Nutrition

Alpha-lipoic acid (ALA) is a sulfur-containing fatty acid serving as an essential cofactor for two mitochondrial enzyme complexes — pyruvate dehydrogenase and α-ketoglutarate dehydrogenase — linking glycolysis to the citric acid cycle. Only the R-enantiomer (R-ALA) is protein-bound and biologically active; commercial supplements contain a racemic R/S mixture, and oral bioavailability of R-ALA is ~40–50% greater than the S form. ALA and its reduced metabolite dihydrolipoic acid (DHLA) are lipid- and water-soluble, enabling free-radical scavenging across cellular compartments and regeneration of oxidized glutathione, vitamin C, and vitamin E — a recycling cascade distinguishing ALA from single-compartment antioxidants. Mitochondrial function and endogenous glutathione decline with aging; ALA partially restored both in rodent models, though direct evidence in humans is limited. The strongest clinical evidence concerns diabetic polyneuropathy: the SYDNEY trial (Ametov et al., 2003, n=120) found intravenous ALA at 600 mg/day over three weeks significantly reduced neuropathic symptom scores versus placebo (p<0.001). The four-year randomized NATHAN 1 trial (Ziegler et al., 2011, n=460) tested oral ALA 600 mg/day; the primary composite endpoint (NIS-Lower Limbs plus seven neurophysiologic tests) did not reach significance (p=0.105), though secondary scores (NIS, NIS-LL) favoured ALA. In healthy aging populations evidence is preliminary and largely confined to animal or small mechanistic studies; long-term longevity benefit in humans has not been established.

Apigenin is a plant flavone found in parsley, celery, chamomile and dried oregano. In a 2013 Diabetes paper, Escande and colleagues identified apigenin as an inhibitor of the NAD+-consuming ectoenzyme CD38; oral apigenin in obese mice raised tissue NAD+ levels and improved glucose and lipid handling, which prompted its promotion as an NAD+-boosting supplement. Human data are very limited: bioavailability after oral intake is low, plasma half-life short and no adequately powered randomised trial has demonstrated metabolic or longevity-relevant endpoints. Apigenin from typical food intake is unlikely to reach the doses used in rodent studies. There is no EU-authorised health claim for apigenin.

Astaxanthin is a ketocarotenoid pigment produced predominantly by the microalga Haematococcus pluvialis and accumulated through the food chain in crustaceans, salmon, and trout, accounting for their characteristic pink-red coloration. Its molecular structure — a polyene chain with carbonyl and hydroxyl groups on both ionone rings — enables it to span the full width of the lipid bilayer and scavenge singlet oxygen and free radicals; in vitro, astaxanthin shows higher singlet-oxygen quenching than many other carotenoids, including β-carotene. Unlike certain antioxidants, it does not act as a pro-oxidant at high concentrations under physiological conditions. Proposed mechanisms relevant to longevity include Nrf2 activation, NF-κB inhibition, mitochondrial protection, and modulation of inflammatory cytokines. Rodent studies show improvements in oxidative stress, immune parameters, and some cardiovascular markers; human RCTs are small and generally short-term, reporting modest effects on lipid oxidation biomarkers, skin aging, exercise-induced muscle damage, and inflammation. Synthetic astaxanthin (dominant in aquaculture) and natural algal-derived forms differ in esterification and stereochemistry, which may affect bioavailability. Evidence for direct human longevity benefit remains preliminary.

Blue Zones are regions reported to have unusually many centenarians. The popularly cited list (Buettner) includes Okinawa (Japan), Sardinia (Italy), Nicoya (Costa Rica), Ikaria (Greece), and Loma Linda (USA). Shared features include plant-based diets, moderate caloric intake, low-intensity movement, strong social ties, and purpose. Saul Newman has argued that supercentenarian counts may be inflated by age-record errors, pension fraud, and missing birth registries; this methodological critique was recognised when Newman was awarded the 2024 Ig Nobel Prize in Demography for the work, and the demographic robustness of the original Blue Zone identifications is now contested.

The branched-chain amino acids leucine, isoleucine and valine are essential amino acids enriched in meat, dairy, eggs and protein supplements. Leucine in particular is a potent activator of mTORC1 and stimulates skeletal-muscle protein synthesis, a basis for BCAA supplementation in athletic and clinical sarcopenia contexts. Counterbalancing this, observational human studies and rodent work link elevated circulating or dietary BCAAs to insulin resistance and type 2 diabetes risk; in mice, Solon-Biet et al. (2019, Nature Metabolism) showed that chronic high-BCAA diets shorten lifespan indirectly through amino-acid imbalance and hyperphagia rather than intrinsic toxicity. BCAA balance, not absolute intake, drives the metabolic phenotype, and there is no EU health claim for BCAA supplementation.

