Glutamate: A Safe Nutrient, Not Just a Simple Additive

Abstract

Background: In 2017, an European Food Safety Authority (EFSA) opinion on the use of glutamate and its salts as food additives led to an ADI of 30mg/kg body weight/day. Then, in 2021, an EFSA statement presented a proposal for harmonising the establishment of Health-Based Guidance Values for nutrients that are also regulated substances (including food additives). The present review argues that the 2017 glutamate ADI is unsuitable because safety of glutamate should firstly consider its status as a nutrient and not only as an additive. Summary: Glutamate is a non-essential amino acid playing a key role in nitrogen homeostasis. The dietary exposure to glutamate in adults is extensive, due to its ubiquitous presence in foods, under three forms: bound to proteins, naturally free and free form added as an additive. Glutamate naturally included into proteins is the major source of dietary glutamate. Thus, since it plays a role in nitrogen homeostasis, it is a nutrient before being an additive. Its pharmacokinetics is largely impacted by concomitant food intake but the extent to which plasma glutamate concentration must rise to have deleterious effects is never encountered in humans consuming glutamate in their daily diets. This is due to the fact that glutamate is highly metabolized in the splanchnic area. Key Messages: Glutamate should be considered as a safe nutrient before as an additive by risk assessor.

Time-resolved concentrations of serum amino acids, one-carbon metabolites and B-vitamin biomarkers during the postprandial and fasting state: the Postprandial Metabolism in Healthy Young Adults (PoMet) Study

“…Intriguingly, the most abundant amino acids in the high-energy breakfast were leucine, glutamic acid and proline, indicating that the amino acid postprandial response cannot entirely be explained by the abundance of the amino acids eaten. Further, glutamic acid is one of the most abundant amino acids found in dietary protein (28) , but in the present study, we observed only small changes in glutamic acid after the meal compared with most other amino acids, which has also been observed by others (29) . It has been suggested that glutamic acid is metabolised to various amino acids in the enterocyte, mainly alanine but also proline (28) , which may explain the observations in the present study.…”

Glutamic‐acid grafted hyaluronic acid inhibits inflammatory factors via fibroblast and skin model tests

“…This results in ATP synthesis and elevated mitochondrial ATP levels. 21,22 Additionally, the studies by Carole 16,23 demonstrated that HA derivatives, such as amino acid derivatives, can effectively decelerate HA degradation. This allows HA to persist in the extracellular matrix and sustain receptor binding for an extended period.…”

“…At the same time, CD44 is involved in cellular uptake of hyaluronan, promoting endocytosis of HA‐Glu into the cell plasma. The internalized HA‐Glu is cleaved by hydrolases within the cell cytoplasm, resulting in the release of glutamate that subsequently generates glutathione (GSH) to maintain redox balance and alleviate oxidative stress 21 . Hydrolases may also cleave the grafting glutamate site into glutamine, which then migrates into the mitochondria to perform its function.…”

“…This process includes deamination catalysis by Glutaminase (GLS), followed by the conversion to a TCA cycle intermediate via glutamate dehydrogenase (GDH). This results in ATP synthesis and elevated mitochondrial ATP levels 21,22 …”

Glutamate and obesity – what is the link?

“…However, these concerns were invalidated, as numerous studies reporting adverse health effects used a parenteral administration route and/or relied on doses far exceeding the typical levels consumed in food products. Current reports on its dietary consumption do not seem to raise safety concerns [24,25].…”