L-Carnitine

Effects and Benefits

Core Identification

Common Names:
- L-Carnitine
- Carnitine
- Acetyl-L-Carnitine (ALCAR, ALC)
- Propionyl-L-Carnitine (PLC)
- Levocarnitine

Latin Name: N/A (amino acid compound)

Category: Amino Acid

Uses

Traditional Uses

• Not traditionally used as a supplement; recognized medically in the 20th century
• Dietary sources (red meat, lamb, dairy) consumed historically for energy and vitality

Modern Uses

• Cardiovascular Health - Supports heart muscle energy production and circulation | Research quality: Moderate
• Key findings: In a study of 44 men with angina, 23% became free of exercise-induced angina after four weeks of supplementation vs. 9% on placebo. Helps neutralize free fatty acid buildup in oxygen-deprived heart cells. Raises HDL cholesterol while lowering total cholesterol and triglycerides.

• Source citations: Brewer, TDT Encyclopedia of Vitamins; Balch, Prescription for Herbal Healing

• Intermittent Claudication - Improves walking distance in peripheral artery disease | Research quality: Moderate

• Key findings: 2g carnitine taken twice daily increased pain-free walking distance by 75% after three weeks due to improved energy metabolism within muscle cells.

• Source citations: Brewer, TDT Encyclopedia of Vitamins

• Male Fertility - Enhances sperm quality and motility | Research quality: Moderate

• Key findings: Multiple clinical trials show L-Carnitine improves sperm count, motility, and normal sperm morphology. In one study, 100 men with low fertility treated with 3g/day showed statistically significant increases in total sperm count and vigorous swimming ability.

• Source citations: Moyad, The Supplement Handbook; Moline, Doctors Book of Natural Health Remedies

• Energy Production and Fatigue - Increases cellular energy and reduces fatigue | Research quality: Moderate

• Key findings: When 18 patients with chronic fatigue syndrome were given 1g carnitine three times daily, 12 significantly improved within 4-8 weeks. A placebo-controlled study in elderly adults found carnitine supplementation increased muscle mass, decreased fat, and improved cognitive function.

• Source citations: Brewer, TDT Encyclopedia of Vitamins; Moline, Doctors Book of Natural Health Remedies

• Cognitive Function (Acetyl-L-Carnitine form) - Supports brain energy and neuroprotection | Research quality: Moderate

• Key findings: Acetyl-L-Carnitine crosses the blood-brain barrier, increasing energy production in brain cells. Has neuroprotective benefits, helps increase neurotransmitters, and protects brain cells from stress effects. Called a "mind booster" by integrative physicians.

• Source citations: Colbert, Reversing Diabetes; Moline, Doctors Book of Natural Health Remedies; Lust, The Natural Remedy Bible

• Athletic Performance - May improve exercise capacity and oxygen uptake | Research quality: Preliminary (mixed)

• Key findings: 2g carnitine before exercise increased maximum oxygen uptake and muscle contraction efficiency at high intensity. Marathon runners taking 2g/day for six weeks showed 5.7% improvement in peak treadmill running speed. However, other studies have not replicated these benefits.
• Source citations: Brewer, TDT Encyclopedia of Vitamins; Moline, Doctors Book of Natural Health Remedies

Active Compounds

Primary Active Ingredients:
- L-Carnitine (base form) - Transports long-chain fatty acids into mitochondria for energy production
- Acetyl-L-Carnitine - Crosses blood-brain barrier; supports cognitive function and neurotransmitter production
- Propionyl-L-Carnitine - May be particularly beneficial for cardiovascular and peripheral circulation

Dosage Information

Standard Dosage:
- Form: Capsule or powder
- Amount: 250 mg–1 g per day
- Frequency: Once or twice daily

Therapeutic Dosage:
- Form: Capsule or powder
- Amount: 2,000–3,000 mg per day (divided doses)
- Purpose: Male fertility, chronic fatigue, cardiovascular support
- Duration: 4 weeks to several months for clinical effects

