The discovery explains how the fatty acid-sensing enzyme PanK2 tailors production of this key molecule, coenzyme A (CoA), to the cell's energy demands, according to Yong-Mei Zhang, Ph.D., a researcher in the Infectious Diseases department at St. Jude. Understanding PanK2 function is also important because mutations in this enzyme cause PanK-associated neurodegeneration (PKAN), she added. Zhang is senior author of the report that appears in the online pre-publication issue of Proceedings of the National Academy of Sciences.

The team demonstrated that PanK2 responds to increasing levels of fatty acids within mitochondria -- the bags of enzymes in the cell that extract energy from nutrients. The researchers also showed that CoA normally binds tightly to PanK2, shutting it down. When fatty acids accumulate in the cell, a molecule called carnitine shuttles them into the mitochondria. This combination of a fatty acid and carnitine liberates PanK2 from the bondage of CoA. Once free, PanK2 resumes its job of initiating production of more CoA, which is needed for the fatty acid breakdown.

"Our findings suggest that reducing the level of fat in the diet and taking carnitine supplements might help patients with PKAN cope with this debilitating disease," said Roberta Leonardi, Ph.D., a postdoctoral fellow in the Infectious Diseases department at St. Jude and first author of the article.

"We'd like to develop an animal model of this disease to determine whether reduced dietary fat and carnitine supplements offer hope in the treatment of PKAN in humans," said Suzanne Jackowski, Ph.D., a member of the Infectious Diseases department at St. Jude.

The other author is Charles Rock, Ph.D., who is also a member in the Infectious Diseases department of St. Jude.

This work was supported in part by the National Institutes of Health, a Cancer Center (CORE) Support Grant and ALSAC.

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The confidence to run this study came from a large body of existing evidence which has demonstrated the anti-cancer potential of watercress, including a laboratory study with human colon cancer cells, run by the same research group. Published in May 2006, the study showed for the first time that a watercress extract had beneficial effects on initiation', the DNA damage that triggers cancer cell development, proliferation' or uncontrolled growth of cancer cells, and metastasis', the spread of cancer cells. These are the three key stages of carcinogenesis, the process that results in cancer. Watercress extract was also shown to trigger cell death of cancerous calls - a process known as apoptosis.

UK TV presenter and survivor of bowel cancer Lynn Faulds Wood commented: "The research from the University of Ulster is very interesting - it's great to know there are simple things that people can do - like eating watercress - which could help them avoid getting cancers like bowel cancer in the future. It's great that the watercress farmers want to raise awareness of bowel cancer, the commonest cancer in Europe. Thousands of people die unnecessarily of bowel cancer every year - with exercise and a good diet, many of them could live."

Cultivated in pure spring water, watercress has been revered as a superfood down the centuries. Hippocrates, the father of medicine, is said to have located his first hospital close to a stream to ensure fresh watercress to help treat his patients. Greek soldiers were given it as a tonic before going into battle and the 16th Century herbalist Culpepper claimed it could cleanse the blood. It is brimming with more than 15 essential vitamins and minerals. Gram for gram, it contains more iron than spinach, more vitamin C than oranges and more calcium than milk.

Watercress is the UK's most historic salad leaf and in the 19th Century was a staple part of the working class diet, most often eaten for breakfast in a sandwich. If people were too poor to buy bread, then they ate it on its own, which is why it was sometimes known as "poor man's bread." Bunches were handheld and eaten ice-cream cone style - the first "on the go food."

After decades of being pushed to the side of the plate as nothing more than a decorative garnish, watercress is currently enjoying a renaissance, with sales increasing by 18 million a year to 55 million. Consumers and celebrities alike are re-discovering its distinctive peppery taste and its amazing nutritional benefits. - Liz Hurley has been known to drink seven cups of watercress soup a day!

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