The health benefits of consuming olive oil are well-documented. For example, various studies have already shown that the regular use of extra virgin olive oil is beneficial for the bones because it stimulates the absorption of calcium and therefore bone strength. It also boosts the endocrine system, since it improves metabolic function. What's more, it aids circulation by helping to prevent the build-up of fatty matter in the blood vessels, a problem which can lead to heart attacks and strokes. Now, researchers from the University of Jaén have discovered that extra virgin olive oil facilitates the organism's defence against bacterial infections to a greater extent than fish oil, even when the body's defences are worn down. The researchers have demonstrated the effectiveness of the oil against bacteria such as E.coli and salmonella.

Fish oil has very effective anti-inflammatory action, and is useful for helping prevent arteriosclerosis, the build-up of fat in the arteries. However, this anti-inflammatory action reduces the body's defences can leave it prone to possible infections. On the other hand, this does not occur with extra virgin olive oil, which is also good for fighting cardiovascular disease, but does not reduce the body's immune system.

In order to reach this conclusion, the researchers fed groups of mice diets rich in either olive oil (extra virgin or organic), fish oil, sunflower oil or corn oil. After four weeks, they were administered drugs to weaken their immune systems. They were then inoculated with pathogenic bacteria. Finally, the survival time of the animals was compared.

The results showed that the survival rate of the mice that had been fed the olive oil-rich diet was far superior to that of the animals fed on fish oil. ''Now our task is to investigate the resistance animals have to other bacteria and to determine why they survive for longer and what the implications are.''

This investigation may prove to be a breakthrough in the fight against bacterial infections and the deaths they cause. According to the researchers, the people who are most susceptible to contracting bacterial infection are those who are undergoing prolonged anti-inflammatory treatment, insulin-dependent diabetics and the elderly.