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アミノ酸臨床用量 · 1500–3000mg/day (every positive trial reviewed used at least 1.5g/day)効果発現時間 · Benefit apparent by 3 months in MCI trials — the shortest trials reviewed ran 3 months

Acetyl-L-Carnitine (ALCAR)

A 2003 meta-analysis of double-blind RCTs (Montgomery et al.) found a modest but significant advantage for ALCAR over placebo in mild cognitive impairment and mild Alzheimer's disease at 1.5–3g/day, apparent by 3 months and growing over time. A 2018 meta-analysis of 12 RCTs (Veronese et al., n=791) found a large reduction in depressive symptoms, comparable to antidepressants with fewer adverse effects, most clearly in older adults. A 2022 RCT in pre-frail older adults (3g/day) improved MMSE and walking distance. A 2020 critical review still calls its role in dementia "under debate". No healthy-young-adult trial was found.

By The Nootropic Lab editorial teamUpdated 8 min read✓ Fact-checked

エビデンス確認日:

作用機序

Acetyl-L-Carnitine (ALCAR) is an acetylated form of L-Carnitine that crosses the blood-brain barrier more effectively than plain L-Carnitine. It works via three mechanisms: (1) donating acetyl groups for acetylcholine synthesis, supporting cholinergic neurotransmission; (2) transporting long-chain fatty acids into mitochondria for beta-oxidation, providing cellular energy to neurons; (3) supporting mitochondrial membrane integrity and reducing oxidative damage in aging neurons.

臨床エビデンスの概要

A 2003 meta-analysis of double-blind RCTs (Montgomery et al.) found a modest but significant advantage for ALCAR over placebo in mild cognitive impairment and mild Alzheimer's disease at 1.5–3g/day, apparent by 3 months and growing over time. A 2018 meta-analysis of 12 RCTs (Veronese et al., n=791) found a large reduction in depressive symptoms, comparable to antidepressants with fewer adverse effects, most clearly in older adults. A 2022 RCT in pre-frail older adults (3g/day) improved MMSE and walking distance. A 2020 critical review still calls its role in dementia "under debate". No healthy-young-adult trial was found.

ヒト効果マトリクス

Based on human clinical trials only. Animal and in-vitro data excluded.

効果エビデンス効果の大きさ研究数
Cognitive Function (MCI/Aging) strong
中
2
Mental Energy & Fatigue moderate
中
1
Mood & Depression moderate
大
1
Neuroprotection preliminary
小
2

Evidence key: Strong = multiple consistent RCTs · Moderate = smaller/fewer RCTs · Preliminary = early trials or small n · Mixed = conflicting results

実証された効果

  • Cognition in mild cognitive impairment and mild Alzheimer's (modest effect)
  • Fewer depressive symptoms, especially in older adults
  • Acetylcholine precursor

副作用と注意事項

  • Bipolar disorder: listed among agents associated with triggering manic or hypomanic episodes (case-report-level evidence) — avoid without psychiatric advice
  • ADHD: rated "not supported" by the 2022 WFSBP/CANMAT nutraceutical guidelines — do not use as an ADHD treatment
  • Fishy body odour at high doses (TMAO pathway)
  • GI discomfort
  • Insomnia if taken late
  • Rare: increased agitation in some individuals

摂取方法

Dosage1500–3000mg/day — the dose range of the positive trials; no positive trial we reviewed used less than 1,500mg/day
TimingMorning or early afternoon. ALCAR has mild stimulatory properties — avoid evening dosing to prevent sleep disruption.
With foodCan be taken with or without food. Absorption is not significantly affected by meals.
FormsCapsule or powder. ALCAR (acetyl form) is specifically required — plain L-Carnitine does not cross the BBB effectively. Look for "Acetyl-L-Carnitine" or "ALCAR" on the label, not "L-Carnitine" or "L-Carnitine L-Tartrate".

スタッキングの推奨

Acetyl-L-Carnitine (ALCAR)と相性の良い成分とその理由。

Alpha-GPC

ALCAR provides acetyl groups; Alpha-GPC provides choline. Together they support acetylcholine synthesis from both the acetyl and choline substrate sides.

Citicoline

Both support cholinergic function via different pathways. Citicoline provides CDP-choline for membrane repair; ALCAR provides mitochondrial energy and acetyl groups.

Lion's Mane

ALCAR protects existing neurons via mitochondrial support; Lion's Mane promotes new neuronal growth via NGF. Complementary maintenance + growth strategy.

よくある質問

ALCAR vs plain L-Carnitine — what is the difference?

The acetyl group on ALCAR allows it to cross the blood-brain barrier and donate acetyl groups for acetylcholine synthesis. Plain L-Carnitine primarily acts in muscles and peripheral tissue for fat metabolism. For brain benefits, ALCAR is required — plain L-Carnitine will not produce cognitive effects.

Does ALCAR raise TMAO levels?

Yes, carnitine (including ALCAR) is metabolised by gut bacteria into trimethylamine, which the liver converts to TMAO. Elevated TMAO is associated with cardiovascular risk in observational studies. The clinical significance at standard ALCAR supplement doses (1.5–3g/day) is debated. If you have existing cardiovascular concerns, discuss with your doctor.

Is ALCAR useful for young healthy adults?

Unproven. The evidence is for older adults with cognitive decline or depressive symptoms; our 2026 review found no trial in healthy young adults. It is not a first-line nootropic for healthy young people — L-theanine + caffeine has stronger acute evidence. It is also not supported for ADHD.

Can ALCAR help with brain fog?

Possibly. ALCAR supports mitochondrial energy production in neurons, which may address brain fog caused by metabolic insufficiency. Anecdotal reports are common but controlled evidence specifically for "brain fog" in healthy adults is limited. If brain fog persists, investigate underlying causes (sleep, thyroid, iron levels) rather than relying solely on supplements.

Acetyl-L-Carnitine (ALCAR) in Japan

Products in Japan

None of the stacks we have audited are listed in our catalogue in Japan yet.

Consumer Affairs Agency (FFC)

Prefecture guides

Regulatory note

本ページは教育目的の編集コンテンツであり、医学的助言を構成するものではありません。日本国内で販売される機能性表示食品（FFC）および特定保健用食品（FOSHU）は、消費者庁への届出または許可を必要とします。届出のない輸入品については、日本の薬機法（旧薬事法）の下で疾病治療を示唆する表現は規制されます。サプリメントを開始する前に、必ず資格のある医療専門家にご相談ください。This page is editorial and not medical advice. Foods with Function Claims (FFC) and Foods for Specified Health Uses (FOSHU) sold in Japan require notification or approval from the Consumer Affairs Agency. Imported products without notification cannot make disease-treatment claims under the Pharmaceuticals and Medical Devices (PMD) Act. Note: In July 2026, the Consumer Affairs Agency (CAA) opened a public comment period (Notice No. 235080088, closes 30 July 2026) on proposed revisions to permitted claim wording for FFC-notified ingredients including DHA, phosphatidylserine, and NMN; compliant claim language may require updating once the final Cabinet Office Order is published. Consult a qualified healthcare professional before starting any supplement.

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