L-Alanine
Summary
L-alanine is a non-essential amino acid that the liver converts to glucose. Human studies are small and old: a 40 g bedtime dose with glucose reduced overnight lows in 15 people with type 1 diabetes under supervision, and an alanine drink did not help cyclists (grade D). It is not the same as beta-alanine, the carnosine-building sports supplement.
Key facts
- A non-essential amino acid that the liver uses to make glucose[9]
- Beta-alanine is a different molecule studied for muscle carnosine; trials on it do not apply to L-alanine[8]
- An alanine drink during prolonged cycling did not improve, and possibly worsened, time-trial performance in 8 cyclists[4]
- 4 graded human outcomes on this page
- October 13, 2026
How it works
EstablishedThe liver converts alanine into glucose, a process glucagon speeds up. In people with type 1 diabetes, oral alanine raised glucagon and blood glucose. Mouse and cell work suggests it also activates the liver energy sensor AMPK; that has not been tested in people.[9][1][7]
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 |
|---|---|---|---|---|
| Rehydration | Grade D | No effect | RCT · n = 129 · 1991 | 2 rows |
| Blood sugar | Grade D | Improved | Crossover RCT · n = 15 · 1997 | 1 row |
| Exercise | Grade D | Worsened | Crossover RCT · n = 8 · 2014 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Duration of diarrhea in children with alanine rehydration solution | No effect | Grade D | RCT · n = 129 · 1991 Boys aged 3–48 months with acute non-cholera diarrhea and mild-moderate dehydration Form: Oral rehydration solution with 90 mmol/L alanine and reduced glucose · Dose: Offered at 120 mL/kg for 6 hours, then to replace stool losses · Duration: Until recovery Urine output in the first 6 hours was higher, but duration of diarrhea, solution intake and stool output did not differ significantly from standard WHO solution. | 1865280 (opens PubMed)Source [6] |
| Stool output with alanine-glucose rehydration solution in severe diarrhea | Improved | Grade D | RCT · n = 97 · 1989 Males aged 6–59 with severe dehydration from cholera or E. coli diarrhea, treated in hospital Form: WHO glucose oral rehydration solution with L-alanine added · Dose: Concentration not stated in the abstract · Duration: Until diarrhea stopped Median 24-hour stool output fell from 309 to 196 mL/kg, and 2 versus 18 patients needed unscheduled IV fluids. | 2502251 (opens PubMed)Source [5] |
| Overnight low blood sugar episodes in type 1 diabetes (bedtime alanine) | Improved | Grade D | Crossover RCT · n = 15 · 1997 Adults with insulin-dependent (type 1) diabetes given evening NPH insulin Form: L-alanine plus 10 g glucose · Dose: 40 g alanine at bedtime (about 200 kcal with the glucose) · Duration: Single nights, four randomized occasions Glucose of 40 mg/dL or less occurred on 1 occasion with alanine plus glucose versus 13 occasions with no treatment and 10 with a milk-and-toast snack (P<0.02). | 9250445 (opens PubMed)Source [3] |
| 30-km cycling time trial after prolonged exercise (alanine drink) | Worsened | Grade D | Crossover RCT · n = 8 · 2014 Trained male cyclists Form: L-alanine drink during exercise (compared with whey protein and placebo) · Dose: Dose not stated in the abstract · Duration: 120 minutes of steady cycling, then a 30-km time trial Time-trial performance was 'possibly harmed' (about 2.1%) with alanine versus placebo; heart rate was slightly lower during steady cycling. | 24937205 (opens PubMed)Source [4] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| L-alanine powder or capsules | Varies[2] | Oral alanine raised blood glucose within 30 minutes in people with type 1 diabetes during induced low blood sugar, showing it is absorbed quickly.[2] | No human trial of L-alanine as a daily supplement reporting tolerability was found; the cited studies were short, supervised sessions.[1][2][3] | Blood-sugar studies in type 1 diabetes (20–40 g single doses) |
| Alanine-containing oral rehydration solution | Varies[5][6] | Used as a hospital rehydration fluid rather than a supplement.[5][6] | The abstracts report no safety problems specific to alanine.[5][6] | Acute diarrhea with dehydration (adults and young children) |
Studied doses
Doses studied in human trials ranged from 20 to 40 g of L-alanine as single oral doses (40 g was paired with 10 g of glucose at bedtime). Rehydration trials added alanine to oral rehydration solution at up to 90 mmol/L. No long-term daily-use trial was found.[1][2][3][6]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- People on insulin or diabetes medicines
- Oral alanine raised blood glucose by several mmol/L in people with type 1 diabetes. The studies were run under medical supervision with glucose monitoring.[1][2][3]
- Pregnancy, breastfeeding and children
- No supplement trial in these groups was found. The children's study tested a hospital rehydration solution, not a supplement.[6]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
Frequently asked questions
Is L-alanine the same as beta-alanine?
No. Beta-alanine raises muscle carnosine and is studied for high-intensity exercise. L-alanine is the ordinary protein-building amino acid, and its human trials are about blood sugar and rehydration.[8][1][5]
Does L-alanine raise blood sugar?
Yes. In people with type 1 diabetes, 20–40 g by mouth raised glucagon and blood glucose, with a slower but longer-lasting rise than oral glucose during induced low blood sugar.[1][2]
Does L-alanine help exercise performance?
The one trial found here says no: an alanine drink during 2 hours of cycling possibly worsened the following time trial by about 2%.[4]
Sources
- [1]Glycemic actions of alanine and terbutaline in IDDM.. Diabetes Care, 1993. crossover-RCT
- [2]Alanine and terbutaline in treatment of hypoglycemia in IDDM.. Diabetes Care, 1993. PK-study
- [3]Alanine and terbutaline in the prevention of nocturnal hypoglycemia in IDDM.. Diabetes Care, 1997. crossover-RCT
- [4]Cycling time trial performance may be impaired by whey protein and L-alanine intake during prolonged exercise.. Int J Sport Nutr Exerc Metab, 2014. crossover-RCT
- [5]Oral rehydration formula containing alanine and glucose for treatment of diarrhoea: a controlled trial.. BMJ, 1989. RCT
- [6]Alanine-based oral rehydration solution: assessment of efficacy in acute noncholera diarrhea among children.. J Pediatr Gastroenterol Nutr, 1991. RCT
- [8]Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity.. Amino Acids, 2007. RCT
- [9]Gluconeogenesis from alanine in normal postabsorptive man. Intrahepatic stimulatory effect of glucagon.. Diabetes, 1975. PK-study
- [7]l-Alanine activates hepatic AMP-activated protein kinase and modulates systemic glucose metabolism.. Mol Metab, 2018. animal-study
What changed
- Adversarial review pass: every evidence row's numbers re-checked against its abstract (Europe PMC for abstracts PubMed truncates, PMC full text where open), grades checked against the grading rubric, and safety and overclaim wording re-read. No changes needed.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Strict second-pass self review (no separate reviewer agent was available for this batch): every PMID re-fetched via esummary and every evidence row, dose and safety line re-read against its abstract or fact sheet. Confirmed that no NIH ODS or NCCIH fact sheet covers L-alanine. Beta-alanine trials were excluded because they test a different compound. The rehydration trials are labelled as medical solutions, not supplements. Retraction and erratum flags checked on all PMIDs: none.