Quick Comparison
| ALCAR | Shilajit | |
|---|---|---|
| Half-Life | 4-5 hours | 6-10 hours (fulvic acid components) |
| Typical Dosage | Standard: 500-2000 mg daily in 1-2 doses. For cognitive support: 1000-2000 mg daily. For neuropathy: 1500-3000 mg daily. Take in the morning — may be mildly stimulating. | Standard: 250-500 mg purified resin daily. PrimaVie is the most studied branded extract. Take in the morning with warm water or milk. Resin form preferred over powder for purity. Effects build over 2-4 weeks. Always buy from reputable sources — contamination with heavy metals is common in cheap products. |
| Administration | Oral (capsules, powder). Well-absorbed on an empty stomach. | Oral (purified resin, capsules). Dissolve resin in warm water. Take in the morning. |
| Research Papers | 9 papers | 10 papers |
| Categories |
Mechanism of Action
ALCAR
ALCAR crosses the blood-brain barrier via the organic cation transporter (OCTN2) more effectively than L-carnitine. In neurons, it is hydrolyzed by carnitine acetyltransferase to donate its acetyl group to coenzyme A, forming acetyl-CoA—which can then be used for acetylcholine synthesis via choline acetyltransferase, effectively providing raw material for the memory neurotransmitter. ALCAR also transports long-chain fatty acids across the inner mitochondrial membrane via the carnitine palmitoyltransferase system for beta-oxidation and ATP production. ALCAR activates nerve growth factor (NGF) signaling, possibly through modulation of NGF receptor (TrkA) expression or downstream MAPK/ERK pathways. It has antioxidant properties, reducing lipid peroxidation in mitochondrial membranes and scavenging free radicals. These mechanisms support cognitive function and neuroprotection.
Shilajit
Fulvic acid is the primary bioactive, acting as an electron shuttle that donates and accepts electrons — enhancing mitochondrial electron transport chain efficiency by facilitating electron transfer at Complex I and II, similar to CoQ10 but through a different (non-enzymatic) mechanism. DBPs (dibenzo-alpha-pyrones) protect CoQ10 from oxidation by scavenging radicals, extending its functional life in the reduced ubiquinol form. The combination increases ATP production in mitochondria. Fulvic acid also chelates minerals (iron, zinc, magnesium) via carboxyl and phenolic groups, forming soluble complexes that transport across cell membranes via divalent metal transporter 1 (DMT1) and other channels, improving bioavailability. It has direct antioxidant effects (scavenging ROS) and anti-inflammatory effects through inhibition of complement C3 activation and NF-kB.
Risks & Safety
ALCAR
Common
Nausea, fishy body odor, restlessness, gastrointestinal discomfort.
Serious
May increase agitation in Alzheimer's patients. TMAO production may be a cardiovascular concern with chronic high doses.
Rare
Seizures in susceptible individuals, increased thyroid activity.
Shilajit
Common
Mild GI discomfort, metallic taste.
Serious
Heavy metal contamination in unprocessed/cheap products (lead, arsenic, mercury). May increase iron absorption — caution with hemochromatosis. May lower blood pressure.
Rare
Allergic reaction, gout flare (increases uric acid in some people).
Full Profiles
ALCAR →
Acetyl-L-Carnitine is an acetylated form of L-Carnitine that crosses the blood-brain barrier more effectively than regular L-Carnitine. In the brain, it donates its acetyl group for acetylcholine synthesis and supports mitochondrial fatty acid oxidation for energy. Used clinically for age-related cognitive decline, depression, and diabetic neuropathy.
Shilajit →
A mineral-rich resinous substance that oozes from rocks in the Himalayas, formed over centuries from decomposed plant matter. Shilajit contains fulvic acid, dibenzo-alpha-pyrones (DBPs), and over 85 trace minerals. In Ayurveda, it is considered one of the most potent rejuvenation substances. Modern research confirms it enhances mitochondrial CoQ10 function, increases testosterone, and has nootropic effects through electron transport chain support.