L-glutamic acid is a good amino acid that is found in most high-protein foods, such as cheese, sausage, and soy beans. It plays an important metabolic role during exercise and has been shown to enhance performance.
However, when its negative ionic form, glutamate, joins forces with sodium salt, it is altered into a bad amino acid known as Monosodium Glutamate (MSG), typically composed of 78% glutamate, 12% sodium, and 10% water. For some, MSG acts as a performance–inhibiting food additive. For those with a predisposition to allergies, MSG may be a life-threatening substance.
Health Issues Associated with Monosodium Glutamate
In 1995, an FDA Commission report acknowledged that an unknown percentage (now estimated at 15%) of the population could respond to the consumption of MSG with symptoms ranging from headache, nausea, drowsiness, or sweating to more severe symptoms like a rapid heartbeat, bronchospasm, or chest pain. It has recently become known as a contributing factor to obesity, migraines, and ADHD.
Doctors have commonly called this combination of MSG-induced symptoms the Chinese Restaurant Syndrome, but its effects are not limited to Chinese food. It is hypothesized that in humans symptoms are related to a sodium–potassium imbalance or due to the absence of enzymes needed to metabolize this sodium-rich anion.
A 1995 report by the Federation of American Societies for Experimental Biology (FASEB) identified people with poorly controlled asthma as one group that could develop the MSG symptom complex. They found an MSG dosage ranging from 0.5 to 2.5 grams was all that was required. Symptoms occurred within one hour after consuming a meal containing MSG on an empty stomach. Reactions were most likely when MSG was consumed in a clear soup or in large quantity.
Sources of Monosodium Glutamate
Protein-rich foods, such as canned vegetables, soups, and processed meats, often contain a form of MSG produced through a man-made process called hydrolysis. It is used as a food additive in the production of sausages or a flavor enhancer for frozen or dried products providing a sweet-salty taste.
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Knowledge of the amount of L-glutamic acid present in a particular food is of interest during the ripening of plants, to monitor food production, and to control the cheese making process.
Analysis of Monosodium Glutamate in Foods
A new system reagent kit that measures L-glutamic acid has recently been introduced for use with the discrete photometric analyzer (Thermo Scientific Gallery analyzer). Since the analyzer prefers to measure homogeneous liquid samples, the kit offers full instructions for sample preparation of foods, such as meat, vegetables, and fruit.
Dilutions required by the method are automated by the instrument and the easy to use test kit contains all the required reagents including a test standard.
- Peer-reviewed article: The Safety Evaluation of Monosodium Glutamate, J of Nutrition (link to abstract)
- Article: Monosodium Glutamate (MSG), Glutamic Acid (Glutamate), Glutamine Review (downloadable PDF)
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