Evidence library

5-HTP

A serotonin precursor with a plausible mechanism and a genuinely limited evidence base. The safety considerations around drug interactions are more firmly established than the clinical benefits.

Ashwagandha

Ashwagandha has the most consistent evidence base of the mainstream adaptogens, with reasonable trial quality for stress and anxiety outcomes. Evidence for other claimed benefits is thinner.

Astaxanthin

A marine carotenoid with the most developed human evidence base among antioxidant supplements for skin ageing and photoprotection. Nine RCTs support modest improvements in skin moisture, elasticity, and wrinkle measures. A smaller cognitive signal exists across four positive RCTs. The evidence is geographically concentrated, largely sponsor-linked, and not independently replicated at scale.

Bacopa Monnieri

Bacopa monnieri is an Ayurvedic herb with the most consistent evidence for improving delayed memory recall in healthy older adults. Trials are small and heterogeneous. Evidence in dementia is insufficient and no guidelines recommend its use.

Berberine

Berberine has a meaningful evidence base for glycaemic control in type 2 diabetes and insulin resistance, but the popular 'natural metformin' framing substantially overstates the evidence. Trial quality is limited, most data come from a single geographic context, long-term safety is not established, and evidence in healthy adults without metabolic indication is absent.

Beta-Alanine

A non-essential amino acid that raises muscle carnosine and improves high-intensity exercise performance in efforts lasting one to four minutes. Evidence is specific to exercise context and dose; general wellness claims are not supported.

Bifidobacterium lactis BB-12

BB-12 is one of the best-studied probiotic strains, with consistent evidence for improving stool frequency and bowel regularity, particularly in older adults and those with low baseline bowel frequency. Effects on immune function and respiratory infections are modest and inconsistent.

Boron

A trace mineral without an established essential function in humans, but with consistent evidence of biological effects in depleted individuals — including improvements in sex hormone profiles, mineral excretion, and cognitive performance. Effects in already-replete populations are smaller and less consistent. Commonly marketed for testosterone support and bone health, but the evidence is primarily from depletion-repletion studies, not supplementation trials in people with normal dietary intake.

Citicoline

Citicoline has a plausible mechanism and some positive trial data for cognitive outcomes, particularly in older adults with mild impairment. Evidence in healthy younger adults is less compelling.

Collagen (Hydrolysed)

Hydrolysed collagen peptides have reasonable evidence for reducing pain and improving function in knee osteoarthritis, distinguishing them from glucosamine and chondroitin where large trials have been negative. Evidence for skin benefits is substantially weaker than marketing suggests — when trials are stratified by funding source, independently-funded studies show no significant effect. Evidence for tendon support in athletes is emerging but currently very low certainty. Dose, timing, and source all matter and are not interchangeable across products.

CoQ10 (Ubiquinone)

CoQ10 has reasonable evidence for specific clinical populations, particularly individuals on statins and those with heart failure. Evidence for broad anti-ageing or energy benefits in healthy adults is not well supported.

Creatine

Creatine has one of the strongest evidence bases in sports nutrition for strength and power output. Emerging evidence for cognitive and healthy ageing applications is plausible but less established.

Curcumin (Standard Extract)

The gap between turmeric's reputation and the evidence for standard curcumin extract is almost entirely a bioavailability problem. The compound shows biological activity in the lab but does not reach meaningful concentrations in the body from conventional supplements.

Curcumin (Enhanced Bioavailability Forms)

Enhanced bioavailability curcumin formulations produce meaningfully different pharmacokinetics than standard extract. The evidence base is more promising but still limited by trial size and duration.

DHEA (Dehydroepiandrosterone)

DHEA is a steroid hormone precursor that declines with age. Intravaginal DHEA has regulatory approval for menopausal dyspareunia. Evidence for oral supplementation is limited and inconsistent across most claimed outcomes.

EGCG (Green Tea Extract)

The primary polyphenol in green tea, with the most marketing claims and one of the more significant supplement safety concerns. Small but consistent weight effects exist in pooled analysis; cancer prevention claims are not supported by RCT evidence; hepatotoxicity at high supplemental doses is well-characterised and has attracted regulatory attention.

Folate and methylfolate

MTHFR status, pregnancy planning, and the distinction between folic acid and methylfolate all matter here. Strong evidence for neural tube defect prevention; more complex picture for other outcomes.

