5-HTP
5-HTP is a serotonin precursor sold for mood, sleep and appetite. Evidence is limited, and combining it with antidepressants can be dangerous.
Amino acids & derivatives
Acetyl-L-carnitine (ALCAR)
An acetylated carnitine that crosses into the brain more easily. Studied for nerve and cognitive health; evidence is mixed and often in specific groups.
Amino acids & derivatives
Alpha-GPC
Alpha-GPC is a choline compound sold for focus and power output. The evidence is modest, and recent research has raised questions about long-term heart and stroke risk.
Brain & cognition
Alpha-lipoic acid
Alpha-lipoic acid is an antioxidant made by the body. It has some evidence for diabetic nerve symptoms, but it can lower blood sugar and affect medicines.
Longevity & mitochondrial
Apigenin
Apigenin is a plant compound from chamomile, popular as a bedtime add-on. Human evidence for sleep is thin, and most of the claims come from lab and animal studies.
Sleep, stress & mood
Ashwagandha
An Ayurvedic root extract taken for stress and sleep. Some decent short trials, but rare liver injury reports and thyroid effects mean it is not risk-free.
Herbs & adaptogens
Astaxanthin
Astaxanthin is a red antioxidant pigment from algae. It is popular for skin and eye health, but human trials are small and benefits modest.
Longevity & mitochondrial
B-complex
A B-complex bundles the eight B vitamins in one capsule. It can cover gaps in a poor diet, but it is not an energy booster for well-fed people.
Vitamins
Bacopa monnieri
Bacopa is an Ayurvedic herb sold for memory and focus. Small trials suggest a modest memory effect after about 12 weeks, but not an instant boost.
Brain & cognition
BCAAs (leucine, isoleucine, valine)
Three essential amino acids sold for muscle and recovery. If you already eat enough protein, they add little.
Protein & performance
Beetroot juice / dietary nitrate
Beetroot juice is a nitrate-rich drink that may slightly improve endurance and lower blood pressure for some people. Effects are modest and uneven.
Protein & performance
Berberine
A plant alkaloid with real but modest blood-sugar effects in studies. It interacts with many medicines and should be avoided in pregnancy.
Herbs & adaptogens
Beta-alanine
The pre-workout ingredient that makes your skin tingle. Modest evidence for high-intensity efforts lasting about one to four minutes.
Protein & performance
Betaine (trimethylglycine, TMG)
A compound found in beets and wheat that donates methyl groups. Used for homocysteine and, in sport, for power; evidence for performance gains is mixed.
Amino acids & derivatives
Biotin (vitamin B7)
Biotin is sold for hair and nails, but it helps mainly if you are deficient. High doses can also seriously distort blood tests, including heart and thyroid tests.
Vitamins
Boron
A trace element found in fruit, nuts and veg. Popular for bones, joints and testosterone claims, but human evidence is thin and not well established as essential.
Minerals
Caffeine
The most widely used stimulant. Reliably boosts alertness and endurance; pure powder is dangerous because a teaspoon can be a lethal dose.
Protein & performance
Calcium
The main mineral in bones and teeth. Food is the best source; supplements help only if intake is low, and high doses carry some risks.
Minerals
Chromium (picolinate)
A trace mineral sold for blood sugar and cravings. Evidence for any real effect is weak, and a true dietary need has never been firmly shown.
Minerals
Cinnamon
A common spice sold for blood sugar. Evidence is mixed and small; cassia cinnamon contains coumarin, which can harm the liver in excess.
Herbs & adaptogens
Citicoline (CDP-choline)
Citicoline is a natural compound sold for attention and memory. Evidence is mixed but a bit more consistent than for most brain supplements, mainly at 250 to 500 mg.
Brain & cognition
Collagen peptides
Broken-down collagen protein sold for skin, joints and tendons. Some trials show small benefits, though many are industry-funded and effects are modest.
Protein & performance
CoQ10
CoQ10 is a compound your cells make for energy production. Supplements are popular with statin users and for heart health, but the evidence is mixed.
Longevity & mitochondrial
Cordyceps
A medicinal fungus marketed for stamina and energy. Evidence in humans is limited and mixed, and the product you buy is usually not the wild fungus.
