The Supplement Library

Physiological role: EPA and DHA are structural components of cell membranes — particularly concentrated in the brain, retina, and heart. EPA serves as a precursor to anti-inflammatory eicosanoids. DHA is essential for neuronal membrane fluidity and synaptic function.

Research: The NIH Omega-3 Fact Sheet provides a comprehensive review. The British Heart Foundation recommends 2 fish portions weekly (1 oily). EFSA has authorised health claims for EPA+DHA at 250mg/day.

Food sources: Salmon (~2.2g/100g), mackerel (~2.6g/100g), sardines (~1.5g/100g), herring, anchovies, trout. Plant ALA from flaxseed/chia (conversion to EPA/DHA <10%).

Supplements: Fish oil capsules typically provide 300-1,000mg combined EPA+DHA. NHS notes most can get enough from diet alone. Algae-based options available.

Safety: May interact with blood-thinners. >3g/day only under medical supervision. NIH safety info.

Physiological role: Functions as a hormone precursor. Active form (calcitriol) regulates calcium/phosphorus absorption, bone mineralisation, and immune cell function. Vitamin D receptors (VDRs) exist in prostate tissue, suggesting a role in normal prostate cell physiology.

Research: NIH Vitamin D Fact Sheet. The NHS recommends 10mcg (400 IU) during autumn/winter for everyone. For people with darker skin — including African and Caribbean heritage — supplementation may be advisable year-round, as melanin reduces UV-driven synthesis. See Public Health England SACN report.

Food sources: Oily fish, egg yolks, fortified foods, UV-exposed mushrooms.

Supplements: D3 (cholecalciferol) preferred over D2. RDA: 400 IU (UK), 600-800 IU (US). Test levels first (25-hydroxyvitamin D blood test).

Safety: Excess (>4,000 IU/day long-term unsupervised) can cause hypercalcaemia. Get tested first. NHS guidance.

Physiological role: Cofactor for 300+ enzymatic reactions. Involved in immune function, protein synthesis, wound healing, DNA synthesis. The prostate accumulates zinc at 10-15× higher concentrations than most tissues. Some studies find lower zinc in abnormal vs healthy prostate tissue.

Research: NIH Zinc Fact Sheet. RDA for men: 11mg (US) / 9.5mg (UK).

Food sources: Pumpkin seeds (2.5mg/30g), oysters (~74mg/serving — richest source), crab, chickpeas, lentils, cashews.

Supplements: Zinc picolinate/citrate absorb better than zinc oxide. Take with food.

Safety: Upper limit 40mg/day. Excess impairs copper absorption. NIH safety.

Physiological role: One of the most potent singlet oxygen quenchers among carotenoids (~2× more effective than beta-carotene). Accumulates in prostate, adrenal glands, and liver.

Research: A 2015 meta-analysis (26 studies, Medicine) found higher intake associated with reduced prostate risk. WCRF includes lycopene in continuous updates. Linus Pauling Institute review.

Food sources (best cooked with fat): Tomato paste (~30mg/100g — highest bioavailable source), cooked tomatoes, watermelon, pink grapefruit, guava.

Safety: Generally well-tolerated. Very high intake may cause harmless skin discolouration.

Physiological role: Contains hericenones (fruiting body) and erinacines (mycelium) — shown in lab/animal studies to stimulate nerve growth factor (NGF) production. NGF is essential for neuron growth, maintenance, and survival.

Research: A 2009 double-blind RCT (Phytotherapy Research) showed improved cognitive scores in older adults after 16 weeks. NCCIH notes research is still early-stage. Latest studies: PubMed: Hericium erinaceus.

Forms: Capsules (standardised to 30%+ beta-glucans), tinctures, powder, or whole mushroom (seafood-like flavour). Typical dose: 500-3,000mg/day dried extract.

Safety: Generally well-tolerated. Avoid with mushroom allergy. May interact with immunosuppressants.

Physiological role: EGCG scavenges reactive oxygen species, chelates metal ions, and modulates PI3K/Akt, MAPK, and NF-κB pathways — involved in cell growth, inflammation, and apoptosis. 25-100× more potent than vitamins C/E in lab settings.

Research: 17,000+ studies on PubMed. NCCIH green tea overview. Japanese epidemiological studies show associations between regular intake and various health markers.

Best source: Brewed green tea (2-3 cups/day = ~200-300mg catechins). Brew at 70-80°C for 2-3 min. Matcha provides higher concentrations.

Safety: Brewed tea is safe. Concentrated supplements (>800mg/day catechins) linked to rare liver concerns — EFSA recommends staying below 800mg/day. Take with food. NCCIH safety.

Physiological role: Incorporated into 25+ selenoproteins (glutathione peroxidases, thioredoxin reductases) that neutralise oxidative damage. Also involved in thyroid function and immune support.

Research: NIH Selenium Fact Sheet. The SELECT trial found supplementation alone did not reduce prostate risk and may have increased diabetes risk — underscoring that both deficiency AND excess are harmful. Optimal status from diet is best.

Food sources: Brazil nuts (~68-91mcg per nut — RDA is 55-75mcg). Also: tuna, sardines, shrimp, eggs, sunflower seeds. BNF advises against supplements unless deficiency confirmed.

Safety: Upper limit 400mcg/day. Do not exceed 3-4 Brazil nuts/day. Excess causes hair loss, nail brittleness, neurological symptoms. NIH safety.

Physiological role: Accumulate in the macula as natural blue-light filters with localised antioxidant protection. AREDS2 (National Eye Institute) found 10mg/2mg lutein/zeaxanthin supplementation beneficial. Broader roles under review: Linus Pauling Institute.

Food sources: Kale (~26mg/cup cooked — highest), spinach, collard greens, egg yolks, sweetcorn, orange peppers.

Safety: Generally well-tolerated. No upper limit established.

Key compounds: Curcumin (turmeric — NF-κB modulation), gingerol (ginger — anti-inflammatory), anthocyanins (hibiscus — antioxidant, blood pressure), apigenin (chamomile — GABA-binding, sleep-promoting).

Research: NCCIH: turmeric | chamomile. 2015 Cochrane review found hibiscus modestly reduces systolic blood pressure.

Recommended daily: Morning: green tea. Midday: turmeric-ginger. Afternoon: hibiscus/sorrel. Evening: peppermint. Bedtime: chamomile.

Safety: May interact with medications (turmeric with blood-thinners, hibiscus with BP meds, chamomile with sedatives). Consult your provider.