L-Carnitine Dosage: Per-Form Doses (LCLT 2 g, ALCAR 1.5-3 g, PLC 2 g)
Educational summary — not medical advice. See does it work for the fishy-odor/seizure, thyroid, and coumarin-anticoagulant cautions, and the TMAO open question.
The honest answer
There's no single carnitine dose — there's a dose per form, and you should match the form to your goal first. LCLT (exercise) ~2 g/day (Stefan 2021). ALCAR (brain/nerve) 1.5–3 g/day (Montgomery 2003). PLC (circulation) ~2 g/day (Kamoen 2021). The catch: a 500 mg capsule is only ~¼ of a 2 g dose, so a bottle's milligram number tells you less than servings-per-container does.
Dose by form — because the trials used different forms
The reason there's no universal number is that each carnitine form was studied on its own molecule at its own dose. Dosing an ALCAR product to LCLT's exercise research, or vice versa, mixes up the evidence. Here's what the trials actually used:
| Form | Goal | Studied dose | Source |
|---|---|---|---|
| LCLT (L-carnitine L-tartrate) | Exercise recovery | ~2 g/day for several weeks | Stefan 2021 |
| ALCAR (acetyl-L-carnitine) | Cognition / neuropathic pain | 1.5–3 g/day | Montgomery 2003; Li 2015 |
| PLC (propionyl-L-carnitine) | Circulation / claudication | ~2 g/day | Kamoen 2021 |
| Plain L-carnitine | General / heart | ~2 g/day (typical) | DiNicolantonio 2013 |
Dose calculator: how many servings to hit your form's dose?
Pick the form that matches your goal, then enter the label's carnitine per serving and how many servings you plan to take a day. You'll see your daily grams and what % of that form's studied dose you're actually getting.
Where to find the number: the Supplement Facts panel lists the carnitine per serving (e.g. "L-carnitine L-tartrate 1,000 mg" or "acetyl-L-carnitine 500 mg"). Enter that milligram figure — not the whole-capsule weight.
How to take it
- Match the form to the goal first. Exercise → LCLT ~2 g/day. Brain/nerve → ALCAR 1.5–3 g/day. Circulation → PLC ~2 g/day. See which form.
- Split it and take it daily. Effects build over weeks; two doses with meals is common, and a carbohydrate-containing meal may aid muscle uptake. Exact workout timing isn't critical.
- Watch servings-per-container, not just the mg. A 500 mg-per-serving product needs 4 servings for 2 g; a 1,000 mg one needs 2. Powders and 1,000 mg products usually cost less per gram.
- Don't chase higher. Around 3 g/day can cause a fishy body odor (NIH ODS), and the long-term TMAO question is unresolved — there's little reason to exceed your form's studied dose.
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Frequently asked questions
How much should I take per day?
By form: LCLT ~2 g/day (exercise), ALCAR 1.5–3 g/day (brain/nerve), PLC ~2 g/day (circulation). A common target is ~2 g/day — but match the form to your goal first. A 500 mg capsule is only ~¼ of a 2 g dose.
How many capsules equal a full dose?
Divide. At 500 mg/serving you need 4 servings for 2 g; at 1,000 mg/serving, 2. The front-of-bottle mg number alone is misleading — powders and 1,000 mg products reach the dose in fewer servings and cost less per gram.
When should I take it?
Daily, often split with meals; effects build over weeks. A carb-containing meal may aid uptake. Precise workout timing isn't critical — day-to-day consistency matters more.
Can you take too much?
The studied range is well tolerated, but ~3 g/day can cause a fishy body odor plus nausea (NIH ODS), and the long-term TMAO question is unresolved — little reason to exceed your form's dose.
Related
- Which form do I need? — LCLT vs ALCAR vs PLC, matched to your goal
- Best L-carnitine — every product by form and cost per gram
- Does it work? — form-labeled evidence + TMAO and safety
Sources
- Stefan M, et al. "L-Carnitine Tartrate Supplementation for 5 Weeks Improves Exercise Recovery." Nutrients. 2021. PMID: 34684429 (LCLT ~2 g/day).
- Montgomery SA, et al. "Acetyl-L-carnitine vs placebo in mild cognitive impairment and mild Alzheimer's disease." Int Clin Psychopharmacol. 2003. PMID: 12598816 (ALCAR 1.5–3 g/day).
- Kamoen V, et al. "L-carnitine for the treatment of intermittent claudication" (Cochrane). 2021. PMID: 34954832 (PLC ~2 g/day).
- NIH Office of Dietary Supplements. "Carnitine — Health Professional Fact Sheet." ods.od.nih.gov (fishy odor ~3 g/day, seizure caution — gov source, not an RCT).
- Full product dataset: /l-carnitine/cost-by-brand.json (CC BY 4.0).