OTC Supplements

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme in every cell. It carries electrons in energy metabolism and is used up by sirtuins, PARPs and CD38. Clinics sell it as an intravenous drip, but no trial has tested NAD+ infusions for any health outcome. In a small study, infused NAD+ disappeared from the blood for the first 2 hours. Most human data come from its oral precursors NR and NMN. They reliably raise NAD+, but their effects on health outcomes are mixed and often null.

Lithium orotate is a lithium salt sold over the counter as a low-dose supplement, far below the doses of prescription lithium carbonate. Interest rose after a 2025 Nature study that restored brain lithium with lithium orotate in mice and prevented Alzheimer-like changes. There are no controlled human trials of lithium orotate itself. Whether the orotate salt behaves differently from other lithium salts is disputed.

Magnesium is an essential mineral sold in many salt forms. Meta-analyses of randomized trials find modest drops in blood pressure, largest in people with hypertension or low magnesium. They also find improved insulin resistance with longer use and fewer migraine attacks. Evidence for sleep and depression is weaker but positive. Citrate, chloride, lactate and aspartate are generally absorbed more completely than oxide, but head-to-head results conflict and better absorption has rarely translated into better clinical outcomes.

Acetyl-L-carnitine (ALCAR) is the acetyl ester of L-carnitine and the body's main carnitine ester. It is sold as a supplement and, in some countries, as a prescription drug. Meta-analyses find that it eases depressive symptoms, mostly in older adults and across small, inconsistent trials, and that it reduces diabetic nerve pain at doses above 1.5 g a day, on very low-certainty evidence. It did not slow Alzheimer's disease in two year-long trials, and it made chemotherapy nerve damage worse in a large one.

Creatine is one of the most researched sports supplements. It is best known for building strength and muscle, and is increasingly studied for the brain. Meta-analyses of randomized trials find small-to-moderate improvements in memory, attention and processing speed. The effects on memory are largest in older adults. It is well tolerated at 3 to 5 g a day.

DL-phenylalanine (DLPA) is a 50:50 mix of the dietary amino acid L-phenylalanine and its mirror image, D-phenylalanine. It is sold for mood and pain on the strength of two 1970s–80s ideas: that L-phenylalanine feeds catecholamine and phenylethylamine synthesis, and that D-phenylalanine slows the breakdown of enkephalins. The human evidence is old and thin. Small German depression studies were positive but had no placebo arm, and the only placebo-controlled chronic-pain trial of D-phenylalanine found no analgesic effect. The strongest modern data concern L-phenylalanine alone: short-term tolerability up to 12 g/day in healthy men and gut-hormone effects at 10 g.

L-theanine is an amino acid found almost only in tea. Taken at 200 to 400 mg a day, it may reduce stress and anxiety in people under stressful conditions. Its best-known use is alongside caffeine, where the pair improves attention switching more than either alone. A 2025 meta-analysis found small improvements in subjective sleep.

L-tyrosine is a dietary amino acid and catecholamine precursor, not a reliably demonstrated everyday nootropic. Small crossover trials suggest that large acute doses can preserve selected attention, working-memory or psychomotor outcomes during sleep loss, cold, noise or demanding multitasking, but reviews judge the evidence heterogeneous and too weak for a firm recommendation. Results in unstressed adults are mixed and baseline-dependent. A meta-analysis found no endurance benefit, although one later 12-person cycling experiment was positive. Four weeks at up to 4 g/day produced no dose-related safety signal in 30 healthy men, but that does not establish long-term or clinical-population safety.

N-acetyl-L-tyrosine (NALT) is a water-soluble acetylated derivative of L-tyrosine. Human evidence is almost entirely intravenous nutrition research, where 35–60% was recovered unchanged in urine and plasma tyrosine often did not rise. There are no cited human oral trials showing that NALT improves cognition, stress performance or energy.

N-acetylcysteine (NAC) is an acetylated form of the amino acid cysteine. It is the standard antidote for acetaminophen (acetaminophen) overdose, a mucolytic that modestly cuts flare-ups of COPD and chronic bronchitis, and a widely sold supplement. Its psychiatric uses rest on a mixed record: a positive trial in adolescents who used cannabis failed to repeat in adults, and large trials found no benefit for idiopathic pulmonary fibrosis or for protecting the kidneys during angiography. Only about a tenth of an oral dose reaches the blood.

