Nearly 60 percent of Americans say they’ve taken one or more supplements in the past month. For adults 60 and older, that number climbs to 74 percent, according to the Centers for Disease Control and Prevention. And a quarter of people in that group say they’ve used four or more in the past month. Some of them are probably an essential (and doctor-recommended) part of your daily routine: You might take a calcium and vitamin D supplement to keep your bones strong, an iron gummy to ward off the exhaustion that might come with the unlikely appearance of anemia, and a multivitamin—well, just in case. But many other pills, powders, and gummies don’t have much evidence behind them, so you could be paying for something that doesn’t offer the benefits you expect.
Even supplements that are genuinely helpful aren’t covered by the same standards as medications. That means there are virtually no regulations to ensure the safety or efficacy of most of the more than 95,000 supplements on the market.
Many people believe these products as harmless, but that’s a mistake. For starters, you’re not guaranteed to get what’s on the package label. Recent tests by Consumer Reports, for example, found that some supplements containing melatonin, frequently taken as a sleep aid, contain the hormone at levels lower or (more commonly) higher than the dose that’s listed on the bottle.
Beyond getting more or less of an active ingredient than you think you’re getting, many supplements also have potentially serious issues with contamination and quality. Other recent tests have found that unexpired fish oil pills (a popular heart health supplement) are sometimes rancid, and that protein powders and shakes commonly contain lead. More than two-thirds of the protein powders tested contained more lead in a single serving than experts say is safe to have in a day.
Quality control problems aren’t new: A decade ago, a team of researchers reported in Journal of the American Medical Assn. (JAMA) that they’d identified more than a dozen supplements that were adulterated with banned drugs.
Supplements without impurities can come with potential harm too. They can interfere with one’s prescription medicines or affect the results of medical tests. Some ingredients stress the liver and kidneys, which in serious cases may lead to hospitalization—a particular risk for older adults.
So how can you tell which supplements might be both safe and effective? Here’s what to know about the evidence behind some of the most popular pills and the potential risks of others. And remember: Ask your doctor before trying any new supplement to make sure that it’s safe for you.
A Few Supplements to Consider
Although I have previously covered general concepts https://radiantmortontavel.com/2025/08/13/what-everyone-should-know-about-dietary-supplements/ here are a few thoughts about some popular supplements:
Calcium
This mineral is critical to keeping bones healthy and strong. If you don’t regularly consume dairy products or other calcium-rich foods (such as spinach), keeping up with your calcium needs is tricky. Adults should get 1,000 mg of calcium a day; women ages 51 and older and men ages 71 and older need 1,200 mg. But 4 in 10 adults didn’t get that amount, according to a 2024 study in the journal Nutrients. For instance, one cup of whole-milk yogurt contains 300 mg. If you don’t get enough calcium from your diet, your body will pull it from your bones. One widely known consequence of calcium deficiency is osteoporosis (softening of the bones), a disease that raises the risk for bone breaks and fractures. If you’re at risk for osteoporosis (about half of women 50 and older are), if you have osteoporosis, or if you don’t get enough calcium from food, consider a supplement.
But pay attention to the amount: Too much calcium can raise your risk for constipation, kidney problems, and—according to some research—heart attacks. Talk to your doctor about the right dose. You shouldn’t get daily more than 2,500 mg if you’re under age 51; those older should limit their intake to 2,000 mg. Calcium carbonate is generally the most economical type, but if you find it constipating, try calcium citrate.
Iron
Your body needs iron to make hemoglobin, a key protein in red blood cells. Yet 1 in 3 adults are deficient, reports a 2024 study in JAMA Network Open. That can lead to iron-deficiency anemia, a condition where you don’t have enough healthy red blood cells to carry oxygen throughout the body. Without enough oxygen, you can feel tired and irritable. Other symptoms include shortness of breath, brain fog, and dizziness.
Iron is found in both plant and animal foods, such as fortified cereals, beans, poultry, seafood, and meat. But the iron in plant-based sources isn’t absorbed effectively, putting vegans and vegetarians at greater risk for deficiency. Since deficiency is found primarily in menstruating women up to age 50, iron intake requires 18 mg daily; women 51 and older and men require 8 mg. But if you’re getting iron only from plants, you’ll need nearly double that amount. Minor bleeding caused by abnormalities such as ulcers can also deplete one’s iron stores. If you suspect that you might be short on iron, get a blood test to check your level. If you’re deficient, your provider will first seek possible blood loss in hidden areas such as the bowel, and if that is not found, he/she will probably recommend an iron supplement. Don’t consume more than 45 mg of iron a day unless you’re under a doctor’s supervision. Excess iron can cause nausea and diarrhea, and over time, it can damage several organs, although this is rare in adults.
Magnesium
Magnesium gets credited with a host of benefits—improving sleep, relieving constipation, boosting energy, and more. It’s true that magnesium has a widespread impact on one’s health: “Magnesium is involved in muscle contractions, nerve function, energy production, and blood sugar control. Women need 320 mg and men need 420 mg daily. But roughly half of Americans don’t get enough, according to an analysis of 2013 to 2016 data from the National Health and Nutrition Examination Survey.
The best way to get magnesium is through food, such as beans, whole grains, nuts, fruits, and dark leafy greens. (One cup of cooked quinoa has 118 mg of magnesium; 1 ounce of almonds or ½ cup of cooked spinach has 78 mg.) If you’re not getting enough from your diet, a low-dose 200 mg supplement could be helpful. Don’t go higher than 350 mg or you may experience side effects like nausea and stomach discomfort.