Caffeine is a methylxanthine alkaloid found in coffee, tea, and cocoa that acts as a competitive antagonist of adenosine A1 and A2A receptors, inhibiting the adenosine-mediated signalling that promotes drowsiness and reduces neuronal activity. Receptor blockade disinhibits dopamine, glutamate, and acetylcholine release, producing increases in alertness, reaction time, and sustained attention. Plasma half-life averages 5–6 hours in healthy adults but extends with age, liver impairment, or oral contraceptive use, so a late-afternoon dose can suppress slow-wave and REM sleep. Habitual coffee consumption shows an inverse association with all-cause mortality: the NIH-AARP Diet and Health Study (Freedman et al. 2012, N ≈ 400,000) found 4–5 cups/day associated with hazard ratios of ~0.88 (men) and ~0.84 (women), with reduced risk across cardiovascular, respiratory, stroke, diabetes, and infection-related causes; a meta-analysis of 23 prospective studies (Malerba et al. 2013) corroborated an inverse trend at moderate intake. A2A antagonism is linked to lower Parkinson's disease incidence in prospective data and underpins the approved drug istradefylline, though caffeine is neither approved as a therapeutic nor proven causally protective — residual lifestyle confounding cannot be excluded. A 2025 narrative review (Carbone et al.) notes moderate intake may support alertness and offer neuroprotective effects in aging, while excessive use can cause anxiety, sleep disturbances, and cognitive or motor impairment in older adults.

Carnosine is a dipeptide of beta-alanine and L-histidine, concentrated in skeletal muscle and nervous tissue. It operates through four mechanisms: intracellular pH buffering during high-intensity exercise, reactive carbonyl scavenging (trapping aldehydes before protein crosslinking occurs), chelation of redox-active ions such as copper(II) and zinc(II), and quenching of reactive oxygen species. In geroscience, its anti-glycation activity is particularly relevant: carnosine inhibits the formation of advanced glycation end products (AGEs), protein-sugar adducts that accumulate in aged tissue and promote vascular and neurological damage. Intramuscular carnosine declines by approximately 47–63% between early adulthood and the seventh decade — with the steeper losses in fast-twitch type II fibers. A double-blind, placebo-controlled RCT (Houjeghani 2018; n = 54 adults with type 2 diabetes) found that 12 weeks of oral L-carnosine (1 g/day) significantly reduced serum AGEs and TNF-α versus placebo. Long-duration trials in healthy older adults remain absent; most human data derive from short trials in metabolically compromised populations, and the degree to which oral supplementation raises tissue carnosine — given rapid hydrolysis by serum carnosinase — is an active research question.

Choline is a water-soluble nutrient officially recognised as essential by the US Institute of Medicine in 1998, which set Adequate Intakes of 425 mg/day for adult women and 550 mg/day for adult men; EFSA set a uniform Adequate Intake of 400 mg/day for adults in 2016. Choline is the backbone of phosphatidylcholine and sphingomyelin, a precursor of the neurotransmitter acetylcholine, and a methyl-group donor via oxidation to betaine. The richest dietary sources are egg yolk, liver, soybeans and beef. In the colon, microbial enzymes convert excess choline and phosphatidylcholine to trimethylamine (TMA), which the liver oxidises to TMAO; elevated TMAO has been associated with cardiovascular risk in observational studies, though causality in humans remains debated.

Coenzyme Q10 (ubiquinone) is a lipid-soluble molecule essential for mitochondrial electron transport and ATP production, and an intracellular antioxidant. Endogenous levels decline with age and with statin use. Clinical evidence is strongest in heart failure: in the Q-SYMBIO trial (300 mg/day), CoQ10 reduced all-cause mortality and major cardiovascular events in chronic heart failure patients; however, replication has been inconsistent and most other trials have been smaller. Effects on blood pressure and statin-related muscle symptoms are modest; longevity benefits in healthy adults are not established.

Collagen peptides, also called hydrolysed collagen or collagen hydrolysate, are produced by enzymatic hydrolysis of animal collagen (typically bovine, porcine or fish skin and bone) to fragments of about 2-5 kDa. Iwai and colleagues (2005) demonstrated that hydroxyproline-containing dipeptides, notably Pro-Hyp and Hyp-Gly, appear in human plasma after oral ingestion, providing evidence for absorption beyond free amino acids. Randomised trials of 2.5-10 g per day for 8-24 weeks show modest improvements in skin hydration and elasticity, and meta-analyses report pain reduction in knee osteoarthritis. Effects on bone mineral density and tendon healing are less consistent. Collagen peptides are regulated as food in the EU and have no EU-authorised health claim.

Creatine is a guanidino compound synthesized endogenously in liver and kidney from arginine, glycine, and methionine, and obtained exogenously from red meat, fish, and supplements. As phosphocreatine, it rapidly regenerates ATP from ADP via the creatine kinase reaction during high-intensity efforts, buffering energy supply in muscle and brain. Creatine monohydrate supplementation (3–5 g/day after an optional loading phase) is one of the most extensively validated ergogenic aids, consistently increasing lean mass and strength in resistance-trained adults across meta-analyses. Emerging evidence in older adults indicates additional benefits on muscle preservation and fall prevention, with some RCTs and meta-analyses also suggesting modest cognitive effects — particularly relevant because older adults have lower dietary creatine intake and endogenous synthesis declines. Safety at habitual supplementation doses is well established in healthy adults; data on safety in chronic kidney disease are limited.

