L-Valine
Summary
Valine is one of the three branched-chain amino acids people must get from food; adults need about 24 mg per kg of body weight daily. Small lab studies giving 3–10 g of valine alone found no effect on blood sugar, appetite or food intake (grade D). Its only reported benefit, less exercise fatigue, came from a three-amino-acid mix.
Key facts
- Estimated average requirement 19 mg/kg/day; RDA 24 mg/kg/day (31 mg/kg/day in pregnancy)[1]
- Only short laboratory studies in healthy men (single 3.3–10 g doses); none tested valine supplements over weeks[2][3]
- 10 g valine did not lower post-meal glucose and raised glucagon, unlike leucine and isoleucine[2]
- Prescribed valine supplements are part of dietary management of maple syrup urine disease, a rare inherited disorder[7]
- People with cirrhosis cleared an oral valine load more slowly than controls[5]
- 3 graded human outcomes on this page
- October 13, 2026
How it works
EstablishedValine is used to build body proteins and can be broken down for energy in muscle. Unlike leucine and isoleucine, it did not lower post-meal glucose in a human study, and it raised glucagon. Higher blood BCAA levels track with insulin resistance in people with obesity; in rats, added BCAAs contributed to insulin resistance on a high-fat diet but not on standard chow.[1][2][6]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Fatigue | Grade D | Improved | Crossover RCT · n = 39 · 2019 | 1 row |
| Blood sugar | Grade D | No effect | Crossover RCT · n = 15 · 2021 | 1 row |
| Appetite | Grade D | No effect | Crossover RCT · n = 12 · 2019 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Perceived fatigue during a 2-hour cycling session (amino acid mix) | Improved | Grade D | Crossover RCT · n = 39 · 2019 Healthy men (Japan) Form: Mix of arginine 3,600 mg, valine 2,200 mg and serine 200 mg · Dose: Daily mix (2,200 mg valine) · Duration: 14 days per period, 2-week washout Feeling of fatigue (visual analogue scale) and perceived exertion were lower than with placebo; serum ketone rise and the tryptophan-to-BCAA ratio were also lower. | 30999554 (opens PubMed)Source [4] |
| Post-meal glucose, insulin (C-peptide), glucagon and gastric emptying | No effect | Grade D | Crossover RCT · n = 15 · 2021 Healthy young men (Australia) Form: L-valine (also leucine and isoleucine arms) · Dose: 10 g by intragastric tube 30 minutes before a mixed-nutrient drink · Duration: Single dose per visit Valine did not lower post-meal glucose and raised glucagon versus control; leucine and isoleucine lowered peak glucose compared with both control and valine. No amino acid changed overall gastric emptying. | 34064996 (opens PubMed)Source [2] |
| Energy intake, appetite and blood glucose | No effect | Grade D | Crossover RCT · n = 12 · 2019 Healthy lean men (Australia) Form: L-valine · Dose: 3.3 g or 9.9 g infused into the duodenum over 90 minutes · Duration: Single infusion per visit Neither dose changed gut motility, cholecystokinin, blood glucose, appetite, symptoms or the amount eaten at a buffet meal. | 30621276 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Free-form L-valine (powder or capsules) | Varies[8] | An oral valine load raised blood valine within the test period in healthy controls and, to higher and longer-lasting levels, in people with cirrhosis.[5] | Gastrointestinal symptoms did not differ from saline with 3.3–9.9 g infused into the small intestine.[3] | Glucose, appetite and gut-hormone laboratory studies (single doses) |
| BCAA blends (leucine, isoleucine, valine) | Varies[2] | No head-to-head human data on valine absorption from blends versus free valine.[2] | Not assessed in the valine studies cited here.[2][3] | Muscle and exercise outcomes (see BCAAs page) |
| Medical valine solutions (maple syrup urine disease) | Varies[7] | No absorption data; plasma leucine fell when children switched to the ready-to-use liquid, and the valine dose needed dropped by 30%.[7] | Well tolerated, with no adverse effects reported over 56 days in 5 children.[7] | Dietary management of maple syrup urine disease under a metabolic team |
Studied doses
Doses studied in human trials ranged from single 3.3–10 g doses of valine given by tube in laboratory studies, to 2.2 g/day for 14 days inside an arginine, valine and serine mix. No trial has tested valine alone by mouth over several weeks.[2][3][4]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- LevodopaPK studyLarge neutral amino acids compete with levodopa for transport into the brain: oral leucine, isoleucine or phenylalanine (100 mg/kg) reversed levodopa's effect in people with Parkinson's disease. Valine is also a large neutral amino acid but was not tested.[9]
Who should be careful
- Maple syrup urine disease
- Valine intake in this inherited disorder is set and monitored by a metabolic team; over-the-counter products are not a substitute.[7]
- Liver cirrhosis
- People with cirrhosis showed higher and slower-clearing blood valine after an oral load, suggesting reduced tolerance.[5]
- People taking levodopa
- Other large neutral amino acids blocked levodopa's effect in a 1984 study; valine belongs to the same large neutral amino acid group but was not tested.[9]
- Pregnancy and breastfeeding
- Requirements are higher (RDA 31 mg/kg/day in pregnancy, 35 mg/kg/day in lactation), but no trial has tested valine supplements in these groups.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- Label dose vs requirementA label serving of 2,000 mg once or twice daily (2–4 g) adds roughly 1.2–2.4 times the adult RDA for a 70 kg person on top of food.[8][1]
- Label dose vs studied doseThe only multi-day human study used 2.2 g/day of valine inside a mix with arginine and serine; single-dose studies of 3.3–10 g of valine alone showed no glucose or appetite effect.[4][2][3]
- Valine in BCAA blendsMost valine is sold inside BCAA blends; check the BCAAs page for blend ratios and exercise evidence.[2]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
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Frequently asked questions
How much valine do adults need?
