The honest answer to "which supplements actually work" is a short list, not a long one. Most of the pills, powders and gummies on the shelf have little good evidence behind them, and a handful — calcium and iron among them — are genuinely useful in specific situations. That is the finding shape that runs through careful consumer-health reporting on the category, including a recent Consumer Reports review of which supplements could be worth trying.
The scale of the habit is large. According to Consumer Reports, nearly 60 percent of Americans say they have taken one or more supplements in the past month, and among adults 60 and older the figure reaches 74 percent, citing the Centers for Disease Control and Prevention. A quarter of that older group reports using four or more in a month. Spending that size deserves a clear-eyed look at what earns its place.
Shape first, blame last, as a coach would say. The problem is not that people are careless. It is that the market makes careful choices hard, and the evidence is thinner than the labels suggest.
Why is the supplement shelf so hard to judge?
Because supplements are regulated differently from drugs, and the difference is bigger than most shoppers realise. Consumer Reports notes there are virtually no regulations to ensure the safety or efficacy of most of the more than 95,000 supplements on the market. A drug has to prove it works before it is sold. A supplement generally does not.
The practical consequence is that the label is a claim, not a guarantee. "You're not guaranteed to get what's on the package label," Mahtab Jafari, a professor of pharmaceutical sciences who studies supplement safety at the University of California, Irvine, told Consumer Reports. For anyone trying to sort evidence from marketing, that single sentence explains most of the confusion. Our guide to how dietary supplements are actually regulated covers the mechanics in more detail.
Does calcium earn its place in the cabinet?
For people who do not get enough from food, yes — with real caveats. Calcium is critical to keeping bones healthy and strong, and Consumer Reports reports that 4 in 10 adults did not meet their daily calcium needs, according to a 2024 study in the journal Nutrients. Adults should get 1,000 mg a day, rising to 1,200 mg for women 51 and older and men 71 and older; one cup of whole-milk yogurt contains 300 mg.
The mechanism is plain. "If you don't get enough calcium from your diet, your body will pull it from your bones," Bess Dawson-Hughes, a professor of medicine at Tufts University School of Medicine, told Consumer Reports. Osteoporosis — a disease that raises the risk of breaks and fractures — is the best-known consequence, and about half of women 50 and older are at risk for it.
What this means is that calcium is a gap-filler, not a booster. It works where diet falls short. Too much brings its own risks: Consumer Reports flags constipation, kidney problems and, according to some research, heart attacks, and notes upper intake limits of 2,500 mg a day for those under 51 and 2,000 mg for anyone older. Those are attributed safety facts, not a personal recommendation — the right dose is a conversation with a doctor.
What about iron?
Iron is the clearest case of a supplement fixing a diagnosed problem. The body needs iron to make hemoglobin, the protein in red blood cells that carries oxygen, and a 2024 study in JAMA Network Open found 1 in 3 adults are deficient, as reported by Consumer Reports. Short on oxygen, people feel tired and irritable; shortness of breath, brain fog and dizziness can follow.
Diet matters here. Iron is found in fortified cereals, beans, poultry, seafood and meat, but the iron in plant sources is not absorbed as effectively, which puts vegans and vegetarians at greater risk. Women up to 50 need 18 mg a day and men 8 mg, per the figures Consumer Reports cites, with plant-based eaters needing nearly double.
The useful detail is the testing step. "Get a blood test to check your level," Julia Zumpano, a dietitian at the Cleveland Clinic, told Consumer Reports. Supplementing an unconfirmed deficiency is guesswork, and excess iron can cause nausea and diarrhea and, over time, damage organs. Consumer Reports notes a ceiling of 45 mg a day without medical supervision. Iron, like calcium, is treatment for a measured gap — not a general tonic.
What this means: the quality problem nobody sees
Here is the part that changes how the whole shelf should be read. Even the well-supported supplements only work if the product contains what it says. Consumer Reports' own testing found melatonin products frequently containing more — or sometimes less — of the hormone than the label lists. Unexpired fish oil pills were sometimes rancid. And more than two-thirds of the protein powders Consumer Reports tested contained more lead in a single serving than its experts say is safe for a day. Our coverage of heavy metals in protein powders looks at that testing in detail. Readers following this should also see Heavy metals in protein powders: what the testing found.
This is not a new problem either. Consumer Reports points to research published in JAMA a decade ago in which researchers identified more than a dozen supplements adulterated with banned drugs. "Many people think of these products as harmless, but that's a mistake," David Seres, a professor of medicine at Columbia University Medical Center, told the publication.
Our analysis: the ranking that matters is two-stage, not one. First, does the ingredient have evidence? Second, does the specific product deliver it cleanly? The first question gets most of the attention. The second decides whether the first one means anything, which is why third-party certification and knowing how to spot a low-quality supplement before you buy belong in the same conversation as the ingredient list.
So which supplements are worth the money?
The evidence supports a narrow reading. Calcium and iron are worth considering when diet or a blood test shows a genuine gap, and Consumer Reports counts them among the supplements that could be worth trying. Beyond those, the honest verdict for many cabinet staples is that no good evidence supports the claims on the label — and that is a finding in its own right, not a gap in coverage.
What remains unknown is product-level. The evidence base tells you an ingredient can work; it cannot tell you the bottle in front of you does what it says. Consumer Reports also notes supplements can interfere with prescription medicines or affect medical test results, and that some ingredients can tax the liver and kidneys — a particular risk for older adults, Jafari said. That is the strongest argument for involving a doctor before anything new goes in the basket. The cabinet, like a squad, should be built on evidence, not on hope for the highlight reel.
