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Amino Acids & Proteins

Amino acids are the building blocks of proteins. In supplements, this category includes single amino acids and protein-derived ingredients such as creatine, collagen peptides, and branched-chain amino acids (BCAAs). Browse 32 entries in this category.

Fine protein powder and a measuring scoop on textured paper
Editorial illustration

Illustrated guides

Selected entries interpreted through varied editorial art and photography.

Pale collagen peptide powder and a translucent gel-like material study

Collagen Peptides

Hydrolyzed animal protein supplying glycine and proline, popular for skin hydration and joint support.Fine white creatine-like powder with a compact measuring scoop

Creatine

A compound made from amino acids that fuels short bursts of muscle power and is the most studied sports supplement in the world.Fine pale powder beside folded red athletic fabric and glassware

L-Carnosine

A muscle dipeptide sold for metabolic and healthy-aging goals, with mixed small-trial evidence.Gouache illustration of a looping metabolic pathway in muted colors

L-Ornithine

A non-protein amino acid in the urea cycle, marketed for fatigue and recovery on limited human evidence.White powder on a ceramic dish beside folded linen

L-Proline

A collagen-building amino acid whose biological importance does not establish a benefit from extra standalone supplements.Woodblock-style tea branch, loose leaves, and a small ceramic cup

L-Theanine

The calming amino acid in green tea — promotes relaxed focus without drowsiness, especially paired with caffeine.Cream-colored whey protein powder with a scoop and plain glass of milk

Whey Protein

The fast-digesting milk protein rich in leucine — the gold standard for muscle building and the world's best-selling protein powder.

Amino Acids & Proteins

  1. 015-HTPThe serotonin precursor from an African seed — modest mood and sleep evidence, with a serious antidepressant interaction warning.
  2. 02Acetyl-L-Carnitine (ALCAR)The brain-penetrant carnitine — an acetyl-group shuttle with genuine, if modest, cognitive and nerve-health data.
  3. 03AgmatineThe neurotransmitter-ish amino metabolite — a gym 'pump' staple with emerging pain and mood data on top.
  4. 04BCAAs (Branched-Chain Amino Acids)The three muscle-signaling amino acids — useful in specific fasted-training cases, overrated next to whole protein.
  5. 05Beta-AlanineThe tingling endurance amino acid — raises muscle carnosine to fight fatigue in efforts lasting 1–4 minutes.
  6. 06BetaineThe methyl-donor molecule from beets — evidence for homocysteine and liver support, with a sweet-salt taste and a big name.
  7. 07Casein ProteinMilk's slow-release protein — the overnight muscle-builder with a high-quality amino acid profile and a distinct digestion curve.
  8. 08Citrulline (L-Citrulline)The watermelon amino acid that raises nitric oxide — real endurance and pump benefits at 6–8 grams.
  9. 09Collagen PeptidesHydrolyzed animal protein supplying glycine and proline, popular for skin hydration and joint support.
  10. 10CreatineA compound made from amino acids that fuels short bursts of muscle power and is the most studied sports supplement in the world.
  11. 11D-Aspartic AcidThe test-booster amino acid that works in rodents and men with low baseline testosterone — and little else.
  12. 12Essential Amino Acids (EAAs)The nine that matter — free-form essentials trigger muscle protein synthesis without the calories of whole protein.
  13. 13GABAThe brain's brake pedal in pill form — a calming neurotransmitter whose supplement absorption remains genuinely debated.
  14. 14GlycineThe smallest amino acid with big jobs — sleep cooling, collagen building, and a gentle 3-gram bedtime dose.
  15. 15HMBLeucine's anti-catabolic daughter molecule — modest, genuine muscle-preservation effects in the right populations.
  16. 16L-ArginineThe nitric-oxide precursor — real but modest blood-pressure and blood-flow effects, often outshone by its cousin citrulline.
  17. 17L-CarnitineThe fat-transporter amino compound — essential for burning fat for energy, but a supplement that mostly helps when levels are low.
  18. 18L-CarnosineA muscle dipeptide sold for metabolic and healthy-aging goals, with mixed small-trial evidence.
  19. 19L-CysteineThe sulfur amino acid that builds glutathione and hair keratin — a building block whose acetylated cousin NAC gets the glory.
  20. 20L-GlutamineThe most abundant amino acid in the body — a hospital staple and a popular gut-health supplement with mixed exercise evidence.
  21. 21L-HistidineThe amino acid behind histamine and carnosine — an eczema-adjacent niche and a skin-barrier filaggrin precursor.
  22. 22L-LysineThe cold-sore amino acid — modest but real evidence for reducing herpes outbreaks, essential protein chemistry elsewhere.
  23. 23L-MethionineThe essential sulfur amino acid — methylation's starting material and a liver-support niche, with balance caveats.
  24. 24L-OrnithineA non-protein amino acid in the urea cycle, marketed for fatigue and recovery on limited human evidence.
  25. 25L-PhenylalanineThe dopamine-precursor amino acid — mood and focus claims with mixed evidence, and one absolute genetic contraindication.
  26. 26L-ProlineA collagen-building amino acid whose biological importance does not establish a benefit from extra standalone supplements.
  27. 27L-TheanineThe calming amino acid in green tea — promotes relaxed focus without drowsiness, especially paired with caffeine.
  28. 28L-TryptophanThe essential amino acid behind serotonin — evidence for sleep and mood, with a tragic 1989 contamination scandal in its history.
  29. 29L-TyrosineThe dopamine-precursor amino acid that helps under acute stress and sleep deprivation — less useful day-to-day.
  30. 30Pea ProteinThe plant-protein workhorse — allergen-friendly, amino-acid-solid, and nearly whey's equal for muscle building.
  31. 31TaurineThe most abundant amino acid in the heart and retina — the 'energy drink amino acid' with real cardiovascular research.
  32. 32Whey ProteinThe fast-digesting milk protein rich in leucine — the gold standard for muscle building and the world's best-selling protein powder.