I started writing this four days before the deadline for my wife's MSc dissertation. She was working against the clock to pull together and polish 15,000 words of terrifyingly complex analysis of trends in social policy on immigrants. So I gave her some chocolate. Not just any chocolate, mind, but GABA-enriched anti-stress chocolate.

GABA chocolate is only on sale in Japan. On the packet it says (in Japanese) 'Mental Balance Chocolate. For your struggle in a stressful society'. The confectionery company Glico launched GABA in 2004 and now sells US$40 million worth of the little Malteser-style chocolates every year, largely to Japanese businessmen. Takashi Komentani, a senior scientist with Glico, told me he gives GABA to his wife, too. 'She is an irritated person,' he said. 'So she eats it when I come home late and don't stop working.'

Useful stuff: I was well pleased when Dr Komentani slipped me a couple of packets. He had just completed a highly technical presentation on GABA to 100 or so food-industry scientists and marketing executives at the annual Food Technology and Innovation Forum in Dublin; I wondered if he'd had any GABA before making his speech. 'I looked nervous, didn't I?' he apologised. 'My English is bad. But I just arrived on the plane from Japan and to my regret, I was too tired to remember to eat some GABA.'

The presentation was great, I assured him. And it was. Dr Komentani told how he and his colleagues had found that gamma-amino butyric acid - GABA - a neurotransmitter that naturally occurs in the human brain, had calmed beagles, post-menopausal women and students undergoing intelligence tests. But the clincher was an experiment where they took 12 people with acrophobia - fear of heights - to Japan's highest footbridge. Dr Komentani and his colleagues gave half of them water containing 500mg of GABA (the equivalent of three-and-a-half packets of the chocolate). The other half got plain water to drink.

Then - in a scene straight out of late-night TV - they made them walk across the 300-metre long bridge. Saliva samples were taken from the poor acrophobics at various stages of the crossing, and their levels of immunoglobin and other stress bio-markers measured. The GABA-fed walkers showed clear reductions in stress levels. And so the Dublin lecture room buzzed.

GABA has been a huge hit in Japan since the launch in 2004. There are two reasons for its success - and both have significance for consumers in Europe. One lies in the fact that, in a country where chocolate is traditionally food for girls, this 'scientific' sweet has at last brought men into the market - just as probiotic yoghurts are attracting male consumers in Europe. Secondly - and much more importantly - it shows where the 'functional food' market could be going. Japan has blazed the way in food technology for much of the past century; the Japanese invented MSG and taste- enhancement, and they've already taken on the notion of functional food far beyond the West.

Superfoods, as they are known, are the fastest growing area in high-tech food research, not least because the Japanese market has shown what astonishing potential for profit there is. The market for fortified and functional food is most mature there, and was worth (according to Euromonitor) £8.2 billion last year. In the UK the business is newer, but has doubled in four years, to £2.7 billion. This is much more than the other great food boom of this decade, organic, whose amazing rise may now be levelling off, and whose sales were £1.9 billion last year in this country.

'Functional food is food you proactively eat to bring about specific lifestyle or healthful effects,' explained Peter Wennstrom, an industry analyst at the Dublin conference. 'And so the wet dream of all these people' - he gestured at the several hundred delegates from the big food companies, marketing consultancies and bio-tech laboratories - 'is a food that is massively processed, to add value, with obvious and provable health benefits, but that can be called "natural".' For today's worrying and confused food shoppers, the last point is perhaps the most important of all.

Dublin's Burlington Hotel has the sexy buzz that comes with conversation about very big money. The PowerPoint presentations in the conference rooms and workshops show graphs that all seem to point upwards, like the slopes of fantastical mountains. The rise in food shoppers' concern about health looks nearly vertical, the US$170 billion 'better for you' market will be up another 20 per cent by 2011, the 'naturally healthy' will rise to US$180 billion. The proportion of the public now buying foods 'usually or always with healthfulness in mind' is now 58 per cent in the UK and 72 per cent in the States.

And so, content with these figures - no one here is going to be out of a job - we go off to listen to the industry lecturing itself: 'How to make the health trends work for your brand'; 'Harnessing scientific studies to retarget health-conscious consumers' (this from Hershey, the US confectionery giant) and 'Understanding and targeting the allergy-free market'.

It seemed pretty cynical. The rooms were filled with scientists and salespeople from GlaxoSmithKline, Coca-Cola, Nestlé, General Mills, Unilever, Tate & Lyle, Cadbury, Mars, Tesco, Kellogg's and Allied Bakeries - all of them companies planning to make greater profits out of an increasingly nervous public's health concerns. The irony is that, in many cases, it was these companies' products, sugar- and fat-laden, massively processed and brilliantly marketed, that started those health fears in the first place.

