The supplement library.

A highly bioavailable chelated form of magnesium that crosses the blood-brain barrier to activate GABA receptors and reduce cortisol. Multiple RCTs show improvements in sleep efficiency and subjective sleep quality at 300–400mg. The bisglycinate form produces significantly fewer GI side effects than oxide or citrate.

Uniquely able to elevate magnesium concentrations specifically in the brain, where other forms cannot reach in meaningful quantities. Animal and human trials show improvements in short and long-term memory and synaptic density. Used when cognitive performance data alongside HRV signals concurrent mental fatigue.

An amino acid found in green tea that promotes alpha-wave activity in the brain — a state of calm focus, without sedation. At 100–400mg it consistently reduces time-to-sleep-onset and improves sleep architecture. Synergistic with caffeine at 2:1 ratio for focus during the day; alone it primes evening wind-down.

The primary circadian hormone produced by the pineal gland in response to darkness. At low doses (0.5–1mg), it advances sleep timing without disrupting natural sleep architecture. Most effective taken 30–60 minutes before target sleep time. Recommended when HRV data indicates circadian rhythm disruption rather than sleep depth issues.

An inhibitory amino acid that lowers core body temperature by promoting peripheral vasodilation — one of the body's key triggers for sleep onset. 3g before bed has been shown in controlled trials to improve subjective sleep quality and next-day cognitive performance. Also a structural component of collagen and glutathione.

Contains both melatonin and procyanidins that inhibit COX-2 and other inflammatory enzymes. Randomised trials show it increases total sleep time by ~85 minutes and reduces insomnia severity index scores. Simultaneously accelerates muscle damage repair after eccentric exercise — a dual-action recovery agent.

One of the most studied adaptogenic plants. Withanolides and withaferin-A modulate the hypothalamic-pituitary-adrenal (HPA) axis, reducing cortisol output under load. Multiple double-blind trials at 300–600mg/day show significant reductions in perceived stress, anxiety, and morning cortisol within 8 weeks.

An adaptogen that works by inhibiting catechol-O-methyltransferase (COMT), slowing the breakdown of dopamine, norepinephrine, and serotonin under stress. Consistently demonstrated in trials to reduce mental fatigue and burnout while maintaining cognitive performance during high-demand periods. Particularly effective at 200–400mg in the morning.

Bacosides A and B enhance synaptic communication in the hippocampus and prefrontal cortex by increasing kinase activity and receptor density. Meta-analyses of RCTs consistently show improvements in logical memory and information processing speed after 8–12 weeks. Has anxiolytic properties — it does not stimulate.

A phospholipid critical for neuronal membrane integrity and neurotransmitter vesicle release. Shown at 300–800mg/day to blunt the cortisol response to acute physical and psychological stress. Studied extensively in athletes: reduces overtraining markers and supports attention and working memory under fatigue.

A direct precursor to serotonin that crosses the blood-brain barrier more efficiently than tryptophan. Supplementation at 50–300mg raises central serotonin levels, supporting mood stability, reducing sleep onset, and moderating appetite. Most relevant when stress indices are chronically elevated without adequate recovery.

Coenzyme Q10 is an electron carrier in the mitochondrial respiratory chain — essential for ATP synthesis. Endogenous levels decline with age and are significantly depleted by statin medications. Supplementation (100–300mg as ubiquinol) improves mitochondrial density, exercise capacity, and cardiac output. Most impactful when fatigue persists despite adequate sleep.

The eight B vitamins function as essential coenzymes across cellular energy metabolism (B1, B2, B3), DNA synthesis (B9, B12), and neurotransmitter production (B6). A deficiency in any single B vitamin creates a rate-limiting bottleneck. A complete complex ensures the entire metabolic pathway operates without restriction.

Essential for myelin sheath synthesis, red blood cell formation, and homocysteine metabolism. Deficiency develops silently over months-to-years, producing fatigue, cognitive decline, and peripheral neuropathy. Plant-based and low-meat diets reliably deplete B12 — supplementation with methylcobalamin is the most bioavailable form.

