Monosodium Glutamate (MSG) Renders Alkalinizing Properties and Its Urinary Metabolic Markers of MSG Consumption in Rats.

Nahok Nahok,Cha’on Cha’On,Abdul Abdul,Thanan Thanan,Phetcharaburanin Phetcharaburanin,Wongkham Wongkham,Selmi Selmi,Silsirivanit Silsirivanit,Li Li,Anutrakulchai Anutrakulchai

doi:10.3390/biom9100542

Abstract

Monosodium glutamate (MSG) is widely used as a flavor enhancer and its effects on human health are still debated. We aimed to investigate whether MSG can act as alkalinizing agent in murine models and if its metabolites are biomarkers of MSG consumption. For this purpose, adult male Wistar rats were given water added with 1 g% MSG or three types of control water, including sodium chloride (NaCl) and sodium bicarbonate (NaHCO3). At 14 days, urinary pH, electrolytes, urinary metabolites and ion-exchanger gene expression were determined. The results revealed that MSG-treated rats had significantly more alkaline urine and higher levels of urinary sodium and bicarbonate similar to NaHCO3 controls. These changes correlated with a lower expression of ion-exchanger genes, namely, CAII, NBC1, and AE1, which are involved in bicarbonate kidney reabsorption. The urinary metabolic profiles also revealed similar patterns for the MSG and NaHCO3 groups. In conclusion, MSG exhibits similar properties to NaHCO3, an alkalinizing agent, with regard to inducing alkaline urine, reducing bicarbonate kidney reabsorption, and generating a specific urinary metabolic pattern. We believe that these observations will be useful to further study the MSG effects in humans.

Highlights

Monosodium glutamate (MSG) is commercially produced as a flavor enhancer in processed foods and home cooking and its use is exponentially increasing worldwide [1]
Urine analyses indicated that the MSG and NaHCO3 treatment groups had significantly higher urine pH compared to controls
Urinary Na+ was significantly higher in MSG, NaCl, and NaHCO3 -treated rats compared to controls (3.1 ± 0.17, 4.59 ± 0.31, 8.84 ± 1.12, 1.28 ± 0.05 mEq/day, respectively)

Summary

Introduction

Monosodium glutamate (MSG) is commercially produced as a flavor enhancer in processed foods and home cooking and its use is exponentially increasing worldwide [1]. Cross-sectional and longitudinal studies from our group and others have revealed that the consumption of MSG is associated with human metabolic syndrome [3], obesity [4,5], and arterial hypertension [6], conflicting evidence is available [7,8]. MSG causes alkaline urine in rats following long-term consumption [14]. Urine alkalinization using available alkalinizing agents such as potassium citrate (K citrate) [15,16] and sodium bicarbonate (NaHCO3 ) [17,18]

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Conclusion