Ginkgo Biloba

Ginkgo biloba is one of the most widely used cognitive supplements globally. Evidence supports modest symptomatic benefit in mild cognitive impairment and early dementia. It does not prevent cognitive decline in healthy older adults.

Glycine

The simplest amino acid, with a small and conflict-of-interest-affected sleep evidence base and growing interest in metabolic and longevity contexts. The GlyNAC combination trials are promising but do not establish glycine-specific effects. Independent replication across all outcome domains is absent.

HMB (Beta-Hydroxy Beta-Methylbutyrate)

HMB shows a modest, consistent signal for lean mass preservation in older adults and catabolic clinical populations. Evidence in trained younger adults is largely negative for body composition. The effect sizes are small and the field has a combination-product attribution problem that complicates conclusions.

Iodine

Iodine is essential for thyroid hormone synthesis and foetal brain development. Deficiency is well-documented in plant-based diets and in pregnancy. The evidence is strong for severe deficiency populations but weaker than often assumed for mild-to-moderate deficiency. Excess intake carries real thyroid risk.

Iron

Iron has strong evidence for correcting iron deficiency and iron-deficiency anaemia, but this effect is strictly dependent on baseline status. Supplementation in iron-replete individuals is not evidence-based and may cause harm.

Inositol

Evidence is strongest for preventing gestational diabetes in high-risk women. PCOS metabolic benefits are real but more limited than commercial messaging implies. Fertility claims extend well beyond what placebo-controlled trials support. Form distinction between myo-inositol and D-chiro-inositol is clinically important.

L-theanine

L-theanine has moderate evidence for modest reduction in acute stress and anxiety in healthy adults, and the caffeine-plus-theanine combination shows consistent benefits for attention and focus. Standalone cognitive enhancement claims are not well supported by the evidence.

Lactobacillus acidophilus

Lactobacillus acidophilus is widely used in probiotic products, but evidence is strain-specific and often comes from multi-strain formulations. No single indication is consistently supported across strains, and broad gut health claims are not well supported.

Lactobacillus rhamnosus GG

Lactobacillus rhamnosus GG is the most broadly evidenced individual probiotic strain, with Strong evidence for antibiotic-associated diarrhoea prevention and acute diarrhoea in children. Evidence for other applications is meaningful but more modest. Strain designation matters -- products labelled Lactobacillus rhamnosus without the GG designation are not equivalent.

Lactobacillus reuteri

Lactobacillus reuteri has meaningful evidence for infant colic, but only in a specific strain and population: DSM 17938 in breastfed infants. Evidence for oral health is promising as an adjunct, while broader gut and immune claims are not well supported.

Lion's Mane

Lion's Mane has a plausible neurotrophic mechanism from preclinical work but human trial evidence is limited to small, short-duration studies in mild cognitive impairment. Claims around neurogenesis, dementia prevention, and cognitive enhancement in healthy adults are not supported by the current human evidence base.

Magnesium

Widespread deficiency in Western populations makes magnesium one of the more defensible supplements. Evidence is strongest for individuals with low status; benefits in replete adults are less clearly established.

NAC (N-Acetylcysteine)

A cysteine derivative and glutathione precursor with strong evidence as a paracetamol antidote and moderate evidence in COPD. Evidence in healthy supplementers remains limited.

Nattokinase

A fibrinolytic enzyme from fermented soybean with a well-characterised mechanism and modest blood pressure evidence across pooled RCTs. Clinical antithrombotic endpoint evidence is absent. Safety concerns around anticoagulant interactions are substantive and documented in case reports — this supplement has a higher clinical risk profile than most in the library.

Nicotinamide Riboside

A vitamin B3 derivative that reliably raises blood NAD+ levels in humans. Despite a plausible mechanism and active research, clinical trials have not demonstrated consistent functional benefits, and an independent systematic review concludes the evidence for clinical effects remains weak.

Nicotinamide Mononucleotide (NMN)

NMN is a precursor to NAD+, a coenzyme that declines with age and plays central roles in energy metabolism and DNA repair. Oral supplementation generally raises blood NAD+ levels in middle-aged and older adults, but this is a biomarker effect. No human trial has yet demonstrated that NMN extends healthy lifespan, prevents disease, or produces clinically meaningful improvements in metabolic or physical outcomes with adequate evidence quality. The IV NAD+ infusion market has outpaced the science considerably.