Iron deficiency is the most common nutritional cause of fatigue and exercise intolerance globally. The bisglycinate chelate form provides 3× the absorption rate of ferrous sulfate with a fraction of the gastrointestinal side effects. Recommended when resting heart rate trends upward with declining HRV — a signal pattern consistent with suboptimal iron status.

Transports long-chain fatty acids across the inner mitochondrial membrane for beta-oxidation, directly supporting ATP production. Unlike plain L-Carnitine, the acetyl form crosses the blood-brain barrier, providing parallel cognitive and neuroprotective benefits. Most effective at 500–2000mg in the morning before physical or cognitive effort.

A steroid hormone that acts on over 200 gene targets regulating innate and adaptive immunity, muscle contractility, calcium absorption, and mood. The majority of UK adults are deficient from October to March. Recommended year-round at 1000–4000 IU, combined with vitamin K2 to direct calcium into bone rather than soft tissue.

Works synergistically with Vitamin D3, activating osteocalcin and matrix GLA-protein to direct calcium into bone mineral and away from arterial walls. MK-7 (menaquinone-7) has a biological half-life of ~3 days — the most studied K2 form for long-term bone density and cardiovascular risk reduction. Recommended alongside any D3 protocol.

EPA and DHA are structural fats in neuronal and cardiac cell membranes that modulate inflammatory signalling through prostaglandin and resolvin pathways. High-EPA formulations (>60% EPA by weight) are most effective for mood stability and HRV improvement. Consistently associated with reduced cardiovascular risk at 2–4g daily.

A water-soluble antioxidant and essential cofactor for collagen synthesis, carnitine production, and norepinephrine biosynthesis. Meta-analyses show that regular supplementation (≥200mg/day) halves the incidence of colds in athletes under high physical load. Liposomal formulations achieve 2–4× higher plasma concentrations than standard ascorbic acid.

Required as a cofactor for over 300 enzymatic reactions, including those governing immune response, testosterone synthesis, DNA repair, and wound healing. Picolinate chelation significantly increases intestinal absorption. Athletes are particularly at risk of deficiency through sweat losses — zinc is concentrated in perspiration at rates that readily exceed dietary intake.

A direct precursor to glutathione — the body's master intracellular antioxidant. Supplementation reliably raises glutathione levels in muscle and liver tissue, reducing exercise-induced oxidative damage and supporting detoxification. Also demonstrated to reduce mucus viscosity and support respiratory health, with emerging evidence in OCD and compulsive behaviours.

The primary bioactive in turmeric, curcumin potently inhibits the NF-κB transcription factor and COX-2 enzyme — two of the central regulators of the inflammatory cascade. Bioavailability is near-zero without enhancement; formulations with piperine (black pepper) or phospholipid complexes increase absorption 20–2000×. Most relevant when stress and recovery markers are persistently elevated.

Hydrolysed collagen provides glycine, proline, and hydroxyproline — the building blocks that stimulate fibroblasts to synthesise new collagen in tendons, ligaments, and cartilage. A controlled trial found that 10g of collagen peptides taken with 50mg of vitamin C one hour before exercise led to a 2× increase in collagen synthesis markers.

Anthocyanins in elderberry (Sambucus nigra) bind to and inhibit influenza virus surface proteins, preventing cellular entry, while also modulating cytokine production to amplify the immune response. Meta-analyses show a significant reduction in the duration and severity of cold and influenza symptoms, with the largest effects when taken at onset.

The primary intracellular electrolyte, critical for membrane potential, muscle contraction, and nerve impulse transmission. Blood pressure regulation is tightly linked to the sodium:potassium ratio — most people consume significantly less than the 3500mg daily recommendation. Endurance athletes routinely deplete potassium through sweat and must replenish actively.

The primary extracellular electrolyte governing plasma volume, nerve transmission, and fluid balance. Endurance athletes are at specific risk of exercise-associated hyponatraemia from over-hydration with low-sodium fluids. Targeted sodium supplementation during prolonged activity maintains plasma osmolality, preventing performance drops and reducing cramping.