The effect of tomato juice supplementation on biomarkers and gene expression related to lipid metabolism in rats with induced hepatic steatosis.

Purpose: Tomato products are a dietary source of natural antioxidants, especially lycopene, which accumulates in the liver, where it exerts biological effects. Taking into consideration this fact, the aim of the present study was to ascertain the effect of tomato consumption on biomarkers and gene expression related to lipid metabolism in rats with induced steatosis.

Methods: Adult male Sprague-Dawley rats (8 weeks old) were randomly grouped (n = 6 rats/group) in four experimental groups: NA (normal diet and water), NL (normal diet and tomato juice), HA (high fat diet and water) and HL (high fat diet and tomato juice). After 7 weeks, rats were euthanized, and plasma, urine, feces and liver were sampled to analyze the biomarkers related to lipid metabolism, inflammation and oxidative stress.

Results: The H diet induced steatosis (grade II) in the HA and HL groups, which was confirmed by the levels of alanine aminotransferase and aspartate aminotransferase, histological examination and the presence of dyslipidemia. The intake of tomato juice led to an accumulation of all-E and Z-lycopene and its metabolites in the livers of these animals; levels were higher in HL than in NL, apparently due to higher absorption (63.07 vs. 44.45%). A significant improvement in the plasma level of high-density lipoprotein was observed in the HL group compared with HA animals, as was an alleviation of oxidative stress through reduction of isoprostanes in the urine. In relation to fatty acid gene expression, an overexpression of several genes related to fatty acid transport, lipid hydrolysis and mitochondrial and peroxisomal β-fatty acid oxidation was observed in the HL group.

Conclusions: The consumption of tomato juice and tomato products reduced hallmarks of steatosis, plasmatic triglycerides and very low-density lipoproteins, and increased lipid metabolism by inducing an overexpression of genes involved in more efficient fatty acid oxidation.