Magnesium supplements are generally safe unless you have a kidney issue. They can interact with some medications, including certain antibiotics, biphosphanates (used for osteoporosis), and diuretics. Different types may be better for certain issues: For example, magnesium citrate can help with constipation, while magnesium glycinate is better for sleep and relaxation.
Vitamin D
You need vitamin D to absorb calcium, and it also supports immune function, improves blood sugar, and assists in muscle and brain function. One study suggested that this vitamin, by modifying cell structures, might lengthen longevity, https://radiantmortontavel.com/?p=1086&preview=true, but this remains to be proven
Vitamin D is found in certain foods, such as fortified milk and fatty fish, and people get at least some through sun exposure. Nearly 20 percent of adults between 50 and 79 are deficient in vitamin D, according to a 2023 Frontiers in Nutrition study. A shortage can raise one’s risk of osteoporosis, depression, and issues with blood sugar, but a supplement does not fix all of those issues. Still, people 75 and older and some adults with prediabetes should take a vitamin D supplement (or consume fortified foods), according to the Endocrine Society. Others at risk for osteoporosis or who don’t spend much time in the sun can ask a provider about a blood test.
The recommended daily amount is 600 international units (IU) for adults up to age 70 and 800 IU for those ages 71 and older. Exceeding 4,000 IU daily can be dangerous.
Multivitamins
Nobody has a perfect diet all the time, so taking a multivitamin to fill any vitamin or mineral gaps seems like smart “insurance.” But the science isn’t clear-cut. A number of large-scale studies involving thousands of people haven’t found measurable health benefits from taking a multivitamin. Thus, any benefits that have been found are so minor that routine use of multivitamins is not recommended. On the other hand, newer research suggests that taking a multivitamin may be a good idea for some people—especially for those over 60 or having a an intestinal affliction that interferes with nutrient absorption such as celiac disease. With age, people tend to have less absorption of important nutrients, such as vitamin B12, resulting from decreased appetite. And at least one study found that taking a daily multivitamin was linked to improved memory and slower cognitive aging.
Probiotics
If a healthy gut microbiome (harmless bacterial contents) can lower inflammation and boost immunity—as some research suggests—then getting more probiotics (possessing “good bacteria”) should be helpful. But evidence supporting the routine use of probiotic supplements is weak. However, there are a few instances where doctors may prescribe a specific type of probiotic, such as restore your microbiome after receiving antibiotics. But take caution if you’re buying one off the shelf: Taking the wrong type of probiotic could throw off the equilibrium in your microbiome, causing bloating and stomach issues. Cultured yogurt provides one good source of probiotics.
Vitamin C
Vitamin C helps with iron absorption, collagen production, and immune system function. That’s why one may have been told to load up on vitamin C during cold season. But nearly all Americans—about 94 percent—are not deficient in vitamin C, which comes from foods such as broccoli, citrus, and tomatoes. Getting more than the recommended amount doesn’t do much good, and too much can cause stomachache, diarrhea, and cramps.
Some research suggests that taking a C supplement may shorten the length of severe cold symptoms very slightly (by about a half-day in a three-day illness). But it doesn’t protect against catching a cold or other viruses.
A Few Supplements to Avoid
Kava
Native to Oceania, this plant contains chemicals that are touted to ease stress and anxiety. But a small 2020 study from Australian scientists revealed that kava didn’t receive and benefit for combating anxiety disorders; moreover, people taking the supplement were more likely to have liver issues. As of 2018, there were at least 100 reported cases of liver damage caused by kava. The supplement has been restricted in England and other European countries due to what one paper characterized as “an unacceptable risk” of liver toxicity. Kava also slows the nervous system, so combining it with alcohol or anxiety medications can raise various risks. The Food and Drug Administration has rated the beverage form of kava as “not safe for human consumption.”
Kratom
More than 1 million Americans use kratom, a plant that’s meant to boost energy and mood. Despite the limited evidence and potential risks, it is used to treat pain, anxiety, depression, and more. The FDA issued a warning that people shouldn’t take kratom, but it’s still widely available. Side effects can include agitation, confusion, hypertension, and—in the case of overdoses—seizures and coma. Kratom’s compounds act on the same brain receptors as opioids. In one study of nearly 2,800 people who use kratom, about 1 in 8 qualified as being addicted to it. Thus, it’s best to steer clear of kratom and its synthetic counterpart, 7-OH, which has been linked with overdoses and even death.
St. John’s Wort
Some studies suggest that this herb works similarly to antidepressants. But doctors need to carefully control the dosing on those drugs, which is nearly impossible to do with a supplement, especially when the actual dose can differ from what’s on the label. Most research concludes that St. John’s wort has no benefit at all.
It also interacts with a long list of medications, making them ineffective. These include birth control pills, certain immunosuppressant drugs, and some heart medications such as warfarin. And combining St. John’s wort with selective serotonin reuptake inhibitors (SSRIs)—antidepressants like Prozac—may result in dangerously high serotonin levels. Bottom line: avoid this product!
Green Tea Extract
Green tea has a reputation as a superfood. It’s packed with antioxidants (of unproven value), and it improves alertness—likely due to its caffeine content. As a concentrated supplement, it is also a popular (though largely unproven) weight loss agent. When people drink 12 cups of green tea, it’s spread throughout the day, but with green tea extract, one gets 12 cups worth of tea all at once. At that potentially toxic level, green tea extract can cause digestive issues and interact with medications, including blood thinners and statins for cholesterol. Large doses (800 mg a day and above) can also lead to serious liver injury, another reason to avoid this product!
CONCLUSION
The best advice I can offer is to avoid all supplements unless solid evidence of benefit is provided, given the approval of one’s physician!
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