The research, published in Nutrition and Metabolism reports that rats fed on a diet containing olive oil were partially protected from liver damage after being exposed to a moderately toxic herbicide known to deplete antioxidants and cause oxidative stress.
“Olive oil is an integral ingredient in the Mediterranean diet. There is growing evidence that it may have great health benefits including the reduction in coronary heart disease risk, the prevention of some cancers and the modification of immune and inflammatory responses,” said Prof. Mohamed Hammami from the University of Monastir, Tunisia and King Saud University, Riyadh, Saudi Arabia.
“Here, we’ve shown that extra virgin olive oil and its extracts protect against oxidative damage of hepatic tissue,” he added.
Oxidative stress
In healthy people, the generation of reactive oxygen species generation (ROS) is counterbalanced by the action of antioxidant. However, oxidative damage caused by an imbalance in ROS and antioxidants is a major contributor to the development of many diseases including CVD, cancer and neurodegenerative disorders.
In experimental studies, olive oil and its phenolic compounds have shown strong antioxidant properties, with the authors noting growing evidence that it may have health benefits including the reduction in coronary heart disease risk, the prevention of some cancers and the modification of immune and inflammatory responses.
The new study explored the idea that, owing to its high content of natural antioxidants, olive oil could reduce oxidative damage in rats.
Because the liver is not only the main target for phenolic antioxidants once absorbed from the gut but is also the major place for phenolic metabolism, the researchers stated that studies investigating the effect of antioxidant dietary phenolics on the liver should be given priority.
They tested the effect of dietary supplementation of olive oil and its phenolic fractions (hydrophilic or lipophilic) on oxidative stress and liver fatty acid composition of rats treated with the oxidative stress inducing herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D).
Decreased damage
All rats given 2,4-D were reported to show signs of significant liver damage. However, extra virgin olive oil and intake of its hydrophilic fractions were observed to induce a significant increase in antioxidant enzyme activity and decreased markers of liver damage.
The lipophilic fraction supplemented to 2,4-D- treated rats was observed to not show any improvement in the liver oxidative status.
The authors detected a marked improvement in the hepatic fatty acid composition of rats supplemented with olive oil and both the hydrophilic and lipophilic fractions.
Protective effect
The researchers concluded the protective effects of olive oil against oxidative damage are mainly related to the antioxidant potential of its hydrophilic fraction.
“The hydrophilic fraction of olive oil seems to be the effective one in reducing toxin-induced oxidative stress, indicating that hydrophilic extract may exert a direct antioxidant effect on hepatic cells,” said Prof. Hammami.
“However, more detailed studies about the effect of antioxidant compounds separately and/or their interactions are necessary to substantiate these observations,” he added
Source: Nutrition & Metabolism
Published online ahead of print, doi:10.1186/1743-7075-7-80
“Effects of olive oil and its fractions on oxidative stress and the liver's fatty acid composition in 2,4-Dichlorophenoxyacetic acid- treated rats”
Authors: A. Nakbi, W. Tayeb, A. Grissa, M. Issaoui, S. Dabbou, I. Chargui,M. Ellouz, A. Miled, M. Hammami