Curcumin is the principal polyphenol in turmeric (Curcuma longa) and modulates NF-kB, Nrf2, and other inflammatory and oxidative pathways. Standard curcumin has very low oral bioavailability; supplements typically use piperine, phospholipid, or nanoparticle formulations. Meta-analyses suggest modest reductions in inflammatory markers, joint pain, and lipid measures, but effects vary by formulation and study quality. Evidence for direct longevity benefits in humans is limited.

Dietary fiber comprises non-digestible plant polysaccharides and oligosaccharides that resist hydrolysis by human intestinal enzymes. The two principal classes are soluble fiber (e.g., pectin, beta-glucan, inulin), which dissolves in water and forms a viscous gel, and insoluble fiber (e.g., cellulose, lignin), which adds stool bulk and accelerates colonic transit. In the colon, soluble fiber is fermented by resident microbes — including members of Bacteroidetes and Firmicutes — into short-chain fatty acids (SCFAs): acetate, propionate, and butyrate. Butyrate is the primary energy substrate for colonocytes and acts as a histone deacetylase inhibitor, dampening NF-κB-mediated inflammatory signalling; propionate travels to the liver to regulate gluconeogenesis; acetate circulates systemically and modulates appetite via GPR41 and GPR43. These mechanisms are directly relevant to aging: chronic low-grade systemic inflammation (inflamm-aging) is attenuated by higher SCFA production, and an age-related decline in SCFA-generating microbiota is well documented. Dose-response meta-analyses of prospective cohorts (Yao et al. 2023) show that each 10 g/day increment in fiber intake associates with roughly 10% lower all-cause mortality and 13% lower cardiovascular mortality; Reynolds et al. 2019 (Lancet) further established that intakes of 25–29 g/day confer the greatest reduction in non-communicable disease risk. These associations are observational, and randomised trial evidence on hard outcomes remains limited.

Dietary nitrate (NO₃⁻) is abundant in beetroot, leafy greens, and celery and is converted in the body to nitric oxide (NO) via a two-step cascade. Salivary glands concentrate circulating nitrate; bacteria on the tongue dorsum reduce it to nitrite (NO₂⁻), which is absorbed and further reduced to NO in blood and tissues — particularly under hypoxic conditions in working muscle and ischaemic endothelium. This entero-salivary pathway is distinct from the classical eNOS route and gains importance as eNOS activity declines with age (Lundberg, Weitzberg & Gladwin 2008). Kapil et al. (2015), randomised double-blind trial: 250 ml nitrate-rich beetroot juice daily for four weeks reduced systolic BP by ~8 mmHg and diastolic by ~4 mmHg in hypertensive adults, without significant adverse effects. Bailey et al. (2009): six days of beetroot juice supplementation cut the oxygen cost of moderate-intensity cycling by ~19% and extended time to exhaustion, attributed to more efficient mitochondrial respiration and lower ATP cost of contraction. The oral microbiome is mechanistically essential — antibacterial mouthwash that eliminates nitrate-reducing bacteria nearly abolishes plasma nitrite rise and haemodynamic effects, so antibiotic use and oral hygiene products directly modulate efficacy. Evidence in humans is strongest for acute BP lowering and exercise economy in non-elite populations; effects on all-cause mortality and longevity remain unproven in controlled trials.

EGCG is the most abundant catechin in green tea and a polyphenol with antioxidant, anti-inflammatory, and AMPK-modulating activity. Observational data link green tea consumption to lower cardiovascular and all-cause mortality. Trials of EGCG supplements show small effects on lipids, blood pressure, and body weight. High-dose extracts (typically above 800 mg EGCG/day) have been associated with liver enzyme elevations and hepatotoxicity; the European Food Safety Authority (EFSA) has identified this threshold as a safety concern and the EU has imposed limits on EGCG in food supplements. Direct evidence for human longevity from isolated EGCG remains limited.

