High‐Fat Diet Intake Enhances Ultraviolet‐Induced Melanin Production in the Skin

The intake of a high-fat diet (HFD) increases the risk of metabolic diseases such as obesity and type 2 diabetes and has also been associated with age-related changes in various organs. However, its effects on the skin remain poorly understood. Ultraviolet (UV) exposure is a major environmental factor that induces skin pigmentation through enhanced melanogenesis. However, little is known about the effects of HFD intake on UV-induced skin pigmentation. This study investigated whether HFD intake modulates UV-induced melanogenesis. HRM-2 mice were fed either a standard diet or an HFD for 5 weeks. The melanin content in the dorsal skin of UV-exposed HFD-fed mice (UV + HFD group) was significantly greater than that in the dorsal skin of UV-exposed mice fed a standard diet (UV group). The mRNA levels of tyrosinase (Tyr), dopachrome tautomerase (Dct), and tyrosinase-related protein-1 (Tyrp1) were higher in the UV + HFD group than in the UV group. The protein expression of TYR and microphthalmia-associated transcription factor (MITF) was significantly greater in the UV + HFD group than in the UV group. HFD intake enhances the UV-induced upregulation of the expression of MITF and melanogenic enzymes, resulting in exacerbated skin pigmentation. These findings suggest that nutritional status may influence susceptibility to UV-induced pigmentation and that dietary modulation represents a potential strategy to control UV-induced hyperpigmentation.