Alpha-lipoic acid (ALA) is a sulfur-containing mitochondrial cofactor, used as a racemic drug for the pain and pins-and-needles of diabetic nerve damage. Meta-analyses of randomized trials support it for diabetic neuropathy symptoms. Its effects on weight and blood sugar are real but small. Supplements come as the racemic mix, as pure R-ALA, or as Na-R-ALA, a sodium salt of R-ALA made to absorb better.

Astaxanthin is the red carotenoid that colors salmon, shrimp and crayfish. Supplements usually contain an extract of the microalga Haematococcus pluvialis. It is sold as a very strong antioxidant, and pooled trials do show a modest fall in the lipid-peroxidation marker malondialdehyde. The effects that matter clinically are small or inconsistent. Meta-analyses find a little more skin moisture and elasticity but no change in wrinkle depth, no reliable effect on blood lipids or blood pressure in the general population, and no gain in endurance performance. Its safety at up to 8 mg a day is well studied.

Coenzyme Q10 (CoQ10) is part of the mitochondrial energy chain and one of the most widely used supplements. Its best evidence is in chronic heart failure. There, the Q-SYMBIO trial found fewer major cardiovascular events and deaths over two years. For statin muscle pain, migraine and blood pressure, the results are mixed or modest.

Myricetin is a flavonol found in berries, vegetables, tea and wine. It is studied for glucose regulation, mitochondrial function and neuroprotection, but the evidence for the isolated molecule remains preclinical. Small human trials have used blends containing myricetin; none separates its contribution from the other ingredients.

PQQ (pyrroloquinoline quinone) is a redox cofactor first found in bacteria. Mammals do not make it but take in trace amounts from food. In cells it switches on mitochondrial biogenesis through the PGC-1α pathway. In humans, small 12-week trials of PQQ disodium salt reported better memory and attention scores.

S-acetylglutathione (SAG) is glutathione with an acetyl group attached to its sulfur. It is sold as a supplement on the idea that it survives digestion better than plain glutathione. In the only human pharmacokinetic study, a 3.5 g dose produced no detectable SAG in the blood, and the rise in blood glutathione looked much like the rise after plain glutathione. Every other result comes from cells, animals, or one small open-label trial of a multi-ingredient product. EFSA judged it safe as a food at up to 300 mg a day for adults.

Ubiquinol is the reduced, electron-carrying form of coenzyme-q10, sold as a better-absorbed version. One small study found it raised blood CoQ10 more than ubiquinone. A randomized crossover study in older adults found no significant difference. Its most notable trial is in multiple-system atrophy, where high doses improved a motor score.

Urolithin A is not something plants make. It is what some people's gut bacteria make out of the ellagitannins in pomegranates, walnuts and berries, and only about one person in seven produces enough of it to show up in blood without a supplement. Synthetic urolithin A was identified as the first natural compound to induce mitophagy — the pathway that clears worn-out mitochondria. Four randomized trials have now tested it in people. The two muscle trials both missed their primary endpoint and both reported gains on secondary measures; a 2025 trial found changes in T-cell composition and metabolism; and a trial in trained runners found no performance benefit.

Urolithin B is a gut microbial metabolite of dietary ellagitannins, studied for muscle growth and protection against muscle wasting. It increased muscle size and reduced denervation-induced atrophy in mice. A 2026 study found distinct effects on gene expression in cultured human muscle cells, but did not test a supplement in people. Its muscle evidence remains preclinical; it is not interchangeable with urolithin-a.

Fish oil supplies the two long-chain marine omega-3 fatty acids EPA and DHA. Its best-established effect is on triglycerides: high-quality evidence puts the reduction at roughly 15%, dose-dependently, and prescription formulations at 4 g a day are licensed drugs for severe hypertriglyceridemia. What it does not do is what most people buy it for. A Cochrane review of 79 trials in 112,059 people found little or no effect of EPA and DHA on all-cause mortality, cardiovascular mortality or cardiovascular events, and the three largest modern supplement trials — VITAL, ASCEND and STRENGTH — were all null.

Alpha-GPC (choline alfoscerate) is a choline-containing phospholipid breakdown product, sold as a prescription drug in some countries and a supplement elsewhere. It is a precursor of both choline and acetylcholine. Its record is unusually mixed. One very large Korean cohort linked it to lower dementia conversion, while another linked it to higher 10-year stroke risk.