'It is not fair to say that these companies are driving the health scares for profit,' says Wennstorm, whose own organisation, Health Focus International, analyses consumers and health trends for clients like PepsiCo and Tetrapak. 'But they are certainly exploiting consumers' frustrations. "Eating for health" is the biggest growth area in this market - and companies here are looking forward to a world where 100 per cent of consumer food spending is focused on the belief that you can go to the supermarket and buy health and wellbeing.'

For the superfood product developers, there are four areas of intense interest, some of which overlap. They are beauty, health, energy and brain function. Food and drink products to actively alter all of them are now with us, or imminent.

The most basic area of activity - and currently the busiest - are the More and Less products - food, drinks and snacks with vitamins or other nutrients added, and with calories raised or lowered, with a promise to make you more healthy, more energetic or more attractive.

They've been around since the 1990s, or before, and the technology is rarely new. Most of them are concerned with either lowering or raising 'energy density' levels, the calories from fats or sugar that will either give you energy or make you heavier, depending on how you use them. The charge of the 'lite' brigade has now gone so far that some analysts say it's over - the word will soon be meaningless because everything will be lite.

Michele Kellerhals, a senior scientist with Coca-Cola, told me that the vast drinks company, with 140 brands in Europe, now launches more 'diet drinks' than regular ones. Coke Zero - no calories - has been the most recent, and huge, success. 'The number of calories sold by Coca-Cola has dropped 14 per cent this decade, while our sales volume has risen healthily,' said Kellerhals. 'The truth is that the consumer wants beverages that cater for a healthy and active lifestyle.'

The truth is in fact somewhat more complex, and more interesting. The consumer actually wants to buy health and beauty while remaining on the sofa: our lifestyle is less active than it has ever been. Also, the consumer is prepared to pay the same, or more, for less, in terms of energy. These conundrums are exciting a novelty-obsessed industry. That's why Coca-Cola, a company once famous for employing virtually no scientists but armies of marketing guys, is currently carrying out 20 clinical trials on new health beverages, targeting hydration, heart health, bone health and beauty.

And the marketing methods in More and Less products are becoming increasingly sophisticated. Danone, the first brand to specialise in dairy products sold entirely on their health benefits, this year launched Essensis, a yoghurt drink with antioxidants and Vitamin E 'to nourish your skin from within'. Danone also owns Evian, another brand that's peddling the idea that you can drink yourself beautiful.

But where the science gets more intriguing - and scary - is in the world of fat. After 50 years or so in which the food and health industries have targeted the diet-conscious or overweight consumer with promises that their food is changed to contain less fat (while retaining its taste), the tables are now being turned. The new foods will change the consumer, from within.

In this field the buzzword among the scientists is 'satiety products' - food additives that make you think you've eaten more than you have, and thus work to control and diminish appetite. Kristina Williams, vice president of the Canadian company Natraceutical, a major player in this area, explains how her product, Viscofibre, acts to trick your mind to stop you eating. 'Firstly, in the stomach it will form a soft gel which will expand and give you the physical sensation of fullness. Because of its viscosity it will take longer to leave the stomach - so you will feel full for longer. Secondly, it changes your glycaemic response, slowing the uptake of sugar into the bloodstream - so it takes your body longer to absorb the sugar in the food. And thirdly when the food gets to your gut, it will affect two specific gut hormones, which carry messages to your brain that tell it whether or not you have eaten enough.'

Satiety additives are either complex oil emulsions which, undigested until they reach the lower gut, send a message from there to the brain to say 'appetite satisfied'. You can see these in slimming products like Fabuless, or SlimThru, in the UK. Or there are the liquids or powders that become unabsorbable fibres or gels in the stomach, and are ultimately excreted. They are now going into biscuits and drinks, into soups and cereals.

'The beauty of the technology is,' as one fibre salesman put it to me, 'you can market the new product as having extra fibre in it. "Fibre" is a good word, with consumers.' Coca-Cola has just used this technology to launch a version of its down-market juice Minute Maid as 'Breakfast-on-the-Go', a smoothie with 'a filling blend of fruits and fibre'. Will we see Coca-Cola with added fibre? I asked Michele Kellerhals. He wouldn't speculate, but there is on the company drawing board a very exciting new water 'with all the nutrients you need, from vitamin A to zinc. Think of it as a drinkable Swiss Army knife'.

The British sugar company Tate & Lyle is the sort of business you would think was going rapidly down the plughole, in this post-Sugar Age. But no, this ancient industry, whose exploitation of innovative technology goes back to the slave trade, has a lot of new products, including a sugar-free sweetener - made from sugar. And in Dublin the company was proudly launching Promitor, another version of the miracle fibre. This one is made from corn syrup, the source of most sugar products today. Tate & Lyle's reps would not talk to me - but I did get in to hear their director of health and nutritional sciences, Dr Sandra Einerhand, pitch the new product.

