What we eat: Food manufacturers have moved to exploit the popular view that you can eat yourself healthy by consuming foods that deliver assumed health benefits. These new "functional foods" may be the making of Ireland's already substantial food production sector.

Nutritionists, the food safety watchdog, and scientists working on new products all agree that functional foods are the way forward. All also urge caution, however, warning that while benefits to health can be proven for a small number of products, many others, including very popular brands, deliver nothing more than unnecessary calories.

"The functional food sector is a growing element of the food industry and one the Irish food industry is taking very seriously," states Teagasc Moorepark research scientist Dr Catherine Stanton.

Manufacturers recognise the opportunity to bring "added-value foods" to the market and are actively researching them. The customer, too, has become more aware of the potential as a result of intensive advertising campaigns. "The consumer is more aware of food and dietary issues and also nutrition and health promotion," Stanton believes.

Unfortunately there is a random element to some of the claims being made for functional foods and "probiotics", says University College Cork's professor of food microbiology, Prof Gerald Fitzgerald.

"You have a kind of wild west market. You are looking at an early phase where regulation isn't as tight as it is going to be," Fitzgerald says. "You have a number of foods that make spurious claims where scientific discipline was not really applied to the functionality of the particular product. That would have done some damage to the market, I believe."

Probiotic is the most commonly used term for these products. We may not understand what the term means, but many of us readily accept - often without a shred of scientific evidence - that it is a byword for health. Unfortunately, products making health claims often come at a premium price and may do nothing whatsoever for the person consuming them.

This is not say there is no evidence on behalf of functional foods. The inclusion in drinks and spreads of a cholesterol-reducing substance from plants known as sterols (or stanols) has been proven to reduce cholesterol by 10 to 14 per cent in many patients. "Plant sterols are beyond any doubt in terms of clinical efficacy," states Fitzgerald, who is also deputy director of UCC's Alimentary Pharmabiotic Centre.

Japanese and Finnish manufactures have developed milk products that can reduce blood pressure, a serious risk factor for cardiovascular disease. "There are clinical trials that show that some have enough effect to control inflammatory bowel disease," he adds.

"I think the evidence is growing there really is something there," says the professor of human nutrition in the University of Ulster Coleraine School of Biomedical Sciences, Prof Ian Rowland.

While you "have to be a bit careful" with the claims, some of these products are being used in a clinical setting and in properly controlled human trials to measure their value. "There is a lot of clinical use, although you wouldn't describe them as drugs," says Rowland.

He cites various trials which showed that some probiotic products could help children overcome common bowel upsets, such as diarrhoea caused by the rotavirus, more quickly.

"The problem is translating this into some kind of claim for a healthy adult."

There is also more and more evidence that certain milk-derived bacteria can have an influence on inflammatory bowel disease and, significantly, colon cancer.

"There are some quite nice clinical trials that show people with colitis have less relapsing," says Rowland, who studies probiotics and also "prebiotics". These are non-digestible carbohydrates that aid the growth of "good" bacteria in the gut. "We are working on cancer. There is a lot of evidence in models and animals that probiotics and prebiotics may have anti-cancer effects," Rowland says.

Stanton is also working on the anti-cancer effects of a substance found in milk and in beef fat called CLA, conjugated linoleic acid. It shows some clinical signs of being able to reduce the risk of breast cancer spreading to other parts of the body. She was involved in a trial where CLA was put into cheese and then consumed by hospital patients in Rome. These results were "very positive", she says.

"This whole area of personalised nutrition and bioactive elements in our food is moving forward."

Fitzgerald is very optimistic about the future of functional foods. "Where we are going is almost as broad as your imagination."

He believes the food industry has a very clear idea of where it wants to go. "Its business is not to treat diseases, its business is to improve health." People will eat these functional foods to enhance health rather than to seek cures. This requires considerable research to decide definitively whether a product has any value, however.

There is also the complexity of the human digestive system to be considered. "You are not dealing with a pure pharmaceutical, you are developing this as part of a complex food matrix," he says. We can't assume that additions to foods developed and tested in the lab will work the same once in this food matrix.

He also sees the potential of "cosmeceuticals", products developed by the cosmetic industry that work in a functional way with the skin and hair. Developments in this area are on the "very cutting edge" of research and still have a way to go.

Rowland also believes that scientists will try to genetically manipulate promising organisms. "I think there is going to be a lot of work on targeting these probiotics with genetic manipulation."