True or False? Separating supplement facts from fiction.

Interest in supplements is increasing every day as more people look for ways to improve their health. In fact, a recent Pew Research Center report said 78% of U.S. adults now take at least one.

Supplement makers’ claims are not always supported by strong evidence. Here are some facts about popular supplements and other products marketed to improve health or performance. Talk with your doctor before starting any supplement.

False. Some supplements can raise your risk of disease. For example, the SELECT trial showed that taking vitamin E to lower the risk of prostate cancer instead raised the risk. It was estimated that in 2013 in the United States, dietary supplements caused 20% of all drug-induced liver injury cases reported to the Drug-Induced Liver Injury Network.

False. Over-the-counter testosterone-boosting supplements are not subject to the same review of their efficacy as prescription drugs. Some supplements have ingredients that decrease levels of testosterone. One study found only 24.8% of commonly used ingredients in these supplements had evidence linked to an increase in testosterone. A little more than half of these ingredients also had conflicting data on if they increased or decreased testosterone.

False. A doctor may prescribe testosterone replacement therapy (TRT) for people diagnosed with a testosterone deficiency. Other ways to increase testosterone include getting quality sleep and resistance exercise. Alternative therapies such as selective estrogen receptor modulators, gonadotropins, and aromatase inhibitors are being explored.

False. Testosterone-boosting supplements are over-the-counter products that claim to boost testosterone naturally. Testosterone replacement therapy is a medical treatment that uses a manufactured form of testosterone and is prescribed by a doctor to treat low testosterone.

True. In men with clinically significant low levels of testosterone (hypotestosteronemia), testosterone replacement therapy may increase bone density, improve erectile dysfunction, increase lean body mass, lead to weight loss, increase strength, and improve mood. Like any other medical treatment, TRT has benefits and risks, and requires monitoring by a qualified health care professional. The degree of improvement will depend on the individual patient.

False. There is not enough evidence to support testosterone screening in men without symptoms, according to the Endocrine Society. Diagnosis of hypotestosteronemia requires low testosterone measurements and physical symptoms from an exam or history conducted by a licensed healthcare professional, according to both the Canadian and American Urological Association. Symptoms can include depression, poor sleep, declining bone and muscle mass, fatigue, and hot flashes.

False. Testosterone replacement therapy is only approved by the FDA for men who have low levels associated with a medical condition, such as genetic or pituitary problems. It is only approved by Health Canada for adult men with medical conditions resulting from an inability to make testosterone.

In June 2026, the FDA requested the removal of warning information stating that the safety and efficacy of testosterone therapy have not been evaluated in men with age-related low testosterone. That update did not change the FDA-approved indication.

Testosterone replacement therapy reduces your body’s ability to make testosterone on its own during treatment.

Possible side effects include acne, prostate stimulation, breast growth or tenderness, worsening sleep apnea, decreased testicular volume, and a decreased sperm count, which can lead to infertility. TRT should be avoided by people with metastatic prostate cancer, untreated obstructive sleep apnea, untreated heart failure, or people who have had a recent heart attack or stroke.

Avoid testosterone replacement therapy if you are trying to conceive children biologically. Raising your amount of serum testosterone through exogenous testosterone leads your hypothalamus to send a signal that ultimately results in inhibiting the release of endogenous hormones responsible for sperm and testosterone production in the testes. This can lead to male infertility.

True. Caffeine has been shown to prevent impaired function in shift workers. Its effects depend on the amount and timing.

False. The FDA and Health Canada agree that 400 mg of caffeine is the maximum amount most healthy adults should consume in a day.

Caffeine also has been associated with significant increases in blood pressure among fire fighters during exercise. The fire fighters in that study consumed, on average, more than 400 mg caffeine, and the increase in blood pressure lasted for at least 19 hours. The study only tested 15 fire fighters and causation was not established.

Excess caffeine can affect sleep, physical health, and mental health in fire fighters.

False. Moderate coffee drinking has been shown to lower the risk of coronary artery disease, stroke, and heart failure. Energy drinks, on the other hand, increase blood pressure, and have been associated with aneurysms, cardiac arrest, dangerous heart rhythms, heart attacks, and tears in major blood vessels and arteries in young and healthy patients.

False. Emergency department visits involving energy drinks have increased over the years. Having an energy drink before exercise can drastically increase your blood pressure.

False. There is insufficient scientific evidence that glutathione can reduce fire fighters’ PFAS levels or protect against oxidative stress from firefighting. The long-term safety of these supplements is unknown. Glutathione is not approved by the FDA or Health Canada to treat fire fighters for occupational exposure.

False. Injectable glutathione products have been recalled multiple times this year. Since July 2026, at least three people have been hospitalized after being injected with contaminated glutathione.

These recalls happen because the produced glutathione is made for dietary supplements, which may not undergo the quality control needed for an injectable drug. Glutathione produced for dietary supplements may contain endotoxins that can cause fevers, inflammatory reactions, and death. Often, the recall occurs after people report negative side effects.

False. Peptides like semaglutide, tirzepatide, and insulin are approved to treat certain medical conditions.

Roughly 11% of all new chemical entities or drugs approved by the FDA from 2016-2024 were peptides. Peptides approved by the FDA or Health Canada undergo large-scale clinical trials that evaluate effectiveness and safety. This approval also means their manufacturing process is highly regulated, so impurities are unlikely.

True. While some peptides, like semaglutide, are approved by the FDA and Health Canada as medications, others, like BPC-157, CJC-1295, TB-500, and GHK-Cu, are not despite being marketed to consumers. Some have shown potential benefits in preclinical studies or in animals, but their safety and effectiveness have not been established in rigorous clinical trials. There is real potential for them to be manufactured with impurities that can hurt you or have unknown safety effects.

Impurities like bacteria can also be introduced during consumer handling, especially when the product is sold as a powder. Unapproved peptides can also affect your immune system, causing reactions like anaphylaxis and hypersensitivity. Determining the safety of a peptide is critical during the approval process.

The immune response can also affect the peptide’s effectiveness. The effect of the immune system on the peptide and on the person taking the peptide is evaluated during a clinical trial. Without clinical trials and regulatory approval, the effect of any peptide on your immune system is unknown. Health Canada has specifically warned against using unauthorized injectable peptides, including BPC-157, CJC-1295, GHK-Cu, and TB-500. Health Canada also warns that unauthorized peptides can increase the risk of kidney damage, blood clots, and tumor growth.

Partially true. In multiple studies, healthy young adults who took creatine and exercised increased muscle strength more than those who exercised without creatine. Randomized controlled trials in older adults have shown that resistance training in combination with creatine supplementation can improve muscle strength, though it did not significantly impact muscle mass and physical function.

False. Current experimental research and clinical evidence does not indicate creatine supplementation leads to dehydration. In fact, a study in 2003 suggests athletes who take creatine had less heat illness and dehydration in hot and humid conditions.

True. Supplement use can be risky for your health. The FDA recommends being cautious of any supplement that claims to prevent disease and advises consumers to talk with their health care team. Health care professionals can help weigh the potential risks and benefits of a supplement.