Herbs & adaptogens
Creatine monohydrate
The most researched sports supplement there is. Reliably helps short, high-intensity effort and lean mass gain alongside training.
Protein & performance
D-mannose
D-mannose is a simple sugar sold for urinary tract infections. Trial results are mixed, and it is not a substitute for antibiotics when you have an active infection.
Gut & digestion
DHEA
A steroid hormone made by the adrenal glands and sold in some countries as a supplement. It is a hormone, banned in sport, and its legal status varies by country.
Hormonal & sexual health
Digestive enzymes
Enzyme capsules taken with meals. Clearly useful for specific problems like lactose intolerance or pancreatic insufficiency, but little evidence for general use.
Gut & digestion
DIM
A compound formed from broccoli-family vegetables, sold for oestrogen balance. Human evidence is thin, and the claims on bodybuilding and hormone sites outrun it.
Hormonal & sexual health
Echinacea
A popular cold remedy from coneflower. Evidence is mixed, with at best a small effect on cold duration or risk.
Herbs & adaptogens
Elderberry
Popular cold and flu remedy made from European elder berries. Some small trials show promise; raw berries are toxic and need to be cooked.
Herbs & adaptogens
Electrolytes
Salts that help your body hold water. Oral rehydration salts are well proven for diarrhoea and vomiting; most trendy daily mixes are unnecessary for casual users.
Minerals
Essential amino acids (EAAs)
All nine essential amino acids in free form. A more logical alternative to BCAAs, though whole protein still does the job for most.
Protein & performance
Fenugreek
A spice and herb used for libido, blood sugar and milk supply. Evidence is limited and mixed, and it has notable drug interactions and side effects.
Hormonal & sexual health
Fisetin
Fisetin is a plant flavonol hyped as a senolytic that clears ageing cells. The strongest results are in mice and cells; human evidence is early and unproven.
Longevity & mitochondrial
Folate (folic acid)
Folate (B9) is essential for cell growth. Folic acid is advised before and during early pregnancy; outside of that, extra is rarely needed.
Vitamins
GABA (oral)
GABA is the brain's main calming messenger, but it is unclear whether swallowing it gets into the brain. Evidence for calm and sleep is thin.
Sleep, stress & mood
Ginkgo biloba
Extract of ginkgo tree leaves sold for memory and circulation. Disappointing evidence for memory, and a real bleeding-risk caution.
Herbs & adaptogens
Glucosamine and chondroitin
Cartilage-building blocks sold for joint pain. Evidence for knee osteoarthritis is mixed, with small average benefits and some people noticing more than others.
Joints & connective tissue
Glycine
The smallest amino acid. Taken in the evening for sleep quality, with small studies behind it, and as a collagen building block.
Amino acids & derivatives
Green tea extract
Concentrated green tea catechins (EGCG). Small effects on weight at best, and high-dose extracts have been linked to liver injury.
Herbs & adaptogens
HMB (beta-hydroxy beta-methylbutyrate)
A leucine metabolite sold to reduce muscle breakdown. Useful in untrained or older people, with little extra benefit for experienced lifters.
Protein & performance
Holy basil (tulsi)
An Ayurvedic herb and tea used for stress and wellbeing. Early trials are encouraging but small, and it may affect blood sugar and fertility.
Herbs & adaptogens
Huperzine A
Huperzine A is a plant-derived cholinesterase inhibitor sold for memory. It acts like a drug, has real interaction risks, and is not a casual supplement.
Brain & cognition
Hyaluronic acid (oral)
A natural molecule in skin and joints. Oral supplements have some small-trial support for knee pain and skin dryness, but evidence is limited.
Joints & connective tissue
Inositol (myo-inositol)
Inositol is a sugar-like compound studied for PCOS and mood. Evidence is best for metabolic and ovulation outcomes in PCOS, and weaker for anxiety and depression.
Sleep, stress & mood
Iodine (kelp, potassium iodide)
Needed to make thyroid hormones. Many UK adults, especially those avoiding fish and dairy, get little, but both too little and too much can upset the thyroid.
Minerals
Iron (ferrous forms)
Essential for carrying oxygen in blood. Works well when you are genuinely deficient, but taking it unnecessarily can harm, and overdose is dangerous for children.
