Influence of dietary fish oil supplementation on DNA damage in peripheral blood lymphocytes of nine healthy dogs

BACKGROUND: Fish oil (FO) supplementation as a source of omega 3 fatty acids is associated with beneficial effects on health. However, high unsaturated fatty acid content in the diet could result in increased lipid peroxidation and damage to proteins, lipids and DNA. We evaluated the effect of dietary FO supplementation on DNA damage in peripheral blood lymphocytes of dogs. Additionally, we determined the effect of FO supplementation on lipid peroxidation and lipid profile of these dogs. METHODS: Healthy male dogs (n = 9) were randomly assigned to one of two diets during 90 days: control (CG, n = 4), based on a commercial food, and FO (FOG, n = 5), the same food supplemented with 1000 mg FO. Blood samples were collected on days −1, 30, 60 and 90. DNA damage was assessed with the comet assay, and the damage index was obtained. Malondialdehyde (MDA) levels were determined as an indicator of lipid peroxidation. Lipid profile determination included serum triglyceride, cholesterol, low‐density lipoprotein and high‐density lipoprotein levels (HDL). RESULTS: Damage index values (arbitrary units) were lower in FOG on day 30 (CG, 13.7 ± 2.5; FOG, 6.5 ± 2.5), 60 (CG, 14.7 ± 2.5; FOG, 3.5 ± 2.5) and 90 (CG, 15.5 ± 2.5; FOG, 3.0 ± 2.5) compared with CG (treatment × time interaction, p < 0.01). Serum MDA and HDL concentrations were lower in FOG compared with CG on day 60 and 90 (treatment × time interaction, p < 0.05). CONCLUSION: These findings suggest that dietary FO supplementation did not induce DNA damage in peripheral blood lymphocytes of healthy dogs, but rather reduced it.