Squalene

Multiple reviews document squalene as a highly effective oxygen-scavenging agent that quenches singlet oxygen and prevents lipid peroxidation. In vitro studies confirm antioxidant activity, and squalene is a major lipid-soluble antioxidant in human skin (comprising ~13% of sebum). Mouse studies showed squalene increased paraoxonase 1 activity and decreased oxidative stress markers. Direct human supplementation trials for antioxidant endpoints are lacking.

Reviews identify squalene as an emollient, antioxidant, and skin hydrator with potential for treating seborrheic dermatitis, acne, psoriasis, and atopic dermatitis. One 90-day trial in women reported improved collagen levels, fewer facial wrinkles, and reduced skin redness and pigmentation from UV exposure. In vitro, squalane counteracted UVA-induced inhibition of collagen biosynthesis in human dermal fibroblasts. Evidence remains primarily preclinical.

In mouse models, oral squalene supplementation produced dose-dependent increases in cellular and non-specific immune functions and enhanced host resistance to tumor challenge. Squalene-based vaccine adjuvants (MF59) are well-validated for enhancing immune responses in humans, stimulating both antibody and CD8 T cell responses via RIPK3-dependent pathways. However, these immune adjuvant data are specific to injected formulations rather than oral supplements.

A 2020 systematic review identified 21 studies (3 human, 18 animal) on squalene and cardiovascular risk. In animal models, 15 of 18 studies reported positive effects on lipid profiles, potentially via HMG-CoA reductase inhibition similar to statins. However, only 1 of 3 human studies showed a positive effect, and the reviewers concluded evidence remains insufficient for definitive claims.