Performance
L-Carnitine
Also known as: L-Carnitine, Acetyl-L-Carnitine, L-Carnitine L-Tartrate, L-carnitine tartrate
Shuttles fatty acids into mitochondria for energy. Supports fat burning and exercise performance.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every L-Carnitine product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nootropics Depot Acetyl L-Carnitine HCL (ALCAR) Capsules | 94 A | $0.22 |
| 2 | Nutricost Acetyl L-Carnitine Powder | 94 A | $0.08 |
| 3 | Nootropics Depot Acetyl L-Carnitine ALCAR Powder | 94 A | — |
| 4 | Jarrow Formulas Acetyl L-Carnitine 500 mg | 94 A | $0.38 |
| 5 | Nutricost Acetyl L-Carnitine Capsules | 94 A | $0.12 |
| 6 | Momentous Acetyl L-Carnitine | 94 A | $0.50 |
| 7 | NutraBio Acetyl L-Carnitine (500mg) | 94 A | $0.44 |
| 8 | Thorne Acetyl-L-Carnitine | 92 A | $0.53 |
| 9 | Pure Encapsulations Acetyl-l-Carnitine | 92 A | $0.75 |
| 10 | Natural Factors Acetyl-L-Carnitine | 92 A | $0.70 |
| 11 | Pure Encapsulations Cognitive Aminos | 91 A | $0.98 |
| 12 | Pure Encapsulations CogniPhos | 91 A | $1.25 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much L-Carnitine should I take?
The typical range is 1-3g daily. Daily for chronic effects
When should I take L-Carnitine?
With carbs and insulin for uptake. Yes, with carbs.
Which form of L-Carnitine is best?
L-Carnitine L-Tartrate (LCLT) — Best for exercise. Other forms in the catalog: Acetyl-L-Carnitine (ALCAR), L-Carnitine, ALCAR, L-carnitine tartrate, GPLC.
Is L-Carnitine safe?
Commonly reported: GI upset, Fishy body odor. Serious warnings: TMAO concerns debated. No concerns
Which L-Carnitine supplement scores highest?
Nootropics Depot Acetyl L-Carnitine HCL (ALCAR) Capsules, at 94/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
1000 mg / dayL-Carnitine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
L-Carnitine dosage reference →Primary uses
- Fat metabolism
- Recovery
- Heart health
- Exercise capacity
- Energy
- Exercise performance
What systematic reviews concluded
Outcomes that systematic reviews of L-Carnitine reached a verdict on: 4 with a benefit, 2 with no effect, 1 unclear. Each is quoted from a review and linked to it on PubMed. How these were read.
Reviews found a benefit (4)
“Carnitine supplementation significantly reduced fasting blood sugar (FBS; WMD -2.93 mg/dL, 95 % CI -5.20 to -0.65), fasting insulin (WMD -3.54 μU/mL, 95 % CI -7.00 to -0.07), and HOMA-IR (WMD -0.69, 95 % CI -1.26 to -0.13), but had no significant effect on QUICKI.” PMID 41177307
“L-carnitine was regarded as the best treatment method for enhancing sperm motility.” PMID 40813743 · 2 reviews
“Both LC and NAC can improve sperm motility, sperm concentration, and normal morphology, and increase serum testosterone concentration, but have no significant effect on other serum hormones.” PMID 40350672
“The findings of this umbrella meta-analysis support that supplementation of L-carnitine supplementation can successfully manage weight, BMI, and WC reduction.” PMID 40298161 · 2 reviews
Reviews found no effect (2)
“Carnitine supplementation significantly reduced fasting blood sugar (FBS; WMD -2.93 mg/dL, 95 % CI -5.20 to -0.65), fasting insulin (WMD -3.54 μU/mL, 95 % CI -7.00 to -0.07), and HOMA-IR (WMD -0.69, 95 % CI -1.26 to -0.13), but had no significant effect on QUICKI.” PMID 41177307
“Both LC and NAC can improve sperm motility, sperm concentration, and normal morphology, and increase serum testosterone concentration, but have no significant effect on other serum hormones.” PMID 40350672
Not enough to say: cardiovascular outcomes in coronary artery disease.
2 findings from reviews in specific patient groups (such as cancer, pregnancy or surgery) are not shown here.
How it works
- Shuttles fatty acids to mitochondria
- Reduces muscle damage
- Supports energy production
Dosage
- Typical range
- 1-3g daily
- Timing
- With carbs and insulin for uptake
- With food
- Yes, with carbs
- Duration
- Daily for chronic effects
- Special populations
- Endurance athletes, fat loss, elderly
Forms
- L-Carnitine L-Tartrate (LCLT)
- Acetyl-L-Carnitine (ALCAR)
- ALCAR
- L-carnitine tartrate
- GPLC
Safety
Common side effects
- GI upset
- Fishy body odor
Contraindications
- Seizure disorders
- Hypothyroidism
Products containing L-Carnitine
Top-scoring supplements in our catalog that list L-Carnitine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Good evidence for recovery and fat oxidation
Grade B: Some human trials support key claims; further confirmation needed.
Cited research for L-Carnitine
Clinical studies referenced across Formulate guides that mention l-carnitine. Each links to the full study page with PubMed source + the guides that cite it.
- Sima AA, Calvani M, Mehra M, Amato A (2005)Diabetes Care
Acetyl-L-carnitine for the treatment of diabetic peripheral neuropathy: a long-term, randomised, double-blind, placebo-controlled study
- Montgomery SA, Thal LJ, Amrein R (2003)International Clinical Psychopharmacology
Acetyl-L-carnitine for the treatment of mild cognitive impairment and mild Alzheimer's disease: a meta-analysis of clinical trials
Related in Performance
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.