What the supplements actually have behind them.

The most studied sports supplement there is. It reliably adds a small amount of lean mass and strength on top of resistance training, and newer trials suggest a modest effect on memory, clearest in older adults.

Essential, and easy to be low in. Supplements reliably raise blood levels and treat deficiency. In the largest trials, giving it to adults who were not deficient did not prevent cancer, heart disease or fractures.

An essential mineral sold for sleep, stress, blood pressure and blood sugar. Trials show a small, real effect on blood pressure and on glucose in people at risk of diabetes. The sleep evidence is thin and of low quality.

Fish oil for the heart is one of the most tested ideas in nutrition, and the large trials disagree. Ordinary supplement doses did not prevent heart disease in the general population; one high-dose prescription product did in high-risk patients, and a near-identical trial did not.

A concentrated milk protein. Adding it to resistance training produces a small, repeatable gain in strength and lean mass, which stops growing once total daily protein is already high. On its own, without training, it builds nothing.

The most widely used stimulant on earth and the best-evidenced performance aid in sport. It reliably improves endurance, strength and power by a few percent. The cost, measured just as carefully, is sleep, even when taken in the afternoon.

The body's own darkness signal, sold as a sleep aid. It shifts the body clock reliably and nudges sleep onset by minutes, not hours. For chronic insomnia in adults the meta-analyses disagree, and the common dose and timing may be the wrong ones.

A root extract from Ayurvedic tradition, sold for stress, sleep, testosterone and strength. Small, mostly manufacturer-funded trials report large effects on anxiety. Case series from three continents document liver injury, with deaths in people who already had liver disease.

An essential mineral, and the most argued-over cold remedy in the literature. High-dose zinc acetate lozenges shortened colds by days in some trials, a 2020 trial of a commercial lozenge found nothing, and the 2024 Cochrane review calls the evidence uncertain.

Broken-down animal collagen sold for skin, joints and tendons. Meta-analyses of mostly manufacturer-funded trials report improved skin hydration and elasticity and reduced osteoarthritis symptoms. Independent trials are few and the certainty of evidence is low.

A plant alkaloid from traditional Chinese medicine with a real glucose-lowering effect in type 2 diabetes, shown in dozens of trials including a large multicenter one. Sold online as nature's Ozempic, which it is not: the trials are about blood sugar, not weight loss.

A licensed hospital drug for paracetamol overdose and mucus, sold online as an antioxidant for everything. Meta-analyses support fewer flare-ups in chronic bronchitis and COPD. In psychiatry the trials point different ways, clearest in schizophrenia and weakest in depression.

A molecule every cell uses to make energy, sold for heart failure, statin muscle pain and fatigue. One heart failure trial found fewer deaths; the Cochrane review is not convinced. A meta-analysis found relief of statin muscle symptoms; a trial found no metabolic benefit.

Live bacteria or yeast taken for gut health. For one use, preventing diarrhea when taking antibiotics, the evidence is large and consistent. For irritable bowel the evidence is strain-specific and mostly low certainty. For general wellness in healthy people there is little.

An amino acid that raises muscle carnosine, a buffer against the acid that builds up in hard efforts lasting one to ten minutes. Forty trials find a small, real effect in that window and none outside it. The tingling it causes is harmless and well documented.

Oil of Nigella sativa seeds, with 82 randomized trials behind it, mostly small and short. Pooled, they show modest drops in blood pressure, fasting glucose, LDL and weight. An umbrella review graded almost all of that evidence low or very low, which is the honest state of it.

A tar-like resin from Himalayan rock, used in Ayurveda for centuries. One small 90-day trial raised testosterone in men aged 45 to 55; one 8-week trial reduced strength loss after fatigue. Both used the same purified extract. Raw resin has tested over heavy-metal limits.

The hydrochloride salt of creatine, sold on better solubility and a smaller dose. It dissolves better; whether that matters is the question. Two small trials against monohydrate point opposite ways, and nobody has shown it raises muscle creatine more than the cheap form.

On this shelf because of zinc. High-dose zinc blocks copper absorption; the deficiency that follows brings anemia, low white cells and nerve damage that may not reverse. Audits find most zinc patients never get checked. Whether a healthy man needs extra copper is another matter.

A Southeast Asian root sold to men for testosterone. Five small trials pooled show testosterone rising; two erection trials pooled show nothing. EFSA declined to clear the extract after a DNA-damage signal, and 26% of Malaysian products once tested over the mercury limit.

A kitchen spice whose seed extracts are sold to men for testosterone. Seven trials pooled show a small rise in total testosterone (SMD 0.32), most of it from branded extracts with manufacturer involvement. The better-founded effect is on blood sugar in people with diabetes.

A Nigerian shrub sold to men on the strength of a 2005 rat study. There is no human trial of any kind. The same rat lab found testicular changes at every dose after 28 days and membrane damage in liver and kidney. It is here so nobody has to find that out after buying it.

The most-tested herbal for an enlarged prostate, and the clearest case here of early trials being overturned. Two large NIH trials and Cochrane found no benefit over placebo, even at triple dose. One European pharmaceutical extract still pools positive. Safe either way.

An Andean root sold for libido and fertility. Small trials find it raises sexual desire without touching testosterone, a 2.4 g dose gave mild ED a 1.6-point IIEF-5 gain, and the semen trials are suggestive but thin. It does whatever it does without being a hormone.

The best-studied herb in the world and still unsettled. Cochrane found a trivial effect on erectile function. Pooled trials find memory up a little and fatigue modestly better. An umbrella review rated 14 of 19 meta-analyses critically low. Safe at usual doses.

The yellow in turmeric, with a meta-analysis of 11 meta-analyses behind it for knee osteoarthritis pain and function. Pooled trials also find lower CRP and faster recovery from muscle damage. Poorly absorbed, and the US liver-injury network is logging cases.

An arctic root sold for fatigue and stress. A 2012 review found 11 controlled trials, contradictory, all at high or unclear risk of bias. The best, 60 people with burnout over 28 days, found less fatigue than placebo. It slows a liver enzyme that clears warfarin.