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⚠ Child with hypoketotic hypoglycemia + cardiomyopathy — screen for primary carnitine deficiency [2]
⚠ Hemodialysis patient with persistent fatigue/weakness — check carnitine levels [2]
⚠ Patient on valproic acid — VPA depletes carnitine; consider supplementation [2]
⚠ ALCAR for cognitive; L-carnitine for cardiac/exercise; propionyl-L-carnitine for PAD [2]
🥗 Food first — build your daily Typical 500–2,000 mg
Check the foods you regularly eat — the bar fills toward your daily target.
Ground beef (85 g)80 mg
Milk (240 mL)8 mg
Chicken breast (85 g)3 mg
Cheese, cheddar (28 g)2 mg
Whole wheat bread (1 slice)0.2 mg
Asparagus (100 g)0.2 mg
Check your regular foods above
☑ Risk checker
Primary carnitine deficiency (OCTN2 mutation — autosomal recessive) [2]
Chronic hemodialysis (carnitine losses) [2]
Premature birth (immature synthesis) [2]
Valproic acid therapy (inhibits carnitine transport) [2]
Strict veganism (very low dietary intake) [1]
Select factors
🔬 Lab interpreter
Recommended test
Plasma free and total carnitine
Plasma free and total carnitine
Reference range / target
Free carnitine 25–50 µmol/L
Free carnitine 25–50 µmol/L
Free:total ratio <0.25 suggests carnitine depletion [2].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
L-Carnitine is essential for mitochondrial fatty acid transport, but supplementation in replete individuals does NOT increase fat burning. ALCAR crosses the BBB (cognitive). Post-MI meta-analysis: 27% mortality reduction. The TMAO concern is real but debated. Primary carnitine deficiency (genetic) is life-threatening — levocarnitine is the treatment. Marketing for weight loss far exceeds evidence [1] [2] [3].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Physiologically important. Levels decline in pregnancy. Standard diet adequate. Supplementation data limited [1].
👦 Pediatric: See guidance
Conditionally essential in premature neonates. Added to some pediatric TPN formulations. Primary carnitine deficiency (genetic) requires lifelong levocarnitine replacement [2].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Empty stomach for best absorption. Can split into 2 doses [1].
💊 With food: Better absorbed on empty stomach [1].
🚫 Avoid: Megadose >3 g/day may increase TMAO production [3].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['L-Carnitine (or L-carnitine tartrate)', 'common', 'Standard form. 500–2,000 mg/day. Used for exercise and general supplementation [1].'] | Standard | Check label | |
| ['Acetyl-L-carnitine (ALCAR)', 'preferred', 'Acetylated form. Crosses BBB better. Used for cognitive/neurological applications [2].'] | Standard | Check label | |
| ['Propionyl-L-carnitine', '', 'Used for peripheral vascular disease and cardiac applications [2].'] | Standard | Check label | |
| ['Levocarnitine (Carnitor)', '', 'Prescription for primary/secondary carnitine deficiency and hemodialysis [2].'] | Standard | Check label |
3 Common questions
Does L-carnitine burn fat? ▼
L-carnitine transports fatty acids into mitochondria for beta-oxidation — this is true. But supplementing L-carnitine in individuals with adequate levels does NOT increase fat burning. Your body already has enough carnitine to perform its transport function [1]. The weight loss marketing far exceeds the evidence.
What is the TMAO concern? ▼
Gut bacteria convert L-carnitine to TMA, which the liver converts to TMAO. TMAO has been associated with increased cardiovascular risk in observational studies [3]. The clinical significance is debated — the post-MI meta-analysis actually showed BENEFIT from L-carnitine despite the TMAO concern.
ALCAR vs L-carnitine — when to use which? ▼
Do vegans need carnitine supplements? ▼
Vegans have ~20–30% lower plasma carnitine than omnivores, but kidney reabsorption compensates [1]. No clinical carnitine deficiency has been documented in healthy adult vegans. Supplementation is optional but reasonable.
