The Supplements That Could Actually Be Worth Trying

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. (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," says Bess Dawson-Hughes, MD, a professor of medicine at Tufts University School of Medicine in Boston. One widely known consequence of calcium deficiency is osteoporosis, 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.

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 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.

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 as effectively, putting vegans and vegetarians at greater risk for a deficiency. Women up to age 50 need 18 mg of iron a day; 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. Health issues such as ulcers can also deplete your iron stores.

If you suspect that you might be short on iron, "get a blood test to check your level," says Julia Zumpano, RD, a dietitian at the Cleveland Clinic. If you’re deficient, your provider will probably recommend that you try 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 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 your health: "Magnesium is involved in muscle contractions, nerve function, energy production, and blood sugar control," Zumpano says.

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, Zumpano says. Don’t go higher than 350 mg or you may experience side effects like nausea and stomach pain.

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, says Zumpano.

You need vitamin D to absorb calcium. It also supports immune health, improves blood sugar, and assists in muscle and brain function.

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 your 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. But screening for a deficiency is not advised for all adults.

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.

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. David Seres, MD, says that any benefits that have been found are so minor he does not routinely recommend multivitamins.

But newer research suggests that taking a multivitamin may be a good idea for many people—especially if you’re over 60 or you have a condition that interferes with nutrient absorption, such as celiac disease, says JoAnne Manson, MD, professor of medicine at Harvard Medical School in Boston. With age, people tend to have less absorption of important nutrients, such as vitamin B12, and decreased appetite. And a study co-authored by Manson found that taking a daily multivitamin was linked to improved memory and slower cognitive aging.

If a healthy gut microbiome can lower inflammation and boost immunity—as some research suggests—then getting more probiotics (or "good bacteria") should be helpful. But evidence supporting the routine use of probiotic supplements is weak.

There are a few instances where doctors may prescribe a specific type of probiotic, such as to restore your microbiome after a course of 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, says Zumpano.

Vitamin C helps with iron absorption, collagen production, and immune system function. That’s why you 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.

Kava
Native to Oceania, this plant contains chemicals that may ease stress and anxiety. But a small 2020 study from Australian scientists revealed that kava didn’t have any long-term benefits for treating anxiety disorder, and 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 the risk for impairment. The Food and Drug Administration has rated the beverage form of kava as "not safe for human consumption."

More than 1 million Americans use kratom, a plant that’s meant to boost energy and mood. Despite the limited evidence and potential risks, the supplements are 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.

It’s best to steer clear of kratom and its synthetic counterpart, 7-OH, which has been linked with overdoses and even death.

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. Other research concludes that St. John’s wort has no benefit at all.

It also interacts with a long list of medications, "making them ineffective," says Mahtab Jafari, PharmD, of UC Irvine. 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.

Green tea has a reputation as a superfood. It’s packed with antioxidants, and it improves alertness—likely due to the caffeine. As a concentrated supplement, it is also a popular (though largely unproven) weight loss pill. "When people drink 12 cups of green tea, it’s spread throughout the day," says David Seres, MD, of Columbia University Medical Center. "But with green tea extract, you’re getting 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 lead to serious liver injury.

Protein powders and shakes are popular, but many are also prone to serious heavy metal contamination, according to our investigation, "Protein Powders and Shakes Contain High Levels of Lead"—and for most people, they’re simply not needed.

The average adult should get 0.36 gram of protein per pound of body weight, which comes to 54 grams for a 150-pound person. That’s roughly the amount in one small cooked chicken breast or 2 cups of low-fat Greek yogurt. People older than 65 need about 50 percent more.

It’s critical to do your research: CR’s testing of 23 protein powders and shakes found that more than two-thirds of them had lead levels that exceeded our level of concern. Those with pea protein as a main ingredient were especially worrisome.

See our full findings.