Omega-3 fatty acids

Omega-3s have strong evidence for triglyceride reduction and specific cardiovascular populations, but the picture for general prevention is more complicated than popular belief suggests.

Panax Ginseng

One of the most globally searched adaptogens, with a modest and inconsistent clinical evidence base across fatigue and cognition. The key interpretive challenge is that most meta-analyses pool across distinct ginseng species, making species-specific conclusions difficult. Evidence is more consistent in disease-affected populations than in healthy individuals.

Phosphatidylserine

Evidence supports modest memory benefits in older adults with cognitive decline, primarily from trials using bovine-derived PS no longer on the market. Soy-derived versions show weaker effects. Cortisol and athletic performance claims rest on very small studies.

Probiotics

Probiotics have genuine evidence for specific indications -- particularly antibiotic-associated diarrhoea prevention and certain IBS applications -- but the evidence is strain-specific and indication-specific. A general probiotic product cannot be assumed to produce the effects demonstrated for a specific studied strain.

Quercetin

The most abundant dietary flavonol, with a large but inconsistent cardiometabolic evidence base. The umbrella review of meta-analyses found effects only on systolic blood pressure and insulin levels, not other cardiovascular biomarkers. The senolytic angle — widely discussed — is based entirely on quercetin combined with dasatinib, not quercetin alone.

Quercetin (Enhanced Bioavailability Forms)

The phospholipid-complexed form of quercetin with substantially higher plasma exposure than standard quercetin. A small Indena-linked clinical programme suggests benefits across allergy, fatigue, and athletic recovery, but all trials are small, sponsor-connected, and independently unverified. Bioavailability advantage is well-established; clinical outcome evidence is not.

Resveratrol

One of the clearest examples of a compound with compelling preclinical data that has not translated to human outcomes. Bioavailability and metabolic instability remain fundamental barriers.

Saccharomyces boulardii

Saccharomyces boulardii CNCM I-745 has strong evidence for preventing antibiotic-associated diarrhoea and remains active during antibiotic treatment. Evidence for acute diarrhoea and H. pylori adjunct use is meaningful but weaker, and broader gut health claims are often overstated.

Vitamin B12

Critical for neurological function and red blood cell formation. Deficiency risk is high in vegans, older adults, and those on metformin. Form and route of administration matter more than is commonly appreciated.

Saffron

A spice-derived extract with the most consistent human evidence for mood in the herbal supplement space. Multiple meta-analyses support efficacy in mild-to-moderate depression and non-inferiority to SSRIs, though most trials are small and geographically concentrated.

Selenium

An essential trace element with well-established roles in thyroid hormone metabolism and antioxidant defence. Evidence supports supplementation in Hashimoto's thyroiditis; evidence in healthy, replete populations is limited.

Taurine

An amino acid with a credible cardiovascular signal and a consumer profile dominated by energy drinks. The evidence is more substantive than the association implies, and more limited than the marketing suggests.

Urolithin A

A gut-derived postbiotic with early human evidence for muscle endurance and mitochondrial support in middle-aged and older adults. All pivotal trials are industry-sponsored and independent replication is lacking.

Vitamin C

Vitamin C has a well-established role in correcting low status, collagen synthesis, and iron absorption. The evidence for cold prevention in ordinary healthy adults is more modest than popular belief suggests. Large prevention trials in replete adults are consistently null for cardiovascular and cancer outcomes.

Vitamin D

Strong evidence for deficiency correction and bone health. Prevention claims for cancer, cardiovascular disease, and cognitive decline in replete populations are not well supported by trial evidence.

Vitamin K2

Vitamin K2 has a plausible and interesting mechanism for directing calcium to bone rather than soft tissue. The human outcome evidence is growing but not yet definitive.

Zinc

Zinc has important biochemical roles in immune processes, wound healing, reproductive health, and skin integrity -- but these do not translate into infection prevention or general immune enhancement in replete adults. The evidence for benefit is clearest in individuals with low or deficient zinc status. Immune boosting and testosterone claims in healthy adults are not well-supported by the trial evidence.