Ergothioneine is a sulfur-containing histidine betaine, predominantly in its thione tautomeric form, synthesized exclusively by fungi, certain bacteria, and cyanobacteria; humans obtain it through diet, with mushrooms (porcini, oyster, shiitake) as the richest common sources. After ingestion it is actively transported into cells by OCTN1 (SLC22A4), expressed at high levels in metabolically demanding tissues including the brain, bone marrow, kidney, and muscle; ergothioneine is OCTN1's principal endogenous substrate. Unlike classical thiols, it does not auto-oxidize at physiological pH and does not catalyze hydroxyl-radical generation via the Fenton reaction, giving it selective cytoprotective properties against reactive oxygen and nitrogen species without pro-oxidant side-effects. Bruce Ames proposed ergothioneine as a putative "longevity vitamin" in 2018 under his triage theory, arguing that sub-optimal intake silently accelerates aging-related damage before frank deficiency appears. Plasma ergothioneine declines with age and in frailty. In the Malmö Diet and Cancer cohort (n = 3,236; median 21.4-year follow-up), ergothioneine was the metabolite most strongly associated with reduced cardiovascular mortality (HR ≈ 0.79 per SD) and all-cause mortality (HR ≈ 0.86 per SD) (Smith et al. 2020). A Singapore memory-clinic cohort (n = 470; average ~4-year follow-up) found that lower plasma levels predicted faster decline in memory, executive function, and processing speed (Wu et al. 2022). Randomized controlled trials in humans are limited and causality remains unestablished.

Fisetin is a flavonoid found in strawberries, apples, and persimmons. In aged mice, Yousefzadeh et al. (2018, EBioMedicine) reported reduced senescent cell burden and extended median lifespan using a late-life intermittent dosing protocol; the paper also documented reduced age-associated tissue dysfunction. The NIA Interventions Testing Program (Harrison et al., 2023, GeroScience) tested fisetin in genetically heterogeneous (UM-HET3) mice and did not replicate the lifespan extension in either sex; early human trials have likewise not yet demonstrated senescent-cell clearance, so the senolytic claim should be considered unconfirmed in rigorous models. Mechanisms include induction of apoptosis in senescent cells and modulation of inflammatory pathways, making it a candidate dietary senolytic under investigation. Human trials are ongoing, and clinical evidence in people remains preliminary.

Flavonoids are a large subclass of plant polyphenols with a 15-carbon benzo-γ-pyrone backbone, spanning six subfamilies: flavonols (quercetin, kaempferol; onions, kale), flavan-3-ols (catechins, epicatechins; tea, cocoa), anthocyanins (berries, red cabbage), flavanones (naringenin; citrus), flavones (luteolin, apigenin; herbs), and isoflavones (genistein; soy). Key mechanisms: scavenging reactive oxygen species, inhibiting NF-κB inflammatory signalling, activating Nrf2, and — for flavan-3-ols — raising nitric-oxide bioavailability to improve endothelial function. Observational evidence consistently links higher intake to lower cardiovascular and all-cause mortality: a dose-response meta-analysis of 39 cohorts (1.5 million individuals; Micek et al., 2021) found inverse associations with cardiovascular disease risk, strongest for anthocyanins and flavan-3-ols. A 2025 UK Biobank analysis (Parmenter, Cassidy et al.) found subclass diversity — not quantity alone — associated with 6–20% lower risk of all-cause mortality, CVD, type 2 diabetes, and neurodegenerative disease. RCT evidence is limited: COSMOS (Sesso, Manson et al., 2022) tested 500 mg/day cocoa flavanols in 21,442 older US adults; total cardiovascular events were not significantly reduced, but cardiovascular death fell 27%. COSMOS-Mind (Baker et al., 2022) found no cognitive benefit over three years. Bioavailability varies markedly by subclass and individual (partly gut-microbiome-dependent); isolated supplementation has not replicated benefits observed with whole-food dietary patterns.

The glycemic index (GI) ranks foods by how rapidly their digestible carbohydrates raise blood glucose relative to pure glucose (GI = 100). GI ≤ 55 is low, 56–69 moderate, ≥ 70 high. Because GI ignores serving size, glycemic load (GL) captures real-world impact: GL = GI × available carbohydrate (g) ÷ 100. High-GI and high-GL meals trigger rapid glucose spikes and reactive insulin surges, promoting hyperinsulinemia, oxidative stress, and low-grade inflammation — processes associated with insulin resistance, β-cell dysfunction, and accelerated biological aging. The PURE prospective cohort (Jenkins et al., NEJM 2021; 137,851 participants across five continents) found the highest versus lowest GL quintile carried a hazard ratio of 1.34 (95% CI 1.08–1.67) for major cardiovascular events in participants with pre-existing cardiovascular disease; no significant GL association was observed in the primary-prevention group. A Weizmann Institute study (Zeevi et al., Cell 2015; n = 800) demonstrated that postprandial glucose responses to identical foods vary substantially across individuals — driven by gut microbiome, genetics, and metabolic state — and that algorithm-based personalized advice outperformed GI-based recommendations in a randomized follow-up. The 2015 ICQC consensus affirms low-GI/GL diets as evidence-based strategies for preventing type 2 diabetes and coronary heart disease, noting that food processing, ripeness, and meal composition can shift a food's effective GI by 20–30 points.

