Fat pressed from the exotic fruit could be a potent weapon against conditions such as heart disease and cancer, it is claimed.

Avocado oil is similar in composition to olive oil, consumption of which is associated with unusually low levels of chronic disease in some Mediterranean countries.

New research conducted in Mexico, the world's largest avocado producer, has demonstrated its power to combat destructive rogue oxygen molecules.

These unstable ``free radicals'' wreak havoc in the body, triggering chain reactions that destroy cell membranes, proteins and even DNA.

The phenomenon is one of the prime drivers of ageing and is believed to play a major role in damage to arteries and cancer.

Oxygen-free radicals, or ``reactive oxygen species'', are natural waste products of metabolism but may be generated in greater numbers due to factors such as pollution, tobacco smoke and radiation.

One hotspot for free radicals is mitochondria, rod-like bodies in cells that act as energy powerplants.

Many ``antioxidant'' chemicals in vegetables and fruits such as carrots and tomatoes are known to neutralise free radicals. But according to Christopher Cortes-Rojo, who led the new research on avocado oil, they cannot reach the free radicals in mitochondria.

``The problem is that the antioxidants in those substances are unable to enter mitochondria,'' said Mr Cortes-Rojo, of the University Michoacana de San Nicolas de Hidalgo in Morelia, Mexico.

``So free radicals go on damaging mitochondria, causing energy production to stop and the cell to collapse and die. An analogy would be that, during an oil spill, if we cleaned only the spilled oil instead of fixing the perforation where oil is escaping, then the oil would go on spilling, and fish would die anyway.''

Experiments on yeast showed that avocado oil was effective against mitochondrial free radicals. Yeast cells treated with the oil were able to survive high exposure to iron, which triggers production of huge numbers of the molecules.

``These results could be attributed to the fact that avocado oil caused accelerated respiration in mitochondria, which indicates that the use of nutrients for producing energy for cell functions remains effective even in cells attacked by free radicals,'' Mr Cortes-Rojo said.

The findings were presented at the annual meeting of the American Society for Biochemistry and Molecular Biology in San Diego, California.

Previous research conducted at Morelia General Hospital had shown that avocado lowers blood levels of cholesterol, and certain fats linked to diabetes.

``Our results are promising because they indicate that avocado consumption could improve the health status of diabetic and other patients through an additional mechanism to the improvement of blood lipids (fats),'' Mr Cortes-Rojo said.

``In some Mediterranean countries, low or almost no appearance of these kinds of diseases has been associated with the high olive oil consumption. Olive oil has a fat composition similar to that found in avocado oil. Therefore, avocado oil could eventually be referred to as the olive oil of the Americas.''