If MSG is so bad for you, why doesn't everyone in Asia have a headache?

This is a condensed version from an article i read in 2005.

Japan a century ago. Professor Kidunae Ikeda eats a broth of vegetables made by his wife. It is - as usual - delicious. The professor asks what is the secret of her wonderful soup. Mrs Ikeda points to the strips of dried seaweed she keeps in the store cupboard. This is kombu, a heavy kelp. Soak it in hot water and you get the essence of dashi, the stock base of the tangy broths and consommés the Japanese love.

This is the professor's 'Eureka!' moment. Mrs Ikeda's kombu is to lead him to a discovery that would bring about the world's longest-lasting food scare. Professor Ikeda was one of many scientists working on the biochemical mechanics which inform our perception of the world. By 1901 they had drawn a map of the tongue, showing, crudely, the whereabouts of the different nerve endings that identify the four accepted primary tastes, sweet, sour, bitter and salty.

But Ikeda thought this matrix missed something. 'There is,' he said, 'a taste which is common to asparagus, tomatoes, cheese and meat but which is not one of the four well-known tastes.' He decided to call the fifth taste 'umami' - a common Japanese word that is usually translated as 'savoury' - or, with more magic, as 'deliciousness'. And so he and his researchers began their quest to isolate deliciousness.

By 1909, He'd found a chemical that was exactly the same as those of glutamic acid, an amino acid produced by the human body and present in many foodstuffs. When the protein containing glutamic acid is broken down - by cooking, fermentation or ripening - it becomes glutamate - what causes the taste sensation "umami". Not long after, the professor patented MSG. He began to market it as a table condiment called Aji-no-moto ('essence of taste').

The food chemicals giant Ajinomoto Corp, now owned by General Foods, pumps out a third of the 1.5 million tons of monosodium glutamate we eat every year - 'Ajinomoto' means MSG.

We now know that glutamate is present in almost every food stuff, and that the protein is so vital to our functioning that our own bodies produce 40 grams of it a day. Probably the most significant discovery in explaining human interest in umami is that human milk contains large amounts of glutamate (at about 10 times the levels present in cow's milk). Babies have very basic taste buds: it's believed that mother's milk offers two taste enhancements - sugar (as lactose) and umami (as glutamate) in the hope that one or other will get the little blighters drinking. Which means mothers' milk and a packet of cheese'n'onion crisps have rather more in common than you'd think.

When you next grate parmesan cheese onto some dull spaghetti, what you will have done in essence is add a shed-load of glutamate to stimulate your tongue's umami receptors, thus sending a message to the brain which signals (as one neuro-researcher puts it) 'Joy and happiness!' Supper is rescued - and your system has added some protein and fats to a meal that was all carbohydrate.

Ripe cheese is full of glutamate, as are tomatoes. Parmesan, with 1200mg per 100 grams, is the substance with more free glutamate in it than any other natural foodstuff on the planet. Almost all foods have some naturally occurring glutamate in them but the ones with most are obvious: ripe tomatoes, cured meats, dried mushrooms, soy sauce, Bovril and of course Worcester sauce, nam pla (with 950mg per 100g) and the other fermented fish sauces of Asia.

Your mate, Marmite, with 1750mg per 100g, has more glutamate in it than any other manufactured product on the planet - except a jar of Gourmet Powder straight from the Ajinomoto MSG factory. On the label, Marmite calls it 'yeast extract'. Nowhere in all their literature does the word 'glutamate' appear. I asked Unilever why they were so shy about their spread's key ingredient, and their PR told me that it was because it was 'naturally occurring ... the glutamate occurs naturally in the yeast'.

As they put monosodium glutamate into production, Professor Ikeda and his commercial partners found that making stable glutamate from the traditional seaweed and salt was unnecessary. They developed a much simpler and cheaper process using fermented molasses or wheat - eventually manufacturers realised that almost any protein can be broken down to produce it.

The product took off, immediately, and within a few years Ajinomoto (which was now the company's name) was selling MSG across Asia. The breakthrough to America came in the aftermath of World War Two. Like pizza and vermouth, MSG was a taste American soldiers brought home with them. They weren't aware that MSG was what they'd liked in Japan - but the US Army catering staff noticed that their men enjoyed the leftover ration packs of the demobilised Japanese Army much more than they did their own, and began to ask why.

But MSG's conquest of the planet hit a major bump in April 1968, when, in the New England Journal of Medicine, a Dr Ho Man Kwok wrote a chatty article, not specifically about MSG, whose knock-on effects were to panic the food industry. 'I have experienced a strange syndrome whenever I have eaten out in a Chinese restaurant. And so was born Chinese restaurant syndrome (CRS) and a medico-academic industry dedicated to the researching and publicising of the dangers of MSG - the foreign migrant contaminating American kitchens. Shortly after Dr Ho came Dr John Olney at Washington University, who in 1969 injected and force-fed newborn mice with huge doses of up to four grams/kg bodyweight of MSG. He reported that they suffered brain lesions and claimed that the MSG found in just one bowl of tinned soup would do the same to the brain of a two-year-old.

The fact is that, since the eighties, mainstream science has got bored of MSG. Some research continues; in 2002, for example, New Scientist got very excited over a report that MSG might damage your eyesight, after Japanese scientists announced that they had produced retinal thinning in baby rats fed with MSG. However, at no time has any official body, governmental or academic, ever found it necessary to warn humans against consuming MSG.

Google MSG today, and you'll find it blamed for causing asthma attacks, migraines, hypertension and heart disease, dehydration, chest pains, depression, attention deficit disorder, anaphylactic shock, Alzheimer's and Parkinson's diseases and a host of diverse allergies.

The anti-additive movement admits that 'natural' and 'industrially produced' glutamate are chemically the same, and treated by the body similarly. So why doesn't anyone ever complain of a headache or hyperactivity after a four cheese and tomato pizza (where there's easily as much glutamate as in an MSG-enhanced chicken chow mein)?

Their answer is that the industrial fermentation process introduces contaminants. This is possible, of course, but it ignores the fact that whole swaths of the planet - including East Asia, where I live - do not have any problem with MSG.

I bought a little bag of Ajinomoto from the corner shop on our Bangkok street and tried it, a gram (the tip of a teaspoon) at a time.

By itself it tasted of almost nothing. So I beat up and fried two eggs, and tried one with MSG, one without. The MSG one had more egg flavour, and didn't need any salting. I tried the crystals on my son's leftover pieces of chicken breast (definitely more chickeny). I tried it in a peanut butter sandwich (nothing). On Weetabix with milk (interesting, sort of malty) and on Weetabix with milk and sugar (thought I was going to be sick).

My friend Nic came round. He told me about a Japanese restaurant he'd been to that gave him headaches and a 'weird tingling in the cheeks' - until he told them to stop with the MSG. Then he was fine, he said. I nodded and I served him two tomato and chive salads; both were made using the very same ingredients but I told him one plate of tomatoes was 'organic', the other 'factory-farmed'. The organic tomatoes were far better, we agreed. These, of course, were the tomatoes doused with mono sodium glutamate.

Then we ate mascarpone, parma ham and tomato pizza. Nic felt fine. So did I. I had ingested, I reckoned, a good six grams of MSG over the day, and probably the same again in free glutamate from the food - the equivalent of eating two 250g jars of Marmite.

I've thrown the Ajinomoto out now. It works, but it was embarrassing - no need to have MSG in the kitchen. If I want extra glutamate in my food I'll use parmesan, or tomato purée, or soy sauce. Or like Mrs Ikeda, boil up some kelp.