4 Clinical evidence
Strong
Mitochondrial fatty acid transport: carnitine is absolutely required for long-chain fatty acid beta-oxidation — this is biochemistry [1]. Treatment of primary carnitine deficiency (genetic OCTN2 mutation): levocarnitine is life-saving [2]. Hemodialysis: IV carnitine replacement is standard for carnitine depletion on dialysis [2]. HIGH
Moderate
Cardiovascular: meta-analysis of 13 RCTs (n=3,629) in post-MI patients showed reduced all-cause mortality (27%), ventricular arrhythmias (65%), and angina (40%) with L-carnitine supplementation [2]. Peripheral neuropathy (diabetic): ALCAR improved nerve conduction in some trials [2]. Male fertility: some evidence for improved sperm parameters [2]. Exercise performance: inconsistent; may benefit in older adults more than young athletes [1]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Relative
⚠ Seizure disorder — may increase seizure frequency
⚠ Hypothyroidism — can antagonise peripheral thyroid hormone action
⚠ Concurrent warfarin — may potentiate anticoagulation
⚠ End-stage renal disease/dialysis — use the medically indicated form; raises TMAO
🚩 Red flags
● Child with unexplained cardiomyopathy + hypoglycemia — primary carnitine deficiency [2]
● Patient on valproic acid with muscle weakness — check carnitine [2]
● Patient on warfarin starting L-carnitine — monitor INR [2]
6 Interactions
Drug interactions
Warfarin Moderate
Mechanism: L-carnitine may enhance warfarin effect through uncertain mechanism. [2]
Effect: Increased INR, bleeding risk. [2]
Action: Monitor INR when starting L-carnitine [2].
Valproic acid Moderate
Mechanism: VPA inhibits carnitine transport and increases renal excretion. [2]
Effect: Secondary carnitine deficiency. Hepatotoxicity risk increases. [2]
Action: Consider carnitine supplementation during VPA therapy, especially in children [2].
Thyroid hormones (L-thyroxine) Moderate
Mechanism: L-carnitine inhibits thyroid hormone entry into cell nucleus. Used therapeutically for thyroid storm [2].
Effect: May reduce thyroid hormone activity. [2]
Action: Monitor thyroid function. L-carnitine has been used as adjunct treatment for thyrotoxicosis [2].
Supplement synergies
CoQ10 · 100–300 mg CoQ10
Both support mitochondrial function: carnitine (fatty acid transport) + CoQ10 (electron transport chain) [2].
Both support mitochondrial function: carnitine (fatty acid transport) + CoQ10 (electron transport chain) [2].
Alpha-Lipoic Acid · 300–600 mg ALA
Mitochondrial antioxidant. The carnitine-ALA-CoQ10 triad is a comprehensive mitochondrial support stack [2].
Mitochondrial antioxidant. The carnitine-ALA-CoQ10 triad is a comprehensive mitochondrial support stack [2].
7 Regulatory
United States (FDA): Levocarnitine (Carnitor): FDA-approved Rx for primary/secondary carnitine deficiency and dialysis. L-carnitine: dietary supplement [2].
European Union: Available as supplement and pharmaceutical [2].
South Korea: Available as dietary supplement and pharmaceutical.
8 US supplement products
491
on-market products containing L-Carnitine (NIH DSLD)
Brands carrying L-Carnitine (177)
Click a brand to see its L-Carnitine products.
9 Frequently paired with
10 References (4)
[1]National Institutes of Health, Office of Dietary Supplements. Carnitine — Fact sheet for health professionals. Updated 2024. ods.od.nih.gov REVIEW Accessed: 2026-05-29
[2]Longo N, et al. Carnitine transport and fatty acid oxidation. Biochim Biophys Acta. 2016;1863(10):2422-2435. doi:10.1016/j.bbamcr.2016.01.023 REVIEW Accessed: 2026-05-29
[3]Koeth RA, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med. 2013;19(5):576-585. doi:10.1038/nm.3145 REVIEW Accessed: 2026-05-29
[4]U.S. Department of Agriculture. FoodData Central. fdc.nal.usda.gov GOVERNMENT Accessed: 2026-05-29
11 Related articles
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12 Cite this page
Vancouver: Pkhakadze G. L-Carnitine — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Jun 02]. Available from: https://supplement.ge/ingredients/l-carnitine/
APA 7th: Pkhakadze, G. (2026). L-Carnitine — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/l-carnitine/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: December 2026
References: 4 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "L-Carnitine — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/l-carnitine/ CC BY 4.0.
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Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG