Can we eat ourselves thin?

We all know obesity is on the increase. Almost one third of people living in the European Union (EU) are overweight and more than one in 10 is now obese, says the European Association for the Study of Obesity. And it looks as though the problem is only going to get worse, with 170m European adults and 154m US adults obese by 2008, according to market researcher Datamonitor.

While no one is seriously claiming that chewing on the right plant or adding the right compound to our orange juice is going to remove the need for portion control or exercise, there are results from more than a handful of clinical studies to support claims that some ingredients really could help people fight the flab.

First into the ring is conjugated linoleic acid (CLA), which Spanish food producer Central Lechera Asturiana has incorporated into its Naturlinea milk, orange juice, yoghurts and yoghurt drink product lines.

CLA doesn't promote weight loss as such. Instead it gradually reduces the proportion of fat in the body and builds up lean tissue. Naturally occurring in beef and dairy products, the transition to intensive farming and the resulting change in the diet fed to cattle means that it now occurs at far lower concentrations than it did a few decades ago. For example, the CLA in milk fat dropped from 2.81% in 1963 to just 1% in 1992.

Cognis is the largest supplier of the ingredient CLA, with its Tonalin weight-loss supplement brand accounting for around 70% of CLA sales. Clarinol is a rival product from Dutch firm Lipid Nutrition, a subsidiary of Loders Croklaan. Strong growth is expected now that CLA is expanding from the realm of 'magic pill' supplements into food.

A trial by Cognis found that Tonalin reduced the body fat of overweight but healthy individuals by up to 9% compared with a placebo (American Journal of Clinical Nutrition). Lipid Nutrition, meanwhile, cites no less than seven separate studies that all give similarly encouraging results in reducing fat, increasing lean tissue mass and reducing waistlines by dosing subjects with CLA.

CLA used in the industry is mainly derived from safflower oil and the mechanism behind how it works is still under investigation, but it is known to modify several enzymes involved in fat metabolisation and to affect the development of the cells where fat is deposited.

Both Tonalin and Clarinol achieved self-certified Generally Regarded as Safe (GRAS) status from the US Food and Drug Administration last year, so Lipid Nutrition and Cognis have been marketing them as food ingredients there ever since. But the situation in Europe is slightly more complicated, with an ongoing debate over whether CLA should be treated as a novel food ingredient or not.

Under EU legislation, a novel food or ingredient is one that was not commonly consumed in the EU prior to May 1997. But people were taking CLA as a supplement before that and it has always been present in, if not added to, the typical European diet.

"It's really confusing and frustrating for us and for the food companies," says John Kurstjens, marketing manager for Lipid Nutrition. "Food companies are naturally conservative, so everyone is waiting to see if anything happens [to affect the marketing of the Naturlinea products] in Spain."

Even so, he says there are more than 10 European companies, including some "really big" players, that are already formulating new foods containing Clarinol. He adds that we should expect to see products boasting CLA among their ingredients cropping up throughout the EU during 2005.

Big players in the slimming game don't come much bigger than Unilever, owner of the SlimFast brand. Unilever is preparing to bring its own secret weapon to the obesity fray in the shape of a succulent extract from South Africa known as Hoodia gordonii. In December last year, Unilever signed an exclusive global licensing deal with Phytopharm, a Cambridgeshire-based R&D company for the rights to the extract.

Unilever is not the first big backer of Hoodia. Drug company Pfizer previously held an exclusive licence from Phytopharm, but decided to hand the rights back when it closed its Natureceuticals group in 2003.

Unilever and Phytopharm will collaborate on a five-stage research programme. However, Unilever says that it will be at least three or four years before it's ready to introduce food products containing the Hoodia extract.

Hoodia is traditionally chewed by San tribesmen in southern Africa. It was originally used to prevent these people from feeling hungry when food was scarce. Now it seems it could also help with the opposite problem and stop people from tucking in with quite so much gusto.

In a small but well-publicised trial, Phytopharm locked up morbidly obese men and women for 15 days, with nothing to do but read, watch television and eat. Half the group were given Hoodia and half were given a placebo. At the end of the 15 days, the group on Hoodia had reduced their food intake by 1,000 calories a day. Double-blind animal studies since then have shown similarly encouraging results. The active compound in Hoodia is thought to be a molecule known as P57, which acts on the same part of the brain as glucose but is even more effective at convincing us that we're full.

A different succulent is the starting point for Neopuntia, the new weight management ingredient from French developer Bio Serae. In this case there is no doubt about its European status as a food ingredient, since the plant, Opuntia ficus-indica, has been eaten in Europe for many years.

Neopuntia received much publicity and food industry interest when it won a silver medal at the Health Ingredients Europe show in November 2004. "We made around 250 contacts in just three days," says Jeremy Jean-Louis, marketing manager for Bio Serae.

Fat binding

It may be derived from a cactus, but this ingredient is believed to work in an entirely different way from Hoodia extract. Neopuntia contains a combination of fibre and gelling agent that appears to bind to the fat found near the top of the stomach after a heavy meal. Bio Serae believes that this irreversible binding may prevent pancreatic lipase from splitting the fat into smaller units that could pass through the cellular wall of the small intestine and be stored. The fat instead passes on through the gut and exits the body.

It's a theory that appears to be borne out in trials. Researchers at TNO Nutrition and Food Research in The Netherlands tested the cactus powder with an artificial digestive system and found it absorbed 28.3% of the total fatty acids in a model meal. This was followed by a pilot clinical study in 2003, which found that the quantity of fat excreted compared with that ingested by volunteers increased on average by 27.4% when taking Neopuntia rather than a placebo.

Although the companies involved are keeping things under wraps for the moment, Jean-Louis says several food manufacturers are already developing products that contain Neopuntia. "Chocolate and candies with a functional application is an exciting [concept], because it allows people to take a product with Neopuntia inside after a meal," he says. Yoghurt drinks, pulpy fruit drinks, bread and tofu are also under investigation.

Jean-Louis believes that the chocolates and bread will hit the shelves within the year, although the other products could take up to three years to reach consumers.

More functional ingredients are arriving on the weight management scene all the time. January, for example, saw the publication in the American Journal of Clinical Nutrition of a new Japanese study showing that the catechins found in green tea appear to reduce weight, girth and subcutaneous fat if taken in sufficient concentration in tea. They even demonstrated the added bonus of a drop in cholesterol.

We are still in the early stages of what will surely be a major trend in functional weight control foods. After all, 44% of US adults and 29% of European adults are on a diet at any one time and Datamonitor predicts that we shall spend over $100bn (£530bn) on dieting by 2008. Whatever challenges obesity presents in terms of public health, figures like that also add up to a super-sized marketing opportunity. It's easy to see why everyone wants a slice of the pie. FM