Oral Intake of Linseed Oil Inhibits Skin Barrier Dysfunction in Obese Mice

Obesity is not only a risk factor for lifestyle-related diseases but also causes skin barrier dysfunction, which leads to a reduced quality of life due to dryness, itching, and scratching, and thus requires appropriate treatment. However, there are no studies on this issue. Therefore, this study aimed to examine whether oral intake of linseed oil is effective for skin barrier function in obesity and to confirm how the effect is demonstrated.

TSOD mice received either sterile distilled water (Control group) or linseed oil (Omega group), containing a high level of omega-3 fatty acids, including α-linolenic acid, orally for eight weeks. Mice were then irradiated with ultraviolet B (UVB) and three days later, transepidermal water loss (TEWL), which is the primary outcome of skin barrier function, was measured and gross skin appearance was observed. Hematoxylin and eosin (HE) staining and Ki-67 immunostaining were performed on skin samples. mRNA expression levels of the inflammatory markers Tnfα, Cox2, Mcp1, and Hmox1 were measured by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). We also performed fatty acid analysis of skin and erythrocytes by gas chromatography. Statistical analysis was performed using unpaired Student's t-test and Pearson's correlation analysis.

Compared with the Control group, the Omega group exhibited lower TEWL values and little skin erythema. Histological analysis revealed thinner epidermis and fewer Ki-67 positive cells. Additionally, in the Omega group, mRNA levels of four inflammation-related genes were lower, α-linolenic acid levels in both skin and erythrocytes were higher, and a lower n-6/n-3 ratio was observed. And α-linolenic acid levels in the skin were negatively correlated with the expression levels of inflammation-related genes.

Oral intake of linseed oil was found to inhibit skin barrier dysfunction in obesity. This effect was mediated by α-linolenic acid, a major component of linseed oil with anti-inflammatory properties, which was taken up by erythrocytes and supplied to the skin. Therefore, oral intake of linseed oil is expected to be a useful therapeutic method for skin barrier dysfunction in obesity.