Glycine is the smallest and simplest amino acid, non-essential under normal conditions but conditionally essential in aging, pregnancy, and disease states where demand may exceed endogenous synthesis from serine and threonine. It is the most abundant amino acid in collagen and a structural backbone of glutathione (as the third residue of the γ-Glu-Cys-Gly tripeptide), explaining its role as a rate-limiting substrate for glutathione synthesis in older adults whose glycine levels are typically low. Glycine also acts as an inhibitory neurotransmitter in the spinal cord and brainstem, modulates NMDA receptor activity, and participates in one-carbon metabolism, bile acid conjugation, and creatine synthesis. Dietary sources include gelatin, skin, bones, and connective tissue; modern lean-meat-focused diets provide relatively little. Animal studies show lifespan extension by glycine supplementation in mice (ITP, Miller 2019); evidence from C. elegans is indirect, arising mainly from methionine restriction and one-carbon metabolism studies rather than direct glycine trials. In humans, glycine deficiency in older adults is increasingly recognized, and small pilot trials (particularly in the context of GlyNAC, n≈8 each) suggest restoration of glutathione levels and improvements in multiple aging-related biomarkers.

GlyNAC is the combined oral supplementation of glycine and N-acetylcysteine (NAC), designed to replenish both precursors of the tripeptide glutathione (γ-Glu-Cys-Gly), which declines progressively with age. The combination addresses the limiting precursors simultaneously — cysteine (via NAC) and glycine — rather than the gamma-glutamylcysteine step, which is typically less rate-limiting in older adults. Pioneered by Rajagopal Sekhar and colleagues at Baylor College of Medicine, a series of randomized, double-blind pilot trials in older adults (GlyNAC trials, published 2021–2024, with n≈8–24 per arm) using 16–24 weeks of supplementation reported restoration of erythrocyte glutathione toward young-adult levels and signals across multiple aging-associated domains (mitochondrial fuel oxidation, oxidative stress, inflammation, endothelial dysfunction, insulin resistance, genomic damage, muscle strength, gait speed). Independent replication and longer outcome trials are lacking. Evidence remains limited to short-duration trials with small samples; longer-term RCTs with clinical outcome endpoints are lacking. GlyNAC is commercially available as a dietary supplement and has no approved indication.

Hydroxytyrosol is an ortho-diphenolic compound and the principal antioxidant phenol in olive oil and olive leaves; in the fruit and oil it is largely bound within the more complex oleuropein structure, which hydrolyses to hydroxytyrosol during processing and digestion. Based on a 2011 EFSA scientific opinion, EU Commission Regulation 432/2012 authorises the health claim that "olive oil polyphenols contribute to the protection of blood lipids from oxidative stress", on the condition that the food provides at least 5 mg of hydroxytyrosol and its derivatives (e.g. oleuropein complex and tyrosol) per 20 g of olive oil. Cardiovascular outcome evidence for an EVOO-rich Mediterranean diet comes mainly from the PREDIMED trial. EFSA has also confirmed hydroxytyrosol as a safe novel food.

Lutein and zeaxanthin are dihydroxy xanthophyll carotenoids that accumulate in the macula, where they form the macular pigment and filter blue light. Dark green leafy vegetables (kale, spinach), corn and egg yolk are the main dietary sources. In the AREDS2 randomised trial (4203 participants at risk of advanced age-related macular degeneration), adding 10 mg lutein plus 2 mg zeaxanthin to the original AREDS supplement did not reduce progression in the primary analysis, but a subgroup with the lowest dietary intake of lutein/zeaxanthin benefited. AREDS2 also showed that lutein/zeaxanthin is an appropriate substitute for beta-carotene, which raised lung-cancer incidence in former smokers. Evidence for cognitive benefits exists but is less robust.

Lycopene is an acyclic, lipophilic carotenoid that gives tomatoes, watermelon and pink grapefruit their red colour. Bioavailability is higher from heat-processed tomato products (sauce, paste) than from raw tomatoes and is enhanced by dietary fat. In the 2017 Rowles meta-analysis of 42 observational studies and 692,012 participants, higher dietary intake and higher circulating lycopene were associated with a modestly reduced risk of prostate cancer (~1% per 2 mg extra lycopene). Randomised supplementation trials have been smaller and inconclusive, so the protective association rests primarily on observational data and is most plausibly attributed to a tomato-rich dietary pattern rather than to isolated lycopene capsules. There is no EU-authorised health claim for lycopene.

The Mediterranean diet is an eating pattern emphasizing vegetables, fruits, legumes, whole grains, nuts, olive oil, and fish, with moderate dairy and limited red meat. Rich in monounsaturated fats, fiber, and polyphenols, it is associated with lower systemic inflammation, improved lipid profiles, and better endothelial function. Long-term adherence is associated in cohort studies with reduced type 2 diabetes risk and all-cause mortality. The PREDIMED trial (Mediterranean diet supplemented with extra-virgin olive oil or mixed nuts; retracted and republished in 2018) showed roughly a 30% reduction in a composite cardiovascular endpoint (myocardial infarction, stroke, cardiovascular death), but was not powered for and did not demonstrate an all-cause mortality benefit.