Minerals
L-arginine
Amino acid the body uses to make nitric oxide. Widely sold for pumps and blood flow, but oral evidence is weaker than the marketing.
Amino acids & derivatives
L-carnitine L-tartrate
An oral, fast-absorbing carnitine used in sport for recovery. Evidence for fat loss is weak; recovery benefits are small but more plausible.
Amino acids & derivatives
L-citrulline / citrulline malate
A non-essential amino acid popular in pre-workouts for pumps and endurance. Evidence is mixed but leans slightly positive at proper doses.
Amino acids & derivatives
L-glutamine
The most abundant amino acid in the body. Popular for gut and recovery, but evidence in healthy people is thin.
Amino acids & derivatives
L-theanine
An amino acid from tea leaves taken for calm focus. Evidence for mild effects on relaxation and attention, especially alongside caffeine, is modest.
Amino acids & derivatives
L-tyrosine
An amino acid your body uses to make dopamine and noradrenaline. May help mental performance under acute stress; evidence in everyday use is weak.
Amino acids & derivatives
Lion's mane mushroom
Lion's mane is a shaggy edible mushroom sold for focus and nerve health. The hype runs well ahead of the human evidence, which is small and early.
Brain & cognition
Lutein and zeaxanthin
Lutein and zeaxanthin are carotenoids concentrated in the retina. They may help in a specific eye condition (AREDS2 context) but are not proven to improve normal vision.
Brain & cognition
Maca root
A Peruvian root vegetable sold for libido and energy. It is food-like and generally mild, but the evidence is small and does not show hormone changes.
Hormonal & sexual health
Magnesium
An essential mineral involved in hundreds of body processes. Helpful if you are short; evidence for sleep, mood and cramp benefits is mixed and modest.
Minerals
Melatonin (oral supplement)
Oral melatonin helps shift body-clock timing more than it knocks you out. It is prescription-only in the UK but sold as a supplement in many other countries.
Sleep, stress & mood
Milk thistle
A herbal extract popular as a liver supplement. Generally well tolerated, but good evidence for liver benefit is thin.
Herbs & adaptogens
MSM
A sulphur compound sold for joint pain and recovery. Small trials show modest benefits for knee pain, but the evidence is thin and the products are variable.
Joints & connective tissue
Multivitamin
A multivitamin is cheap insurance against a patchy diet, not a shortcut to better health. Large trials show little effect on major disease in well-fed adults.
Vitamins
NAC (N-acetylcysteine)
A form of the amino acid cysteine that supports glutathione production. A real medicine in hospitals; evidence for supplement uses is mixed.
Amino acids & derivatives
Nicotinamide riboside (NR)
Nicotinamide riboside is a form of vitamin B3 that raises NAD+ levels. It is better studied than most longevity products, but real-world benefits remain unproven.
Longevity & mitochondrial
NMN (nicotinamide mononucleotide)
NMN is a precursor to NAD+ sold for healthy ageing. It raises NAD+ in humans, but proof of real-world benefits is thin and its legal status is unsettled.
Longevity & mitochondrial
Omega-3 fish oil
Long-chain omega-3s EPA and DHA from oily fish, krill or algae. Strong for lowering triglycerides; mixed for general heart protection; some cautions apply.
Fats & oils
Panax (Korean/Asian) ginseng
A traditional East Asian root used for energy and mental sharpness. Evidence is mixed and modest, and it interacts with several common medicines.
Herbs & adaptogens
Phosphatidylserine
Phosphatidylserine is a fatty compound in cell membranes sold for memory and stress. Evidence is modest and mostly older, using bovine-derived forms no longer sold.
Brain & cognition
Potassium
An essential electrolyte best obtained from food. Over-the-counter supplements are capped low in the UK because too much can disturb the heart.
Minerals
PQQ (pyrroloquinoline quinone)
PQQ is a vitamin-like compound marketed for mitochondria and brain health. Human evidence is small and early, and most claims rest on lab and animal work.
Longevity & mitochondrial
Prebiotic fibre
Fermentable fibres that feed gut bacteria. Can help regularity for some people, but often cause gas and bloating, especially at the start.
Gut & digestion
Probiotics
Live microbes sold for gut health. Some specific strains have decent evidence for specific problems; "probiotic" as a general label tells you very little.