Maximum Safe Dosage:
- Daily maximum: 4 g (4,000 mg)
- Warning threshold: Diarrhea commonly occurs above 4 g/day; fishy body odor may develop at high doses

Bioavailability Notes:
- Humans synthesize relatively little carnitine, so supplementation may benefit those with higher needs
- Obese and elderly individuals typically have lower carnitine levels
- Dietary carnitine is well-absorbed; red meat (especially lamb and beef) provides the highest amounts

How to Take It

Timing:
- Best taken in the morning and early afternoon (before 3:00 PM)
- Can be taken on an empty stomach for optimal absorption
- Taking later in the day may impair sleep due to energy-enhancing effects

Synergies - What It Works Well With

Complementary Supplements:
1. Coenzyme Q10 (CoQ10) - Both support mitochondrial energy production | Synergistic effect on cellular energy and heart health
2. Alpha-Lipoic Acid - Protects mitochondria from oxidative damage | Combined effect enhances energy production and antioxidant protection
3. PQQ (Pyrroloquinoline Quinone) - Stimulates growth of new mitochondria | Together with carnitine, maximizes mitochondrial function and energy
4. Glutathione-Boosting Supplements (NAC) - Quenches free radicals in mitochondria | Combined effect protects mitochondria and increases ATP production

Avoidance - What NOT to Combine With

Supplement Interactions:
1. None specifically noted

Drug Interactions:
1. Thyroid Hormone Medications - Carnitine may interfere with thyroid hormone activity and may exacerbate hypothyroidism | Potential consequence: Reduced effectiveness of thyroid medication | Severity level: Moderate
2. Anticonvulsants (Valproic Acid, Carbamazepine, Phenytoin) - These medications can cause dramatic reductions in blood carnitine levels | Note: Supplementation may actually be beneficial to counteract depletion; consult physician | Severity level: Moderate (interaction may warrant supplementation)
3. AZT (Zidovudine) - AZT depletes carnitine in muscles | Note: Supplementation (up to 6g/day) may help restore carnitine levels | Severity level: Moderate (supplementation may be beneficial)

Food Interactions:
- None specifically noted

Safety Information

Contraindications:
- Hypothyroidism (may worsen condition or interfere with thyroid medication)
- Individuals on thyroid hormone replacement therapy should consult physician before use

Side Effects:
- Common: Nausea, vomiting, abdominal cramping, diarrhea (especially above 4g/day)
- Common at high doses: Fishy body odor
- Rare: Neurologic concerns such as peripheral neuropathy at very high doses

Long-Term Use:
- Generally considered safe for extended use at recommended doses
- Higher doses (2-3g/day) are practical for short-term therapeutic use but may not be sustainable long-term
- Monitoring recommendations: Watch for thyroid function changes if taking thyroid medication

Special Precautions:
- Take before 3:00 PM to avoid sleep disturbance
- Consult physician if pregnant or nursing
- Those with kidney disease should consult healthcare provider before supplementing

Primary Uses At-a-Glance

Primary: Heart and cardiovascular support, energy and fatigue, male fertility, cognitive function (acetyl form)

Secondary: Athletic performance, chronic fatigue syndrome, intermittent claudication, weight management support

Sources

Local Library:
- Brewer, Sarah - TDT Encyclopedia of Vitamins
- Moyad, Mark - The Supplement Handbook
- Colbert, Don - Reversing Diabetes
- Moline, Peg - The Doctors Book of Natural Health Remedies
- Balch, Phyllis - Prescription for Herbal Healing
- Gaby, Alan R. - A-Z Guide to Drug-Herb-Vitamin Interactions 2nd Ed
- Mars, Brigitte - The Home Reference to Holistic Health and Healing
- Gladstar, Rosemary - Herbal Recipes for Vibrant Health
- Lust, John - The Natural Remedy Bible
- Buhner, Stephen Harrod - Herbal Antivirals

General Knowledge:
- Clinical research and studies cited in source texts