipolar disorder or make seizures more likely in people who have had them before. It also might interfere with thyroid hormones, so your older adult should not take ALCAR if they have an under-active thyroid.

Used to strengthen the immune system, this flower extract is often taken to ward off colds. Generally safe to take, it’s not recommended for people with auto-immune disorders, as it could make these conditions worse. 

Research suggests this extract may benefit those with anxiety, glaucoma, peripheral artery disease, diabetic retinopathy, premenstrual syndrome, schizophrenia and vertigo. There’s also mixed research that indicates it may help with memory problems related to dementia. However, ginkgo biloba may increase the risk of bleeding and may interfere with anticoagulant and diabetes medications. And eating uncooked gingko seeds and untreated parts of the plant can be toxic to the body.

Asian ginseng is promoted for general health, physical stamina, concentration, memory, immune function, slowing the aging process and more. More studies are needed, but Asian ginseng could interact with calcium channel blockers, blood pressure medications, anticoagulants, statin medications and antidepressants. American ginseng is a different plant, so don’t confuse the two herbs.

This edible bulb is promoted for improving heart health and reducing cholesterol and blood pressure. However, garlic supplements may increase the risk for bleeding, so if you take blood thinners like warfarin or are preparing for surgery, consult your doctor before taking garlic supplements. Garlic may also interfere with a drug used to treat HIV infection, along with some dietary herbs and supplements. 

Find more information about specific supplements in National Institutes of Health dietary supplement fact sheets.

Pamela A. Zinkosky is a freelance writer and avid reader with a passion for telling great stories and learning new things. Her work in journalism and marketing spans topics from health care to business news. She especially loves community history and sees seniors as a valuable source of historical information. Visit www.pazink.net to learn more.