Methionine restriction (MR) is the dietary reduction of the sulphur amino acid methionine without overall caloric restriction. Orentreich and colleagues first reported in 1993 that a methionine-deficient diet extends maximal lifespan in rats; Miller et al. extended this to mice in 2005, showing a longer lifespan and slowed immune and lens ageing on a low-methionine diet. Proposed mechanisms include reduced one-carbon flux, lower hepatic IGF-1 and altered hydrogen-sulphide signalling. Plant-based protein sources (legumes, cereals) tend to be relatively low in methionine compared with animal protein (eggs, meat, dairy), so a partially plant-leaning diet shifts intake downwards. Human data are limited to short-term metabolic studies; MR is a mechanistic concept rather than a validated clinical intervention.

The MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) is a hybrid eating pattern targeting brain health. It emphasizes leafy greens, berries, nuts, whole grains, beans, fish, poultry, and olive oil while limiting red meat, butter, cheese, pastries, and fried food. Observational studies link higher adherence to slower cognitive decline and lower Alzheimer's incidence, though a 2023 randomized controlled trial (Barnes et al., NEJM) found no significant difference in cognition or brain-MRI outcomes between MIND and a mild calorie-restricted control diet over three years — both arms improved equally.

N-acetylcysteine is an acetylated form of the amino acid cysteine, used clinically as a mucolytic and as the standard antidote for paracetamol (acetaminophen) overdose. Its principal mechanism in both clinical and longevity contexts is replenishment of intracellular cysteine, the rate-limiting precursor for glutathione biosynthesis, thereby restoring the capacity of the γ-glutamyl-cysteinyl-glycine (GSH) system to buffer reactive oxygen species, support mitochondrial redox balance, and facilitate phase II detoxification. Oral bioavailability is moderate and variable due to first-pass metabolism; liposomal and sustained-release formulations are under study. Beyond antioxidant support, NAC modulates NF-κB-mediated inflammatory signaling and may attenuate cysteine-related DNA methylation shifts. As a standalone agent, it has been evaluated in chronic obstructive pulmonary disease, psychiatric disorders, and metabolic disease with mixed results. In the longevity context it is most relevant as the cysteine-donating half of the GlyNAC combination.

NMN is a nucleotide and NAD+ precursor in the salvage pathway, feeding into a coenzyme central to energy metabolism, sirtuin activity, and DNA repair. Oral NMN is absorbed and raises blood NAD+ in humans, but evidence for clinical longevity benefits remains limited. Trials report modest improvements on specific endpoints such as the 6-minute walk test, muscle insulin sensitivity, or grip strength; large, long-term outcome studies are lacking. NMN's US dietary supplement status was contested from 2022 to 2025, when the FDA reversed its earlier drug-exclusion ruling and confirmed that NMN may lawfully be marketed as a dietary supplement. On 13 May 2026 the European Food Safety Authority (EFSA) issued a positive scientific opinion on EffePharm's β-NMN (Uthever®) with a proposed safe upper intake of 300 mg/day for healthy adults (excluding pregnant and lactating women); European Commission authorisation as a Novel Food remains pending. Regulatory status in other regions varies.

NR is a vitamin B3 form and NAD+ precursor that is metabolized via salvage pathways to increase NAD+, with NMN as a possible intermediate. Human trials reliably show that oral NR raises blood NAD+ and/or related metabolites and is well tolerated. Evidence for downstream clinical benefits, such as improved physical performance, metabolic health, or healthspan, is mixed and largely confined to small, short-duration studies.

Eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) are long-chain polyunsaturated fatty acids found principally in fatty fish and fish oil (with algal supplements as the primary source for vegans). Their principal dietary precursor, alpha-linolenic acid (ALA), is found in flaxseed, chia, and walnuts, but conversion to EPA and DHA in humans is inefficient and highly variable. EPA and DHA are incorporated into cell membranes altering fluidity and lipid-raft composition, and serve as substrates for anti-inflammatory specialized pro-resolving mediators (SPMs) including resolvins and protectins, in contrast to the pro-inflammatory eicosanoids generated from omega-6 arachidonic acid. At pharmacological doses (≥2 g/day EPA+DHA), they reduce serum triglycerides by 20–50%; the REDUCE-IT trial showed that 4 g/day icosapent ethyl (a highly purified EPA ethyl ester) reduced major cardiovascular events in statin-treated hypertriglyceridemic patients, though the mineral oil placebo has been questioned. Observational data consistently associate higher oily-fish intake and blood omega-3 index with lower all-cause and cardiovascular mortality; supplementation trials in generally healthy populations show more modest and inconsistent benefits.

