In the article on Monosodium glutamate (Focus, March 13), scientist Richard Kenney was incorrectly identified. He was chairman of the physiology department at George Washington University when he conducted his studies on MSG. (Published 4/3/90)

How can a government regulate a health problem if it is not sure it even exists?

Never mind. A group of activists wants it done anyway.

Suddenly, the controversy over the widely used flavor enhancer MSG has dramatically resurfaced.

MSG "sufferers" have formed a lobby group -- the National Organization Mobilized to Stop Glutamate (NOMSG) -- which is speaking out regularly about what it considers the additive's dangers.

A group of prominent neuroscientists has urged the Food and Drug Administration to look more closely at new reports that MSG might be a neurotoxin -- a substance that can destroy nerve tissue.

Meanwhile, top FDA officials have pledged to reassess the rules governing the labeling of products containing the food additive.

The last word on MSG was supposed to be the findings 10 years ago by George Washington University scientist Robert Kenney. In an attempt to verify the so-called "Chinese Restaurant Syndrome," Kenney fed 35 people a soft drink laced with the food additive MSG.

The results were dramatic. Following the precise pattern of symptoms commonly attributed to the flavor enhancer, the group reported headaches, nausea, stomach distress, salivation and weakness.

The only problem was that when Kenney checked his control group of 35, who were given an MSG-free version of the same drink, they reported the same symptoms with the same frequency.

A year later Kenney tried again, comparing an MSG solution with ordinary fruit juice. But this time the allegations of allergic and toxic reactions that have been levied against MSG for the better part of 20 years received an even bigger setback. Orange and tomato juice, he found, caused the symptoms commonly associated with MSG more often than MSG did.

"A lot of people are happy to report anecdotes, but when I tested people I just didn't find the same reactions," he said.

Despite his work and similar findings of a number of other scientists over the past decade, today the list of symptoms allegedly caused by MSG has grown to include asthma, diarrhea, muscle swelling and heart irregularities.

The re-emergence of the MSG controversy has come even though there is no definitive scientific evidence confirming any of the more serious charges that MSG is harmful to humans. Indeed, for many scientists and policy makers, the MSG issue has come to pose something of a dilemma. Is it possible, some ask, that the many Americans who believe themselves to be sensitive to MSG are either allergic to something else or are imagining things?

MSG is a version of glutamic acid, one of the 20 amino acids naturally present in nearly all protein. Once derived from seaweed and now produced through fermentation of molasses, glutamate has been used in Oriental cooking as a flavor enhancer for nearly 2,000 years.

Since the turn of the century, the amount of MSG has steadily grown, to the point where the average American now consumes about half a gram of MSG per day in everything from canned soup to fast food.

It wasn't until 20 years ago, however, that doubts were raised about the safety of MSG. In a short letter to the New England Journal of Medicine, a doctor described a variety of symptoms -- including general weakness, throbbing sensations and numbness that spread from his neck to both arms -- that he commonly experienced while eating Chinese food flavored with MSG.

Adding to the controversy was the publication in the early 1970s of studies showing that baby rodents force-fed high doses of MSG were developing brain lesions, a finding that suggested that food products containing MSG might be harmful to children.

Since then, the ranks of those claiming sensitivity to MSG has steadily grown. In the NOMSG organization, for example, there is a San Diego woman who says she had swelling in her joints, a 20-year-old Kansas City woman whose doctors thought she had multiple sclerosis, another woman with skin rashes, a man with migraines and dozens more with ailments they all trace to food laced with MSG.

"We had a child who seemed happy, but every once once in a while he'd {defecate} in his pants," said Arthur Colman, a San Francisco physician. "He became a real behavior problem. It was hard to see what was wrong. Then we started him on a non-MSG diet. He gained 20 pounds, and his psychiatrist said it was one of the most remarkable transformations he'd ever seen . . . I'll bet there are thousands of families with children like this."

The FDA's response to the latest tide of complaints has been a promise to re-evaluate the current labeling rules on the chemical, which permit MSG made by certain manufacturing techniques to be labeled as "natural flavors" or "seasonings" instead of by its chemical name. But beyond that, agency officials say that there simply isn't enough evidence to draw any firm conclusions from any of the apparently MSG-related phenomena.

Take, for example, the research suggesting a link between MSG and brain damage in rats. The concern is based on the fact that glutamate, which is found naturally in large quantities in the brain, acts as a neurotransmitter, stimulating brain cells. However, when released in excess quantities -- as can happen in a stroke, for example -- it becomes a neurotoxin, stimulating brain cells so much that they die.

The question is whether glutamate in food can have the same effect. In research beginning 20 years ago, Washington University neurophysiologist John Olney suggested that in the case of infants -- whose brains are more vulnerable than those of adults -- it could. In tests on infants in seven species -- ranging from monkeys to rats -- Olney found MSG-related brain damage resulting in obesity, growth retardation and reproductive dysfunction. Since the amounts of MSG Olney administered to the animals were roughly comparable to those a small child might get from a bowl of canned soup, Olney warns that children are at risk from MSG.

