ABSTRACT
Monosodium Glutamate is a widely used food additive and flavor enhancer that is present in most soups, salads and processed meat and also present in packaged food without appearing on the label. This could result to inadvertent consumption of monosodium glutamate in high concentrations. The present study investigated the effect of monosodium glutamate on liver and testes of adult male wistar rats, by daily oral exposure of different doses. Wistar rats (n=20) of the average weight of 250-280g were randomly assigned to four group, control, group A, B and C in which (n=5) rats are contained in each group. By the end of the stipulated number of days for the exposure, their organs were subjected to histopathological, biochemical hematological and sperm analysis. The results obtained from these examinations showed the deleterious effect of monosodium glutamate on the liver and fertility. Statistical analysis on sperm motility using ANOVA were carried out and revealed significant difference in the mean percentage of motile cells but no significant difference in the mean percentage of slow motile cells and non motile cells. The liver function parameters revealed no significant difference in the ALP, and AST while there is significant difference in ALT. The hormonal parameters revealed no significant difference in the Luteinizing Hormone, and testosterone but significant difference in the follicle stimulating hormone. However, Monosodium glutamate consumption should be minimized, if not completely avoided to curb its deleterious effect to the hepatocytes and male fertility.
CHAPTER ONE
- INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Monosodium Glutamate occurs naturally in many foods, such as tomatoes and cheeses. People around the world have eaten glutamate-rich foods throughout history. In 1907, Kikunae Ikeda began a research project to identify the substance in kelp (Laminariaceae) that produced a unique taste favoured in soup stocks in Japan. His research was based on the hypothesis that one or more taste substances may exist in Kelp that could not be categorized as bitter, sour, salty, or sweet (the known basic taste at the time). He named this putative fifth basic taste umami. More generally, Ikeda hoped that, if successful, the results of his research might have a commercial application, such as in a seasoning that would contribute to the improvement of human nutrition in Japan. In 1908, he identified the Umami taste component of kelp as L-glutamate. He filed a patent claim for a process to produce a new seasoning consisting mainly of a salt of L-glutamic acid (Ikeda, 1908). Saburousuke Suzuki, a well-known entrepreneur in the chemical and pharmaceutical industry, then began collaboration with Ikeda to produce and commercialize the seasoning. In 1909, this seasoning was named AJI-NO-MOTO and was registered as a trademark. AJI-NO-MOTO was then known and widely used throughout the world.
1.2 STATEMENT OF THE RESEARCH PROBLEM
Monosodium glutamate was originally designated as a Generally Recognized as Safe (“GRAS”) ingredient by the FDA in 1958, along with other commonly used food ingredients like salt and baking powder (Singh, 2005). Specifically the relevant portion of the United States Code of Federal Regulations states, “It is impracticable to list all substances that are generally recognized as safe for their intended use. However, by way of illustration, the Commissioner regards such common food ingredients as salt, pepper, vinegar, baking powder and monosodium glutamate as safe for their intended use” (FDA, 2017). The safety of MSG has been repeatedly reaffirmed by a number of different sources within the scientific community, including the FDA, since that time. In 1987, the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization and the World Health Organization placed MSG in the safest category of food ingredient (Singh et al., 2005). In addition, a report done in 1991 by the European Communities’ Scientific Committee for Foods confirmed this finding, classifying the “acceptable daily intake” of MSG as “not specified,” which is the most favorable categorization for a food ingredient. The Council on Scientific Affairs of the American Medical Association also weighed in on the issue, stating that glutamate has not been shown to pose a “significant health hazard” in any form (Singh et al., 2005). And yet despite the seemingly general scientific consensus that MSG is safe, the food ingredient has nonetheless been subject to overwhelming controversy in the past several decades.
