I once met an elderly lady in the grocery store who was looking for the “no MSG” printed on the soup label to make sure she was not buying the product which everyone tells her is nutritionally unhealthy. I inquired if she had any reaction to consuming MSG-containing foods such as tomato, cheese, mushroom, meat, fish or Chinese food and the answer was negative. If this compound is facing so much negative publicity, let us see why it is so, considering the fact that this organic compound is present in almost all foods we consume.
MSG is the sodium salt of glutamic acid which is the most abundant amino acid in all proteins. Japanese found early on (Ikeda in 1908) that the active ingredient in sea tangle, which they used extensively to enhance the savoriness in soup is the sodium salt of glutamic acid. In the 1960s, Kuninaka found that in human taste sensation, there exist a remarkable synergy between glutamate (MSG) and 5’-nucleotides (5’-IMP and 5’-GMP) present in mushroom and bonito. Today, these three products which enhance the flavor and brothiness of less savory products are referred to as umami compounds. Although there has been great deal of studies conducted on the properties of these three compounds, the mechanism by which it enhances savory flavor is not worked out yet.
However, extensive studies have revealed that the receptor sites for these three umami compounds are different from the receptor sites related to primary taste stimuli, namely, sweet, sour, salty and bitter. Because of this unique nature, it is now considered as the fifth basic taste.
During evolution, why did living forms develop specific receptors for sweet, sour, salty, bitter, and umami in the oral cavity? A simple explanation is to address nutritional problems and promote sustenance. For example, sweet receptors can detect much needed calorie foods; Salt receptors can provide Na ions to maintain sodium balance; Bitter perception can help avoid poisonous material; avoidance of excess sour compound to prevent tissue damage; and Umami receptors for living things to get attracted to the much needed proteins and amino acids for synthesis of enzymes and other nitrogenous compounds to maintain the biological functions. If Glutamate (MSG), which is a key Umami compound, is totally avoided from our food, which in essence is a way to completely avoid consumption of the much needed protein, the consequences can be disastrous. If that had been the case in evolution, the elderly lady I met in the grocery store may not have been there to read the label, in the first place.
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Dr. Nagodawithana received his PhD from Cornell University, NY and has worked in the food biotech world for nearly 40 years. He is the author or co-author of 5 Biotechnology books. He is famous among ‘savory flavor’ scientists - but most of all, he is as a great teacher and an even better friend.
ReplyDeleteIf MSG replicates a "natural" salt, why the metallic headache and jaw ache reaction that some people have?
ReplyDeleteI love MSG, it's why we all love Doritos! Since foods with MSG are typically associated with high levels of sodium too, maybe we need to be looking at sodium as the culprit of headaches and jawaches, not MSG.
ReplyDeleteResponse from Dr. Nagodawithana:
ReplyDeleteTo Anonymous: According to reputable medical studies, fewer than 3% of us are allergic to foods and that small percentage includes those allergic to eggs , milk, fish, nuts, peas, clam, oysters, etc. It is thus safe to say that only a tiny percentage (<1%) can truly react to MSG and that too, according to reliable studies is when heavy amounts of MSG is administered in large oral doses in an empty stomach. This tells me that during evolution, very few have become “less equal” that other.
Experience tells me one other thing. That is, if many of those who claim as affected by MSG when they eat those foods, and they know it, they have a problem. But if they don’t know it, chances are, many of them will do fine. Some of the placebo-controlled trials have led to such conclusions.
A wide range of events and situations can alter conditions in the brain that bring on nerve excitation and trigger migraines. For example, for truly affected by MSG, these conditions may include emotional stress, intense physical exertion, lack of sleep, certain foods or chemical compounds etc, etc. and in such individuals, when these conditions are borderline, MSG or some other chemical may serve as a instant trigger to cause the migraine. People who eliminate the MSG-containing foods may be bringing the condition less favorable to have the reaction.
Animal studies which showed a reaction with high doses may be overcharging the synapses with neurotransmitter, glutamate, perhaps, causing abnormal firing and inflammation and a drop in serotonin (serotonin is a natural pain reliever). Decreased serotonin sends out pain messages we perceive as headaches. After serotonin levels return to normal, most headaches tend to subside. In the case of those sensitive to MSG, the MSG taken might tip the balance of glutamate and acetylcholine already produced by the body on the synapses thereby causing the headache. These are my thoughts only since I have no medical background.
To Kathy K: MSG has a lower % Na (12% Na) than common salt (39% Na). Hence ingredient suppliers have products with lower (example 30%) Na, but with similar salt perception as with 100% salt, by including MSG in the formulation. The point is, by including MSG, the salt (Na) level can be reduced by 30% or so with out flavor defects.