Caffeine is the world's most widely used psychoactive compound, a methylxanthine that works by blocking adenosine receptors. At low to moderate doses it reliably improves alertness, vigilance, attention and reaction time, with weaker and less consistent effects on memory and higher-order judgment. It is the reference point every other stimulant on this wiki gets compared to.

Citicoline (CDP-choline) is an intermediate in the synthesis of phosphatidylcholine, the main phospholipid in cell membranes. It is a prescription drug in some countries and a supplement in others. A meta-analysis found it improved cognitive status in mild cognitive impairment, Alzheimer's disease and post-stroke dementia, though the underlying studies were of poor quality.

Melatonin is the hormone the pineal gland releases at night to signal darkness. Taken as a supplement, its most convincing use is jet lag, where a Cochrane review put the number needed to treat at 2. For insomnia the benefit is real but modest: about 7 minutes faster sleep onset and 8 minutes more sleep on average. Timing matters as much as dose.

Paraxanthine (1,7-dimethylxanthine) is what most caffeine turns into in the body: about 80% of a caffeine dose is converted to it. Like caffeine it blocks adenosine receptors, and at 4 mg/kg it raised diastolic blood pressure and adrenaline in people about as much as the same dose of caffeine. It is now sold on its own as a supplement. Small crossover trials funded by the ingredient's sponsor report better scores on some attention, memory and reaction-time tests after 50 to 200 mg, though their main statistical tests were not significant.

Phosphatidylserine (PS) is a membrane phospholipid sold for memory. The strongest early trial used PS extracted from cow brain, in 494 elderly patients with cognitive decline. Soy-derived PS, developed as an alternative to bovine PS, has smaller trials showing memory gains in older adults with memory complaints. Smaller studies suggest it blunts the cortisol response to stress.

Uridine monophosphate (UMP) is a nucleotide and dietary source of uridine, one of the precursors used to make phosphatidylcholine and other neuronal membrane phospholipids. In rodents, UMP raises brain phosphatides and can increase striatal acetylcholine release; after six weeks it also increased potassium-evoked, but not basal, striatal dopamine release in aged rats. Human cognitive evidence does not isolate UMP: the trials used it inside a multinutrient drink with choline, DHA, EPA, phospholipids, vitamins and selenium, and the primary cognitive outcomes were mixed.

Ashwagandha (Withania somnifera) extracts have modest human trial evidence for perceived stress and sleep, although pooled results differ by outcome and trial quality is mixed. KSM-66, a root-only extract standardized to at least 5% withanolides, is used in several well-known trials. Extract names and standardization measures matter: their trial results are not automatically interchangeable.

Bacopa monnieri is an Ayurvedic herb used traditionally to support memory. Randomized trials in healthy older adults found better verbal learning and delayed recall after about 12 weeks. A meta-analysis of nine trials found faster attention (Trail B) and choice reaction time. It is slow to act and commonly causes gut side effects.

Citrus bergamot is a flavonoid-rich extract of the bergamot orange, sold to lower cholesterol. Several small randomized trials found lower LDL cholesterol. A 2026 meta-analysis of nine trials found modest improvements in blood pressure, glucose and insulin resistance, and rated trial results as inconsistent. A network meta-analysis ranked it among the most effective LDL-lowering nutraceuticals.

Sabroxy is a branded bark extract of Oroxylum indicum, the Indian trumpet tree. It is standardized to three flavones: oroxylin A, chrysin and baicalein. One 12-week randomized trial in older adults with memory complaints found better episodic memory than placebo. The same trial found no difference on most individual tests, the MoCA or self-rated cognition. That trial is the only controlled human study of the plant.

Saffron is the dried stigma of Crocus sativus; supplements usually contain extracts with several constituents rather than a single molecule. Human trials suggest benefits for mood and subjective sleep quality, but a 2026 meta-analysis found improvements on self-rated depression and anxiety scales without significant effects on Hamilton depression or anxiety ratings or overall mood scores. Results depend on the preparation and outcome measured. Trials of the branded extract affron mostly report modest gains on self-rated depression scores, but a 2021 EFSA review judged its mood evidence insufficient for a health claim.