She ran through the benefits - fibre probably aids digestion and promotes a healthy gut, most Europeans don't eat enough of it, and she expects that Promitor, like the other new fibres, will induce a sense of satiation. Consumers like fibre - they believe it 'keeps you regular'. Because it's tasteless, Tate & Lyle are pushing Promitor for use in anything from ice cream and biscuits to soup and soft drinks. One of Promitor's greatest advantages is that because it is made from refined corn syrup, it is not a 'novel food' - and so it avoids the five-year queue for approval through the massively inefficient European Commission regulatory system that polices new products.

What amazed me - and some others in the room - was Einerhand's view of how the labelling would work. 'Promitor is consumer-friendly,' she said: it could be labelled as 'soluble gluco fibre' or 'glucose syrup'. I asked her whether a tasteless, colourless liquid designed to turn to indigestible fibre in your stomach and induce a feeling of satiation could honestly be called 'syrup' on the label. How could the average consumer possibly understand what it really is? 'We're just saying what's possible under current European regulation,' she replied.

And there is a hot topic. In July this year the European Commission at last issued a long-promised new directive on nutrition and health claims. It is both more stringent, and more vague than the national laws it is replacing, and thus the source of much frustration. Paraphrasing hard, the new directive states that nutrition and health claims must be backed by generally accepted scientific evidence; that the nutrient must be there in a significant quantity and produce the effect claimed; the quantities must be reasonable to produce the effect, and, perhaps most importantly, the average consumer must be expected to understand the beneficial effects as expressed in the claim. This list gives a pretty clear idea of the sort of bad practices that have held sway in the past.

Governments and the industry are still drawing up lists of health and nutrition claims for the European Food Standards Agency - an obscure Madrid-based body we are going to hear a lot more of - to assess permissible statements. But clearly hyperbolic claims, like Kellogg's 'Detox in a Box' for All-Bran cereal (which has now been dropped) will be out. When the new regulation finally filters through to labels from next year, phrases like 'healthy' or 'good for you' won't be permissible without specific scientific backing.

Dr David Mela, a senior scientist in weight control and behaviour nutrition at Unilever, told me he welcomes the new regulations, which he thinks are badly needed. What worries him, though, is a lack of capacity for enforcement. Unilever would indeed benefit from better regulation, and more consumer trust: it has invested heavily in the satiety science, with high hopes for a product called alginate which 'slows gastric emptying'. This is patented and under consideration for Unilever's internationally successful SlimFast range.

Mela agrees that much of the science is now beyond the understanding of ordinary consumers: And indeed, if you look at SlimFast's website looking for any information on how their products actually work, in physiological terms, you'll be disappointed. Mela told me it will be up to industry, overseen by government, to regulate itself. And he is confident that can happen.

But in his presentation Dr Mela was damning about some of the science he and his colleagues see used to promote functional foods. 'We see the positive results being used, but not the negative ones. We see a different product being marketed from the one that was tested.' Other common problems are results based only on laboratory tests, not real life ones, or products that only contain fractional amounts of the substance tested. 'Market hype commonly precedes or grossly outweighs evidence,' he stated.

But when I asked him why, on this evidence, the food industry should be trusted at all, Dr Mela said he blamed the scientists, not the corporations. 'There are academics doing the research who are under enormous pressure for their own careers to bring out positive research, pressure to produce what they think will impress the scientists.' As Peter Wennstrom says, 'Scientists are paid by people who want there to be a link between chocolate and health - so they'd better find it. And the public relations operation is directly connected to the scientists, because it's the best marketing tool we have today.'

Clearly there is immense pressure - from shareholders and the sales department to get the new products onto the market. Does that affect the science and the testing? Henk Zwier is head of business development with Lipid Nutrition, a Dutch bio-tech firm that has a stall at the conference promoting various satiety-related products. He was excited that one of them, PinnoThin, an extract of Korean pine nuts, is about to get its first commercial outing, launching in Naturally Gorgeous smoothies in the UK the following week.

PinnoThin - which has won several awards as an innovative health ingredient - is another of the products that exploits the fact that if you introduce fatty oils to the lower gut (by ensuring they're not digested in the stomach) a signal will be sent to the brain saying you've eaten enough. Does it work? Henk is an honest man: 'There's reason to believe that our product has an effect. The research is still going on to substantiate the claim, and we're launching with that research still going on. Dr Mela is right: claims generally in this field are in a grey area; I don't want to be rude about rivals, but ...' and he waves around the stands in the Dublin hall ' ...there's a lot of products here that are wishful thinking.' For Henk, the fact that his product was safe, is the main thing.