The Institute of Medicine RDA is 24 mg per kg of body weight per day for adults, about 1.7 g for a 70 kg person, from all protein sources.[1]
Does valine supplementation build muscle?
No published trial has tested valine alone for muscle or strength. Studies of valine alone were single-dose lab tests of glucose and appetite.[2][3]
Does valine lower blood sugar?
Not in the available study: 10 g of valine before a drink did not lower post-meal glucose and raised glucagon, while leucine and isoleucine did lower peak glucose.[2]
Does valine reduce exercise fatigue?
A 14-day trial of a mix with arginine, valine and serine lowered perceived fatigue during cycling, but valine's own contribution is unknown and the trial was run by the manufacturer.[4]
Is valine safe?
Single 3.3–9.9 g infusions did not change symptoms compared with saline in healthy men. People with cirrhosis cleared valine more slowly, and valine in maple syrup urine disease is managed medically.[3][5][7]
Are high blood BCAA levels harmful?
Higher circulating BCAAs are linked with insulin resistance in people with obesity. In rats, added BCAAs contributed to insulin resistance on a high-fat diet but not on standard chow, so cause and effect in people is unproven.[6]
Sources
- [1]Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Appendix E: DRI values for indispensable amino acids by life stage and gender group. Institute of Medicine, National Academies Press, 2006. guideline
- [2]Comparative Effects of the Branched-Chain Amino Acids, Leucine, Isoleucine and Valine, on Gastric Emptying, Plasma Glucose, C-Peptide and Glucagon in Healthy Men.. Nutrients, 2021. crossover-RCT
- [3]Intraduodenal Administration of L-Valine Has No Effect on Antropyloroduodenal Pressures, Plasma Cholecystokinin Concentrations or Energy Intake in Healthy, Lean Men.. Nutrients, 2019. crossover-RCT
- [4]Combined Effect of Arginine, Valine, and Serine on Exercise-Induced Fatigue in Healthy Volunteers: A Randomized, Double-Blinded, Placebo-Controlled Crossover Study.. Nutrients, 2019. crossover-RCT
- [5]Evidence for valine intolerance in patients with cirrhosis.. Hepatology, 1984. PK-study
- [6]A branched-chain amino acid-related metabolic signature that differentiates obese and lean humans and contributes to insulin resistance.. Cell Metab, 2009. observational
- [7]Simplifying supplementation in MSUD: tolerance and acceptability of liquid valine and isoleucine supplements in maple syrup urine disease.. Orphanet J Rare Dis, 2026. open-label
- [8]L-Valine (BulkSupplements.com), DSLD label 254890: 2,000 mg L-valine per serving, once or twice daily. NIH Office of Dietary Supplements, Dietary Supplement Label Database, 2021. label
- [9]The "on-off" phenomenon in Parkinson's disease. Relation to levodopa absorption and transport.. N Engl J Med, 1984. PK-study
What changed
- Independent review: added the levodopa interaction (large neutral amino acid competition, Nutt 1984, PMID 6694694), flagged that valine itself was not tested. All PMIDs re-checked.
- Adversarial review pass: every evidence row, key fact, form, label line, FAQ and insight re-read against its PubMed abstract, PMC full text, fact sheet, FDA page or DSLD label; all PMIDs re-checked by esummary (titles and years match; no retraction or expression-of-concern flags). Fixed: gastric-emptying claim removed (no BCAA changed it), rat insulin-resistance finding restated precisely, tolerability restated as no difference from saline, BCAA-blend tolerance no longer cross-referenced without a source. Page set indexable.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year from the record) and abstracts read for each cited row. Requirement values from the Institute of Medicine DRI Essential Guide, Appendix E (adult EAR 19 and RDA 24 mg/kg/day). Label amounts from the NIH Dietary Supplement Label Database. No NIH ODS or NCCIH fact sheet covers valine on its own.