Polyphenols are a structurally diverse class of plant secondary metabolites — numbering over 8,000 known compounds — defined by one or more aromatic rings bearing hydroxyl groups. Major subclasses include flavonoids (quercetin, catechins, anthocyanins), stilbenes (resveratrol), phenolic acids, and lignans. At physiological concentrations, polyphenols act less as direct antioxidants than as hormetic stressors and xenohormetic signals: they activate Nrf2, AMPK, and SIRT1, inducing mitochondrial biogenesis, autophagy, and anti-inflammatory gene programs. At least 62 polyphenols have extended lifespan or improved aging biomarkers in model organisms. In humans, a 2024 meta-analysis of seven cohort studies (178,657 participants) associated higher polyphenol intake with a 7% reduction in all-cause mortality risk, and a 2024 systematic review of RCTs (Mekhora, Lamport & Spencer) found supplementation significantly improved verbal memory and executive function while reducing interleukin-6, though effect sizes were modest. A central limitation is bioavailability: most polyphenols are poorly absorbed, undergo extensive first-pass metabolism, and reach systemic circulation at low micromolar concentrations; gut-microbiota composition critically shapes conversion of glycosides into bioactive aglycones and urolithins. Causal evidence for lifespan extension in humans is absent; current data support polyphenol-rich dietary patterns rather than isolated high-dose supplements.

Pterostilbene is a dimethylated stilbene analogue of resveratrol naturally present in blueberries, grapes, and Pterocarpus marsupium heartwood. The two methoxy groups replacing the hydroxyl groups of resveratrol substantially increase lipophilicity and metabolic stability, conferring approximately two- to fourfold higher oral bioavailability and a longer half-life compared with resveratrol. Like resveratrol, it is studied as a putative SIRT1 activator and AMPK modulator, and additionally activates PPARα, relevant to fat oxidation. In rodent models it improves cognitive function, reduces inflammatory and oxidative markers, and extends lifespan in some strains. Human clinical data are limited to small trials examining lipid profiles, blood pressure, and antioxidant markers, with modest and inconsistent effects; a randomized human trial (Riche et al. 2014, NCT01267227) reported LDL elevation at higher pterostilbene doses in the monotherapy arm — a finding notable enough that ChromaDex subsequently ceased new pterostilbene ingredient orders. No robust evidence supports anti-aging benefit in humans, and long-term safety data are sparse.

Quercetin is a flavonoid abundant in onions, apples, capers, and berries with antioxidant and anti-inflammatory activity. It is investigated as a senolytic, though standalone activity is inconsistent in human cell models; the combination with dasatinib (D+Q) is the regimen actually studied in early human senolytic trials. Standalone supplementation has shown small, inconsistent blood pressure effects mainly in hypertensive populations, and bioavailability is low. Human anti-aging evidence is preliminary.

Resveratrol is a stilbene polyphenol found in grape skins, red wine, and Japanese knotweed. It is studied as a putative sirtuin (SIRT1) activator and AMPK modulator, with effects on inflammation and mitochondrial function in preclinical models. Human trials have produced inconsistent results, and oral bioavailability is poor. There is currently no robust evidence that resveratrol supplementation extends human lifespan or healthspan.

Selenium is incorporated into proteins as the amino acid selenocysteine (the 21st amino acid), forming a class of enzymes called selenoproteins — 25 encoded in the human genome. Key members include the glutathione peroxidases (GPx1-GPx4), which neutralise reactive oxygen species, and the thioredoxin reductases (TxnRD1-3); three iodothyronine deiodinases (DIO1-3) regulate T4-to-T3 thyroid hormone conversion. The functional marker of adequacy is saturation of selenoprotein P (SELENOP) at plasma concentrations around 110 µg/L — the threshold used in the Nordic Nutrition Recommendations 2023 to define optimal intake (75-90 µg/day). A U-shaped dose-response is evident: deficiency (serum selenium below 90 µg/L) associates with accelerated epigenetic aging on DunedinPACE and GrimAge clocks in the Berlin Aging Study II (Vetter et al. 2025, n=1,568); excess carries independent risk — a case-control study (Le et al. 2024) identified a safe window of 111-124 µg/day with elevated cancer risk at both extremes. The SELECT trial (Klein et al. 2011, n=35,533) tested 200 µg/day L-selenomethionine in men with replete selenium; neither selenium nor vitamin E reduced prostate cancer incidence, showing supplementation in nutrient-replete populations does not extrapolate from deficiency-correction data.

Soy isoflavones are polyphenolic phytoestrogens — plant-derived compounds structurally similar to 17β-estradiol — concentrated in soybeans and soy-derived foods, with genistein and daidzein as the two principal aglycones (bioactive forms after gut deglycosylation). Both bind preferentially to estrogen receptor beta (ERβ) with 100- to 1000-fold lower affinity than endogenous estrogen, producing tissue-selective partial agonist/antagonist effects. A relevant variable is equol production: approximately 20–30% of Western adults and 50–60% of Asian adults harbour bacteria (primarily Adlercreutzia equolifaciens and Slackia isoflavoniconvertens) that convert daidzein to S-equol, a metabolite with higher ERβ affinity, explaining much individual response variability. RCTs and meta-analyses support a significant reduction in hot-flash frequency (Luan 2025) and small LDL-cholesterol lowering (~5 mg/dL across 11 RCTs, Taku 2007); equol producers show greater benefit. A 2022 meta-analysis (Boutas et al., 18 studies) found no elevated breast cancer risk and a trend toward reduced recurrence, consistent with ERβ anti-proliferative signalling in mammary tissue — mechanistically distinct from ERα-driven tumour promotion by pharmaceutical oestrogens.