Naturally Gorgeous launched at the end of November and they kindly sent me some of their 'Keeping you fuller for longer' smoothies. I was interested to see how Henk's careful statements in Dublin translated into marketing-speak on their zippy website, all shocking pink and breathless. Click on 'Our new sexy ingredient' and you get 'Naturally Gorgeous drinks contain a natural extract of pine nuts which is rich in the type of essential fats that help to take away the need to be naughty'. PinnoThin, it went on, 'appears to help the drinks keep you feeling fuller for longer...' and further down 'A 250ml serving is perfect to keep you feeling fuller for longer'. Again, there was no explanation of how it actually worked.

The need to be naughty? It sounds like something you put in squaddies' tea. After drinking a tumbler of ruby orange and strawberry Naturally Gorgeous, I felt neither naughty nor full but just a little bit sick. My wife thought it tasted like coughsyrup, and two hours after breakfast she was making more toast.

The important word in Naturally Drinks' blurb is, of course, that strategic one, 'appears'. We're going to see a lot more of such careful approximation. The new EU regulation regime, says Peter Wennstrom, means that manufacturers will be pushed away from making absolute claims for their products. 'It will be the soft claims - "may reduce cholesterol", "might freshen up your skin". But I think that could result in less comprehension - and less trust - among the consumers.' Especially, you feel, since, as the Naturally Drinks website shows, this science is well beyond the patience or comprehension of the average smoothie-buyer. You also wonder if the word 'natural' still has any useful meaning at all.

Wennstrom takes a view that runs in opposition to the industry's basic innovate-or-die philosophy. He thinks that the most significant emerging force in food branding is actually the consumer's desire for the unprocessed and the natural. This is the 'less-is-more consumer', typified by those who buy the Innocent brand of juices and smoothies. And it is these products that command the highest prices.

'This industry, much of which is driven by venture capital, will always be focused on finding new products. That's its raison d'être. Why do you think the dairy industry led in functional foods? Because cows always go on producing milk, and you have to find new ways to sell it. That's an analogy for the whole of the food industry.

'The problem, though, is that consumers may well be getting bored of this ceaseless innovation. They don't always want to buy new: instead, they want to buy change. They can see the consequences of consumption, they're less interested in the differences between products, they're aware of the ecological footprint and the ethical behaviour of the company behind the product. What they want is the story of a food and its journey, and for a fitting story they will pay a premium. And that premium goes to the brand with the best story - not the best science.'

So what of the story of brain food and anti-stress chocolate? I met Dr Sunil Kochhar, a scientist with Nestlé, who has spent a lot of time examining exactly what it is that chocolate does to our brains. He is now close to producing something that he won't quite talk about. The gossip in Dublin is that what Kochhar has up his sleeve is a golden goose - 'chocolate for Alzheimer's disease'. But, after much pushing, he will admit no more than that he expects to see food products on the European market that claim to aid and even increase brain function before the end of the decade.

Of course, in other places, these are on sale already. Coca-Cola in China is investing heavily in Chinese traditional medicine, and marketing some eye-catching products. There's Beautiful Life - a juice of rose, wild jujube and red date. It claims to 'improve Qi and blood circulation, to calm the mind, nourish the liver, release mental distress, invigorate the heart and spleen, and nourish yin to promote the production of body mind' (sic). Quite why Coca-Cola thinks it OK to make such claims to the Chinese, but not Europeans, is not explained. But Beautiful Life would probably not get past the EFSA.

The scientists in Dublin weren't sure that Dr Komentani's GABA chocolate would either. David Mela muttered that his research was 'very quick'. Another scientist said that GABA could never take off in Europe, because it was a close cousin of GHB (gamma hydroxybutyrate), the date-rape drug. But, jet-lagged or not, Dr Komentani was much in demand for the next two days- there were a lot of manufacturers interested in the European rights to GABA. Dr Komentani told me he is now working on a chewing gum based on a chemical in kiwi-fruit that will encase the tongue, thus stopping bad breath. And, on the GABA-date-rape connection, he pointed out that 200 grammes of tomatoes contain the same amount of GABA as a bag of the chocolate. 'That's not enough to cross the blood-brain barrier.' Coca-Cola also sells a GABA-laced sports drink in Japan: Sharp Charge 'for mental and physical fatigue recovery'.

My wife's experiment with GABA was inconclusive. After she'd eaten a packet she found herself lying on the sofa reading the paper, furious that she wasn't working. She felt she did more pacing, rather than less. But, hey, four days later 100 per cent of GABA eaters in our house got their dissertation in on time. And that is quite a statistic. OFM

Naturally Gorgeous

'Keeping you fuller for longer' Naturally Gorgeous drinks contain pine kernel oil which the manufacturers claim works by sending a signal to the brain saying you are full. Now sold at Waitrose.

GABA Chocolate

'For your struggle in a stressful society', GABA contains gamma-amino butyric acid, that occurs naturally in the human brain, and has been shown to calm post-menopausal women and students.