Squalene (shark/olive) — The Antioxidant Lipid Precursor
Squalene is a natural lipid and cholesterol precursor found abundantly in shark liver oil and olive oil. It acts as a potent antioxidant and skin protectant, neutralizing free radicals and supporting cellular defenses against oxidative stress, though its direct impact on human longevity remains unproven.
Mechanism of Action
Squalene is a 30-carbon isoprenoid compound and a key intermediate metabolite in the synthesis of cholesterol and other sterols. It accumulates in the skin and liver, where it functions as a potent quencher of singlet oxygen, protecting lipid membranes from oxidative stress and UV-induced damage. Mechanistically, squalene has been shown to promote the dissociation of Keap1 from Nrf2, leading to the nuclear translocation of Nrf2 and the subsequent upregulation of endogenous antioxidant defenses. It also modulates inflammatory pathways by targeting pro- and anti-inflammatory mediators.
Human Trial Evidence
Human trials are limited primarily to dermatological outcomes. A 2009 trial found that high-dose squalene ingestion (13.5–27 g/day) increased type I procollagen and decreased UV-induced DNA damage in human skin in vivo, but was associated with transient loose stools. No published human longevity trials exist.
Dosing Protocol
13.5–27 g/day has been studied in human trials for skin photoaging, though lower doses (200–500 mg/day) are more common in commercial supplements. Often taken with meals to improve absorption. Long-term safety of high doses is unestablished.
Safety & Contraindications
Generally considered safe at typical supplement doses. High doses (e.g., >13 g/day) frequently cause transient loose stools or gastrointestinal distress. Ingestion of squalene capsules has rarely been associated with severe lipoid pneumonia due to aspiration. Caution is advised in individuals with lipid metabolism disorders, as squalene is a cholesterol precursor.