Spermidine is a naturally occurring polyamine found in wheat germ, aged cheese, soy, and mushrooms, though content varies widely by source and processing. It induces autophagy, the cellular recycling process implicated in aging, and extends lifespan in yeast, worms, flies, and mice. In humans, dietary intake correlates with lower mortality in observational data; limited preliminary trials have explored possible cognitive signals, but results are not definitive. Causal effects on human longevity are not yet established.

Sulforaphane is an isothiocyanate generated when broccoli, broccoli sprouts, and other cruciferous vegetables are chewed or chopped. It activates the Nrf2 pathway, upregulating antioxidant and phase II detoxification enzymes. Human studies report effects on biomarkers of oxidative stress, inflammation, and cardiometabolic risk, with promising but mixed signals in autism and cancer chemoprevention. Long-term clinical outcomes from sulforaphane supplementation are not yet established.

Taurine is a sulfur-containing non-proteinogenic amino acid synthesized in humans from cysteine via the cysteine sulfinic acid pathway, with dietary intake from animal foods — particularly shellfish, dark poultry meat, and fish — contributing substantially to circulating levels. It is highly concentrated in heart, skeletal muscle, retina, and neurons, where it acts as an osmolyte, modulates intracellular calcium handling, stabilizes mitochondrial membrane potential, and attenuates oxidative and endoplasmic-reticulum stress. A landmark 2023 paper by Singh et al. in Science reported that taurine levels in blood decline markedly with age in mice, monkeys, and humans, and that supplementing physiological amounts of taurine extended median lifespan in both male and female C57BL/6J mice (by approximately 10–12%) and improved several health metrics in middle-aged monkeys; mechanistic studies implicated suppression of cellular senescence, inflammation, DNA damage, and mitochondrial dysfunction. In humans, taurine association with longevity is observational only, and no interventional evidence for lifespan extension exists. A 2025 NIH-led re-analysis (Marcangeli et al., Aging Cell 2025; companion work by Fernandez et al., Science 2025) found that circulating taurine often increases or remains stable with age in humans, monkeys, and mice, directly challenging the central age-related decline narrative of Singh 2023. Taurine is present in energy drinks and is sold as a supplement; at the doses commonly studied it has not raised acute safety signals in adults, but long-term high-dose data in humans are limited.

Vitamin E is a family of eight fat-soluble molecules — four tocopherols (α, β, γ, δ) and four tocotrienols (α, β, γ, δ) — sharing a chromanol ring but differing in their tail: tocopherols carry a saturated phytyl chain, tocotrienols an unsaturated isoprenoid chain with greater membrane mobility. The liver retains α-tocopherol via α-TTP, making it the dominant circulating form and reference standard. Its principal role is chain-breaking antioxidation: α-tocopherol donates a hydrogen atom to lipid peroxyl radicals, halting oxidative chain reactions and protecting membrane polyunsaturated fatty acids. Vitamers also suppress the NF-κB pathway, modulate Nrf2, and influence gene expression in cholesterol synthesis and apoptosis. Dietary sources — wheat-germ oil, sunflower seeds, almonds, avocado — are linked in observational data with lower mortality; a 30-year ATBC cohort analysis found serum α-tocopherol inversely associated with all-cause mortality. High-dose supplementation differs: Miller et al. (2005; 19 RCTs, >135,000 participants) found a dose-dependent mortality increase above ~150 IU/day. The SELECT trial (Klein et al., 2011; ~35,000 men) found α-tocopherol raised prostate cancer incidence 17% versus placebo (HR 1.17; 99% CI 1.004–1.36). Tocotrienols — γ and δ forms in particular — are under investigation for neuroprotective and anti-senescence effects, but human trial data remain limited; co-administered α-tocopherol may suppress their bioavailability. Evidence supports meeting vitamin E needs through food over high-dose supplements.

Menaquinone-7 is a long-chain form of vitamin K2 in which the side chain has seven isoprene units, giving it a longer half-life than vitamin K1 (phylloquinone) or MK-4. Like other vitamin K vitamers, it serves as a cofactor for the gamma-carboxylation of Gla proteins, including osteocalcin (bone) and matrix Gla protein (vascular wall). Dietary sources are limited: natto (a Bacillus subtilis-fermented soy food) is by far the richest, with smaller amounts in cheese and fermented dairy. In a 3-year RCT in 244 postmenopausal women, 180 microgram MK-7 daily slowed loss of vertebral height and bone mineral density. The EU has authorised vitamin K claims for normal blood coagulation and maintenance of normal bones; cardiovascular outcome evidence remains inconsistent.