Debate Over Safety of MSG Heats Up Again : Health: There’s no firm evidence linking MSG to health problems, but ‘sufferers’ want the additive regulated. The FDA will review labeling rules.
How can a government regulate a health problem if it’s 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.
Kenney tried again a year later, 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 reemergence of the MSG controversy has come even though there is no definitive scientific evidence confirming any of the charges that MSG is harmful. 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 the 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 young rodents force-fed high doses of MSG were developing brain lesions, a finding that suggested 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.
The FDA’s response to the latest tide of complaints has been a promise to reevaluate the 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 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 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 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.”
But few of Olney’s colleagues believe there is enough evidence against MSG to warrant immediate action. There are also a number of questions about his research. For example, glutamate breaks down very quickly once it enters the body. The only way for Olney to get glutamate levels high enough in the bloodstream of animals to cause brain damage was to force-feed them the chemical in high quantities over a very short period of time. In other studies that allowed allowed the animals to eat MSG at their own pace, the animals never showed any adverse effects.
Olney defends his method as the best approximation of the way 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.
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. These are areas 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.
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, Va., 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% 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% 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.
Clouding the picture still more is the fact that many symptoms attributed to MSG might be caused by something else. In a recent survey of 3,222 people, for example, 43% 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, with or without MSG.