"There are infants around the world who are being exposed to MSG and potentially damaged by it," said Olney. "I'm not saying it should be banned. But the levels in foods have got to be regulated."

Olney's research is taken seriously enough that at a meeting last October, the Social Issues Committee of the Society for Neuroscience agreed to ask the FDA to look more closely at how MSG and other amino acids might cause brain damage.

"There was a sense among some of the scientists that the FDA is considering data that comes from companies with a vested interest in MSG over data generated in research labs that say it is problematic," said Columbia University researcher Nancy Wexler, who also heads the Hereditary Disease Foundation. "If there is a potential problem, especially with an additive that doesn't serve any real purpose, we want it taken seriously."

"Olney has raised a logical concern," said Dennis Choi, a neuroscientist at Stanford University. "Should we be worried about glutamate as a food additive if there is this experimental observation that it can injure a young brain. This is a serious observation, and it deserves consideration."

But few of Olney's colleagues believe there is enough evidence against MSG to warrant immediate action. There are also a number of question marks about his research. Glutamate, for example, breaks down very quickly once it enters the body. The only way for Olney to get glutamate levels in the bloodstream of animals high enough to cause brain damage was to force-feed them the chemical in high quantities over a very short period of time. Other studies, allowing the animals to eat MSG at their own pace, never showed any damage.

Olney defends his method as the best approximation of the way that humans eat MSG in, for example, a bowl of soup -- in large and concentrated doses. Others disagree. "It's seriously flawed research," said Stanley Gershoff, dean of the Tufts University School of Nutrition. "It just happens that is just not the way humans consume glutamate." By using a stomach tube, Gershoff says, Olney also bypassed the gastrointestinal tract, which contains enzymes that help to break down glutamate before it reaches high levels in the blood.

"My feeling is that if you have a hypothesis based on animal studies that MSG is toxic, then you should go out and find someone who has been damaged by it," Gershoff said. "{Olney has} had 20 years to do this, and he hasn't done it. That's why it's irresponsible for him to go around making allegations."

Even if true, however, Olney's theory accounts only for MSG toxicity in children. The chemical's effects on the brain do not show up in experiments on adult animals and, what's more, adult brains are protected by a "blood-brain barrier" that is not fully present in childhood. Why some adults should also report a wide range of allegedly MSG-related symptoms is another, even more baffling question.

Take the most commonly reported and mildest of MSG symptoms -- the feelings of tightness in the chest, neck and upper back areas. This is the area where the body "refers" pain from the throat, leading some to speculate that MSG simply irritates the esophagus. This would also explain why other substances -- like orange juice and, in some studies, black coffee -- appear to have the same effect, because they too irritate the esophagus.

But what of the more serious symptoms attributed to MSG? Experts say the question is wide open. One theory arises from allergy testing done by a Reston firm, Health Studies Collegium, which has measured the responses of more than 8,000 people to some 235 food additives and chemicals. According to the firm's president, Russell Jaffe, 3.8 percent of the general population were positive when tested for MSG sensitivity. However, of those afflicted with a variety of medical conditions -- asthma, inflammatory bowel disease, rheumatoid arthritis -- close to 50 percent registered positive for MSG, leading him to believe that certain types of bodily tissue damaged by disease could be sensitive to even small levels of glutamate in the blood.

According to Jaffe, the diarrhea and cramps associated with MSG could be caused when the chemical gains access to the bowel through a damaged or unusually permeable intestinal wall. "Some people are exquisitely hypersensitive," Jaffe said. "They only need to be exposed to tiny amounts of material to get a profound symptomatic response."

But Jaffe admits he isn't sure how the sensitivity to MSG that he measures correlates to the symptoms suffered by some MSG eaters. He also says that when he exposes patients to pure glutamate, he doesn't find any problem at all, raising the question of whether the culprit is in fact the chemical or some byproduct of the fermentation process used to make it.

Clouding the picture still more is the fact that many symptoms attributed to MSG might be caused by something else entirely. In a recent survey of 3,222 people, for example, 43 percent of respondents reported at least one of a number of unpleasant symptoms -- from diarrhea to heartburn to abdominal cramps -- in association with consumption of food generally, with or without MSG.

Indeed, over the years as the list of symptoms attached to MSG has changed, some researchers have begun to suspect that MSG has become a convenient scapegoat for a number of other, unexplained phenomena.

"Over the course of time, there is almost no adverse reaction that has not been laid at the door of MSG," said Kenney. "In the period 1968 to 1972, the things that were being reported were these sensations of burning and tightness in the chest. If you look at the early '70s, the accent was on headaches, with the burning and tightness taking a back seat. Then if you look at the 1980s, complaints have moved to the {gastrointestinal tract} and the burning and tightness has disappeared altogether. It's a puzzle. It almost seems like certain adverse reactions become fashionable.

"This is the problem with something that is as well-known and widely used as MSG," said Kenney. "There will always be anecdotes. And no amount of evidence will ever get rid of an anecdote."