The absorption by human volunteers of glutamic acid from monosodium glutamate and from a partial enzymic hydrolysate of casein

Patho-physiological and toxicological aspects of monosodium glutamate

Nowadays, the life-line of urban population has been formed by commercial foods due to industrialization, urbanization, and rapid increase in working class. Commercial foods are time and energy saving foods but it compromising the nutritional value of foods. The term adulteration refers to the deliberate addition of compound which is usually not present in food. These compounds are known as food additives or food adulterant. Monosodium Glutamate (MSG) is one of the most common food additives. Several studies revealed that MSG has toxic effect on fetal development/fetus, children's, adolescent, and adults. Physiological complication associated with MSG toxicity are hypertension, obesity, gastrointestinal tract troubles, and impairment of function of brain, nervous system, reproductive, and endocrine system. The effect of MSG depends upon its dose, route of administration and exposure time. Public awareness may play a major role in controlling the food adulteration by working in collaboration with National testing facilities to scrutinize each commercial food article from time to time. The aim of this review article is to highlight the deleterious impact of MSG on human health.

Blood Glutamate Levels Are Closely Related to Acute Lung Injury and Prognosis after Stroke

Background

Acute lung injury (ALI) is a serious complication of stroke that occurs with a high incidence. Our preclinical results indicated that ALI might be related to blood glutamate levels after brain injury. The purpose of this study was to assess dynamic changes in blood glutamate levels in patients with stroke and to determine the correlation between blood glutamate levels, ALI, and long-term prognosis after stroke.

Methods

Venous blood samples were collected from controls and patients with stroke at admission and on the third and seventh day after the onset of stroke. Patients were followed for 3 months. The correlations among blood glutamate levels, severities of stroke and ALI, and long-term outcomes were analyzed, and the predictive values of blood glutamate levels and severity scores for ALI were assessed.

Results

In this study, a total of 384 patients with stroke were enrolled, with a median age of 59 years. Patients showed significantly increased blood glutamate levels within 7 days of stroke onset (p < 0.05), and patients with more severe injuries showed higher blood glutamate levels. Moreover, blood glutamate levels were closely related to the occurrence (adjusted odds ratio, 3.022, p = 0.003) and severity (p < 0.001) of ALI and the long-term prognosis after stroke (p < 0.05), and they were a more accurate predictor of ALI than the more commonly used severity scores (p < 0.01).

Conclusion

These results indicated that an increased blood glutamate level was closely related to the development of ALI and a poor prognosis after stroke.

Clinical Trial Registration

http://www.chictr.org.cn, identifier ChiCTR-RPC-15006770.

Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study

Monosodium glutamate (MSG) has a long history of use in foods as a flavor enhancer. In the United States, the Food and Drug Administration has classified MSG as generally recognized as safe (GRAS). Nevertheless, there is an ongoing debate exists concerning whether MSG causes any of the alleged reactions. A complex of symptoms after ingestion of a Chinese meal was first described in 1968. MSG was suggested to trigger these symptoms, which were referred to collectively as Chinese Restaurant Syndrome. Numerous reports, most of them anecdotal, were published after the original observation. Since then, clinical studies have been performed by many groups, with varying degrees of rigor in experimental design ranging from uncontrolled open challenges to double-blind, placebo controlled (DBPC) studies. Challenges in subjects who reported adverse reactions to MSG have included relatively few subjects and have failed to show significant reactions to MSG. Results of surveys and of clinical challenges with MSG in the general population reveal no evidence of untoward effects. We recently conducted a multicenter DBPC challenge study in 130 subjects (the largest to date) to analyze the response of subjects who report symptoms from ingesting MSG. The results suggest that large doses of MSG given without food may elicit more symptoms than a placebo in individuals who believe that they react adversely to MSG. However, the frequency of the responses was low and the responses reported were inconsistent and were not reproducible. The responses were not observed when MSG was given with food.

Abnormal glutamate metabolism in an adult-onset degenerative neurological disorder

In patients with recessive, adult-onset olivopontocerebellar degeneration associated with a partial deficiency of glutamate dehydrogenase, the concentration of glutamate in plasma was significantly higher than that in controls. Plasma alpha-ketoglutarate was significantly lower. Oral administration of monosodium glutamate resulted in excessive accumulation of this amino acid in plasma and lack of increase in the ratio of plasma lactate to pyruvate in the glutamate dehydrogenase-deficient patients. Decreased glutamate catabolism may result in an excess of glutamate in the nervous system and cause neuronal degeneration.

Monosodium glutamate kinetic studies in human volunteers

(a) A kinetic study of plasma glutamic acid (GA) was made after monosodium glutamate (MSG) administration to human volunteers. MSG was given at doses of 30,60 and 120 mg/kg in a bouillon and of 60 mg/kg in tomato juice. In another experiment a normal meal was consumed without added MSG. (2) Plasma area under the curve (AUC) was found to be lower in females than in males. (3) Plasma AUC was lower when MSG was taken in tomato juice than when consumed in bouillon. (4) Consumption of the normal meal did not result in any significant increase in plasma GA.

Plasma glutamic acid levels in premature newborn

24 premature, newborn infants were investigated for plasma glutamic acid (GA) levels before and after a normal milk feed, to ascertain if the ingestion of GA present in the milk could result in an increase of its plasma level. No increases were detected in plasma between 5 and 90 min after the feed. These results may be important in respect to the problem of the possible toxicity of monosodium glutamate (MSG) added to baby foods.