Moreover, the FDA’s position on MSG labeling has remained relatively static for some time, and yet has become a key component in the larger MSG controversy. The FDA requires labeling of all ingredients in processed and packaged foods. Therefore, whenever MSG is added to a food product, it must be listed on the ingredient list under its common name, “monosodium glutamate.” However, when glutamate-containing ingredients, such as Parmesan cheese, soy sauce and hydrolyzed proteins, are included in a food, they are to be listed by their common name (Singh et al., 2005). The FDA, in 1993, proposed adding the phrase “contains glutamate” to certain protein hydrolysates that contain substantial amounts of glutamate, however this initiative was never finalized. For a food ingredient that has received so many safety approvals and for which there is virtually no confirmed scientific evidence of deaths or serious illness, MSG has nevertheless created what can essentially be termed “mass hysteria” in the general population. MSG has been faulted for a whole host of medical conditions, from headaches to cardiac arrhythmia; it has even been blamed for murder (Warren, 1993). One of the most contested issues that arise in the MSG debate is the question of whether to base findings of MSG safety solely on double-blind scientific studies or to take into consideration the anecdotal evidence. A great deal of the outcry against MSG based on potential adverse health effects relies on these personal accounts of MSG intolerance. These types of reports, though not inherently invalid, do raise scientific concerns in that these episodes cannot be directly linked to the ingestion of MSG, and could in fact be attributed to a variety of other factors. A medical dictionary blurb defines Chinese Restaurant Syndrome as follows:
The syndrome refers to a group of symptoms that can occur after eating Chinese food. The symptoms can include headache, sweating, facial pressure or swelling, nausea, numbness or burning around the mouth, chest pains and heart palpitations. Typically, the symptoms are temporary and not life-threatening, said William Geimeirer, a Wilmington-based allergist. The food additive monosodium glutamate, or MSG, which is commonly used as a food preservative, flavor enhancer or meat ten-derizer, has been implicated but never proven to be the cause, according to the National Institutes of Health. The condition was first reported in 1968, the Institute said. Treatment depends on the symptoms. Most people recover on their own (Singh et al., 2005)
The term “CRS” was first coined in 1968 by Dr. Robert Ho Man Kwok to describe the above-noted collection of symptoms he experienced after eating Chinese food. Anecdotal reports of MSG inducing CRS have been repeatedly subject to scientific examination. The vast majority of these studies have been relatively unfavorable, or at best inconclusive, towards these anti MSG claims. A study by two Italian scientists, P.L. Morselli and S. Garatini of the Institute of Pharmacologic Research in Milan, indicated that CRS may ultimately be a result of “autosuggestion.” In a double-blind crossover study, the two scientists examined 17 males and seven females, between the ages of 18 and 34. The two administered 3 gram doses of MSG via 150ml of beef broth and evaluated the participants every 20 minutes for a three hour period. There were two groups of subjects, one group that received broth with MSG and one group that received broth without MSG. An examination of the test results revealed that the group that had received the broth without MSG reported a number of CRS symptoms, including headache, flushing and tightness in the chest, whereas the group that received the actual MSG broth reported no such symptoms. Other researchers have reached similar conclusions with regard to the scientific link between MSG and CRS. Richard Kenney, MD, of George Washington University has done a number of different studies to examine whether there is in fact any scientifically credible evidence indicating a food intolerance to MSG. In one study, Kenney fed 60 subjects a variety of liquids, including orange juice, black coffee, flavored milk, spiced tomato juice and a two percent MSG solution. Kenney’s results indicated that six subjects reacted to coffee, six to spiced tomato juice and only two subjects responded to the MSG, indicating that “MSG was not unique in producing symptoms typical of CRS.” Kenney did a follow-up double-blind study using subjects who claimed that they suffered adverse reactions after ingesting foods with MSG. The test participants drank a “soft drink” solution for four days, on two of which the solution contained 6 grams of MSG. Once again, Kenney’s results proved unfavorable to the anti-MSG camp. Two of the six participants reacted to both of the solutions (with and without MSG), and the other subjects reacted to neither of the solutions. Indeed, there are number of other studies that have produced similar results, failing to produce the adverse reactions that many individuals associate with dietary intake of MSG. One researcher has attempted to explain the existence of these “CRS-like” symptoms even without exposure to MSG, attributing some of these postprandial adverse reactions to high histamine levels in some foods (Chin, 1989). Of course, these studies and their accompanying results are not without critics.
One of the most outspoken opponents of MSG, Dr. Adrienne Samuels, has publicly disapproved of many of these studies on grounds that they have been industry-sponsored, “sloppy in . . . design and execution; focus[ing] on areas which were irrelevant to an understanding of the toxic effects of MSG; and . . . even . . . involved in clear-cut scientific fraud.” Specifically, Samuels suggests that some of the placebo studies were inappropriate since the placebos themselves contained glutamate resulting from manufacture. Samuels and her husband, Jack Samuels, who claims to suffer life-threatening symptoms following ingestion of MSG are by far the most vocal of the anti-MSG activists. Their claims seem to center primarily on the fact that these studies are funded by industry and that the FDA has been bought by these very same industry players. However, there is evidence of studies conducted independent of industry that have resulted in the same dubious conclusions regarding the claim that MSG causes CRS; moreover, there is indication that these anti-MSG activists may sometimes attribute industry ties to those who do not hold them.
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