Monosodium Glutamate: Will It Make Us Eat More or Less?

In a recent study, female subjects consumed chicken broth with or without monosodium glutamine (“MSG”) to see if this flavoring ingredient might alter their appetite. State of the art electronic devices that could detect their interest in eating certain foods monitored their intake during a subsequent meal. For those of you who order wonton soup, a chicken soup that usually contains MSG, in a Chinese restaurant, you might be interested in the results. Subjects exhibited more control over their food intake and ate less saturated fat after ingesting the broth with the MSG than after consuming the non-MSG soup.

In practical terms, this may mean you will eat more steamed broccoli and less battered shrimp or chicken after a cup of Chinese chicken soup. The authors suggest that the glutamine, an amino acid that functions as a neurotransmitter in the brain, in monosodium glutamate may be responsible in part for the eating behavior seen in the study. But before going on an MSG diet to lose a few pounds, it might be worthwhile considering that opposite effects have been described as well.

In 1990, a paper published by Rogers and Blundell recounted that subjects consumed broth (it was beef in this experiment) containing different amounts of MSG, and their food intake was measured about thirty minutes later. Initially after consuming the soup, subjects reported feeling full and not interested in eating. However, thirty minutes later their motivation to eat was higher after they consumed the MSG-containing soup than after soup without the ingredient. But this was not reflected in what they actually ate. They ate the same amount after each soup.

Scientist Takashi Sasano and his colleagues at Tohoku University in Sendai, Japan, concerned about the inadequate food intake of the elderly, found that giving them kelp-enriched tea could enhance their appetite. As reported in an article in New Scientist by Jessica Hamzelou in January 2015, the kelp, which is exceedingly rich in monosodium glutamate (MSG), stimulated food intake. The scientists speculated that an increase in saliva secretion was the reason.

So does MSG change your food intake? This is still in dispute. What is not in dispute is that the glutamate in monosodium glutamate is the source of a taste called “umami” by the Japanese. Kikunae Ikeda, who coined the term, discovered umami in 1908. There is no English word synonymous with umami; the closest related terms are savory, meaty, and broth-like. Because umami was originally a Japanese term, it was thought to be a taste associated only with Asian foods, and not one detected by Western taste buds.  However, it has been now established as a fifth basic taste along with sweet, sour, bitter, and salty.

Although most of us would immediately associate the umami taste with soy sauce, other Asian sauces such as oyster sauce, and the flavor imparted by MSG to soup powders and other processed foods, the umami taste is naturally present in foods we commonly eat.  Tomatoes, mushrooms, hard cheeses such as Parmesan and Roquefort, and also green tea contain high quantities of monosodium glutamate. Anchovies, an often disdained fish (except by the few who love them), contain substantial amounts of monosodium glutamate and have been used for thousands of years to impart the savory umami flavor to food. Garum, a condiment used in the Roman Empire, was as costly as perfume according to an NPR report by Howard Yoon in August 2009, and was prized for its ability to make foods taste, in his words, irresistible.  Anchovies have imparted this fifth taste in Indonesian, Korean, Filipino, Vietnamese, and Thai cooking over many centuries, although presumably adding purified MSG these days would keep the anchovies in the ocean.

And, according to Mr. Yoon, we fall prey to this savory taste when we find it hard to stop eating Doritos or instant ramen noodles.

MSG is both good and bad for us. It has received decades of bad press because of the so-called Chinese restaurant syndrome, a cluster of symptoms such as headache, flushing, tingling, rapid heartbeat, sweating, nausea and burning sensations in the face. After years of extensive research, it has been found that a small percentage of people experience an acute short-lived reaction to MSG. But this is not why MSG is bad. It is bad because, as an additive to many highly processed foods as well as snacks, its umami taste causes us to fill up on foods that, at the very least, don’t really nourish us, and at worst, cause us to eat too many calories in the form of junk food.

But monosodium glutamate could also induce us to eat foods that are healthy, but are avoided because their taste is so boring. Think of how many people do not eat vegetables. They have made up their minds, perhaps as children being forced to eat them, that when they grow up, they will never eat a carrot or a serving of spinach again. What if they were presented with vegetables that have the savory taste of umami? What if the salads and vegetables they disdain had the “lip-smacking flavor“ of a Dorito or ramen noodles and were suddenly craved? An increase in vegetable consumption would certainly improve the quality of our nutrient intake and might even reduce calories.

The article by Yamaguchi and Ninomiya points out that Western foods traditionally rely on high-fat ingredients like butter, oil, and cream to deliver taste and carry the taste of other ingredients. This is why bacon fat or melted cheese or heavy cream bring a deliciousness to dishes that can’t be mimicked by skim milk and canola oil. But, as they point out, much pleasure in the taste of foods is also found in foods delivering that fifth taste—and without the caloric cost.

Regardless of whether MSG makes us eat more or less, what it can do through the fifth taste sense, umami, is to bring more nutritional sense to our diet.

References

“Neurocognitive effects of Umami: Association with eating behavior and food choice,” Magerowsski G Giacona G, Patriarca, et al Neuropsychopharmacology   2018; 43: 2009 -2016.

“Umami and appetite: Effects of monosodium glutamate on hunger and food intake in human subjects” Rogers P and Blundell J Physiol Behav. 1990 48:801-4.

“Umami and Food Palatability,” Yamaguchi S and Ninomiya K The Journal of Nutrition 2000; 130: 9212-9265s

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