Gut & digestion
Psyllium husk
A gel-forming fibre with some of the best evidence among gut supplements for constipation, stool consistency and modest cholesterol lowering.
Gut & digestion
Quercetin
Quercetin is a plant flavonoid found in onions and apples. Supplements are used for inflammation and immunity, but evidence is modest and absorption is limited.
Longevity & mitochondrial
Resveratrol
Resveratrol is a plant compound from grape skins and knotweed. It generated huge hype for anti-ageing, but human evidence is mixed and absorption is poor.
Longevity & mitochondrial
Rhodiola rosea
An arctic root herb used for fatigue and stress. Evidence is limited and mixed, with small trials, though it is generally well tolerated at normal doses.
Herbs & adaptogens
Saffron extract
A spice extract with some of the better small-trial support among herbs for low mood and anxiety. Evidence is encouraging but not conclusive.
Herbs & adaptogens
SAMe (S-adenosyl methionine)
SAMe is a compound the body makes naturally and is sold for low mood and joint pain. Evidence is mixed, and it carries real cautions for serotonin and mania.
Sleep, stress & mood
Selenium
A trace mineral needed for thyroid and antioxidant enzymes. UK intake is often on the low side, but the gap between enough and too much is narrow.
Minerals
Shilajit
A tar-like substance from mountain rocks sold for energy and testosterone. Limited human data and a real risk of heavy metal contamination.
Herbs & adaptogens
Spermidine
Spermidine is a natural polyamine found in wheat germ and soya. It promotes autophagy in lab studies, but human evidence for longevity is early and limited.
Longevity & mitochondrial
St John's wort
A herbal remedy for low mood that interacts with a huge number of medicines, including the contraceptive pill and antidepressants.
Herbs & adaptogens
Taurine
A sulphur-containing amino acid found in energy drinks and meat. Some promising heart and exercise findings, but evidence is still early.
Amino acids & derivatives
Tongkat ali
A Southeast Asian root sold as a testosterone and libido booster. Small studies hint at benefits, but quality problems and thin evidence are the catch.
Hormonal & sexual health
Tribulus terrestris
Tribulus is a herb marketed as a testosterone booster, but human trials generally show no meaningful rise in testosterone. Evidence for libido is limited.
Hormonal & sexual health
Turmeric / curcumin
Curcumin is the main active compound in turmeric. It is poorly absorbed, has modest joint evidence, and has been linked to rare cases of liver injury.
Herbs & adaptogens
Urolithin A
Urolithin A is a gut-made compound from pomegranate and nuts that may support mitochondria. Early human trials look promising but small and company-linked.
Longevity & mitochondrial
Valerian root
A traditional herbal sleep aid with mixed evidence. Generally safe short term, with a distinctive smell and some caution points.
Sleep, stress & mood
Vitamin A
Vitamin A supports vision, skin and immunity, but too much retinol can harm bones, the liver and an unborn baby. Pregnant women are advised to avoid supplements.
Vitamins
Vitamin B12
B12 is essential for nerves and red blood cells. Vegans and people with absorption problems often need it; for everyone else, extra rarely boosts energy.
Vitamins
Vitamin C
Vitamin C is an essential water-soluble vitamin. Most people get enough from food; extra mostly adds expensive urine, though it may slightly shorten colds.
Vitamins
Vitamin D3 (cholecalciferol)
Vitamin D3 is the form your skin makes from sunlight. In the UK, many people are low in winter, and a daily supplement is widely recommended in autumn and winter.
Vitamins
Vitamin E
Vitamin E is a fat-soluble antioxidant. Deficiency is rare, and large-dose supplements have not delivered the heart or cancer benefits once hoped for.
Vitamins
Vitamin K2 (MK-4 / MK-7)
Vitamin K2 helps direct calcium into bones and away from soft tissue. It is popular alongside vitamin D, but the evidence for supplements is still developing.
Vitamins
Whey protein
A fast-digesting milk protein. A convenient way to hit protein targets; it helps muscle growth only when your overall protein intake is otherwise short.
Protein & performance
Zinc
An essential trace mineral for immunity, skin and wound healing. Useful if you are low, but too much for too long can cause copper deficiency.
Minerals