High nitrate intake impairs liver functions and morphology in rats; protective effects of α-tocopherol

The aim of this study was to determine the effect of high dose nitrate ingested in drinking water, on liver enzymes and histopathology, liver weight/body weight (lw/bw) ratio, serum and liver malondialdehyde (MDA) levels and osmotic fragility in Sprague-Dawley rats. These parameters were compared on 40 rats divided into four groups; control animals (group A) drank filtered tap water containing maximum 10 mg/L nitrate while treatment groups drank 200 mg/L (group B), 400 mg/L (group C) and α-tocopherol plus 400 mg/L (group D) nitrate containing water ad libitum for 60 days. As a result, lw/bw ratio increased significantly (p < 0.05) among rats that consumed water with 400 mg/L nitrate. Osmotic fragility increased significantly in treatment groups (p < 0.05 versus control). Liver but not serum MDA levels increased in group C (p < 0.05 versus control). Group A showed normal hepatic lobular architecture and histology. After nitrate administration, there was hepatocellular degeneration with increased intercellular space of the liver cells in groups B and C. Liver MDA, osmotic fragility and liver histology have returned to nearly normal in group D. These findings show clearly that high nitrate ingestion can cause pathological changes in liver histology and functions. Moreover, α-tocopherol can prevent these effects, possibly through antioxidant properties.