The benefits of omega-6 on the skin

Consuming omega-6 can have beneficial effects on the skin, particularly by promoting skin healing. Rui CURI and his colleagues wanted to study the effects of oral ingestion of oleic acid (OLA), an omega-9, and linoleic acid (LNA), an omega-6, on wound healing in rats. 0.22 g per kg of body weight were administered for five days.

After seven days of healing, the results show a clear improvement in wound closure in the LNA group compared to the OLA group. Concurrently, the LNA group demonstrated an infiltration of inflammatory cells, primarily neutrophils and lymphocytes, and an increase in the production of H2O2, a reactive oxygen species. Subsequently, 24 hours after the injury, LNA reduced the number of inflammatory cells and the concentrations of IL-1, IL-6 and macrophage inflammatory protein-3 (MIP-3), as well as the activation of NF-kB. The inflammatory response thus decreased after this time. Concurrently, there was an increase in the production of H2O2, a reactive oxygen species, after consumption of omega-6.

Studies have shown that an increase in the content of reactive oxygen species can also signal the activation of Activator Protein 1 (AP-1). The activation of AP-1 is linked to the proliferation and differentiation of keratinocytes and fibroblasts, important cells that participate in the subsequent phase of wound repair. Later, the pro-inflammatory scenario appears to be deactivated, particularly the activation of NF-kB and the production of pro-inflammatory cytokines, although the activation of AP-1 persists. This early resolution of the inflammatory phase and the onset of the next phase (formation of granulation tissue) could explain the accelerated healing observed in this group.

No study has shown a specific effect of omega-6 consumption on the risk of developing skin cancer. However, experiments have been conducted on the action of omega-6 located in the plasma against tumour development. In a study led by Jolieke C. VAN DER POLS, researchers investigated the associations between baseline plasma concentrations of omega-3 and omega-6 fatty acids and basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) in 1,191 Australian adults, who were then followed up from 1997 to 2007.

Plasma omega-6 levels were inversely associated with BCC tumours, and more strongly in the subgroup that had already had skin cancer. Specifically, in this omega-6 subgroup, the linoleic and linolenic acids were inversely associated with the occurrence of BCC. Therefore, it can be hypothesised that omega-6, and potentially their oral intake, can act in one way or another against tumorigenesis.

Nevertheless, these remain hypotheses and the mechanisms involved have not yet been identified.

A significant body of research on the subject indicates a predominantly pro-inflammatory effect of a diet high in omega-6. However, other studies also suggest an anti-inflammatory activity. In particular, gamma-linolenic acid has been shown to have the ability to alleviate the symptoms and signs of atopic dermatitis, an inflammatory skin disease. The oral administration of oil rich in gamma-linolenic acid to patients with mild atopic dermatitis has been able to restore the skin barrier by reducing transepidermal water loss, thus resulting in more effective skin hydration.

One explanation could be the potential production of anti-inflammatory metabolites from omega-6. Indeed, gamma-linolenic acid contributes to the biosynthesis of omega-6, leading to the synthesis of anti-inflammatory metabolites (PGE1 and 15-HETRE). It is known that PGE1 and 15-HETrE have the ability to inhibit the production of pro-inflammatory eicosanoids, and thus alleviate associated symptoms.

Further studies are underway to clarify these results.

• CURI R. & al. Oral Administration of Oleic or Linoleic Acid Accelerates the Inflammatory Phase of Wound Healing. Journal of Investigative Dermatology (2012).

• VAN DER POLS J.C. & al. Plasma Omega-3 and Omega-6 Concentrations and Risk of Cutaneous Basal and Squamous Cell Carcinomas in Australian Adults. Cancer Epidemiology, Biomarkers & Prevention (2013).

• MOKOS Z.B. & al. Omega-3 versus omega-6 polyunsaturated fatty acids in the prevention and treatment of inflammatory skin diseases. International Journal of Molecular Sciences (2021).