Circadian variations in plasma and erythrocyte concentrations of glutamate, glutamine, and alanine in men on a diet without and with added monosodium glutamate

Tsai, Po Jung; Huang, Po Chao

doi:10.1016/s0026-0495(99)90159-2

Cited by 41 publications

(27 citation statements)

References 14 publications

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“…Plasma GLU concentrations are typically 50-100 mmol/l under normal conditions (Tsai and Huang, 1999;Fernstrom et al, 1996) and do not rise significantly even in the presence of sizable oral doses of MSG (Tsai and Huang, 1999). Plasma GLU concentrations appear to rise only when pharmacologic doses of MSG are administered.…”

Section: Central Nervous Systemmentioning

confidence: 99%

“…These transporters presumably would still function in situations in which BBB permeability has increased; (2) Glial and neuronal GLU transporters (Goldsmith, 2000;Meldrum, 2000) would also presumably remain functional under conditions of increased BBB permeability (except if the brain is ischemic, and thus oxygen deprived, such as during a stroke/vascular occlusion or under conditions of increased intracranial pressure), and help to keep brain ECF and basal synaptic GLU concentrations low; and (3) Dietary GLU and MSG, even at a very high dose in the daily diet (Tsai and Huang, 1999), do not raise plasma GLU concentrations (MSG intake is self-limiting, since it is not palatable at high concentrations in foods (Yamaguchi, 1987)); hence, dietary GLU or MSG should not influence synaptic GLU concentrations, per se, if BBB permeability were to be increased.…”

Section: Central Nervous Systemmentioning

confidence: 99%

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Consensus meeting: monosodium glutamate – an update

et al. 2006

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Objective: Update of the Hohenheim consensus on monosodium glutamate from 1997: Summary and evaluation of recent knowledge with respect to physiology and safety of monosodium glutamate. Design: Experts from a range of relevant disciplines received and considered a series of questions related to aspects of the topic. Setting: University of Hohenheim, Stuttgart, Germany. Method: The experts met and discussed the questions and arrived at a consensus. Conclusion: Total intake of glutamate from food in European countries is generally stable and ranged from 5 to 12 g/day (free: ca. 1 g, protein-bound: ca. 10 g, added as flavor: ca. 0.4 g). L-Glutamate (GLU) from all sources is mainly used as energy fuel in enterocytes. A maximum intake of 16.000 mg/kg body weight is regarded as safe. The general use of glutamate salts (monosodium-L-glutamate and others) as food additive can, thus, be regarded as harmless for the whole population. Even in unphysiologically high doses GLU will not trespass into fetal circulation. Further research work should, however, be done concerning the effects of high doses of a bolus supply at presence of an impaired blood brain barrier function. In situations with decreased appetite (e.g., elderly persons) palatability can be improved by low dose use of monosodium-L-glutamate.

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Section: Central Nervous Systemmentioning

confidence: 99%

Section: Central Nervous Systemmentioning

confidence: 99%

Consensus meeting: monosodium glutamate – an update

et al. 2006

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“…For this reason a nearly similar concentration of 3.0 x 10 -4 M was used for the other amino acids in the ex vivo studies. Similar in vivo investigations were carried out also in Taiwan in 1999 [1]. In this study, the circadian variations in the plasma levels of glutamate, glutamine and alanine were measured in 10 healthy men fed ordinary Taiwanese meals (included breakfast, lunch and dinner).…”

Section: Discussionmentioning

confidence: 69%

“…Plasma free amino acid concentrations have been measured for various purposes, such as to evaluate the individual's protein nutritional status, to determine amino acid requirements and circadian variations and to gain an understaning of the various metabolic aspects of amino acids [1]. Other than being components of proteins, some amino acids have individual biological or biochemical effects.…”

Section: Introductionmentioning

confidence: 99%

Effects of L-amino Acids on Human Peripheral Neutrophil Granulocyte Activation

Sipka¹,

Keresztes²,

Kovács³

et al. 2014

TONUTRJ

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Objective:The objective was to investigate the early (20 minutes) effects of 21 L-amino acids on the activation of human neutrophils and to determine in healthy individuals the effects of a meal on the 1) number and relative luminescence unit (RLU) of peripheral neutrophils, 2) serum glutamate and glucose levels and 3) mTOR signaling network. Methods:The RLU of neutrophils stimulated by Ca 2+ ionophor (CaI) and phorbol myristate acetate (PMA) following amino acid supplementation (3 x 10 -4 M) or after consuming a meal was determined. L-glutamate was measured by HPLC.Results: All amino acids resulted in significant inhibitions of neutrophil RLU, except for arginine, which stimulated neutrophils. The ratios of amino acid induced inhibition were significantly higher in the cells stimulated by PMA than by CaI. The consumption of a meal resulted in a significant serum glutamate elevation compared to baseline (2.3 versus 0.9 x10 -4 M) 90 minutes after ingestion of the meal. It was independent of the body mass index and returned near fasting levels after 150 minutes. The number of neutrophils was significantly elevated 90 minutes after the meal but the PMA induced RLU was significantly decreased. Conclusion:Our ex vivo and in vivo results suggest that the L-amino acids, independent of their metabolic significance, may continuosly and quickly modify the activity of human peripheral neutrophils, and also the outcome of various immunologic reactions. The activation of the mTORC1 complex likely involves a transient impairment in the function of mTORC2 complex in these processes.

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“…The principal conclusion from such studies is that plasma glutamate concentrations do not rise when MSG in consumed in the normal diet, even at abnormally high levels. In humans, the best study is that of Tsai and Huang (Tsai and Huang, 1999), which examined humans on 2 separate days. On 1 day, subjects ingested a normal diet [three typical meals and snacks, containing a total of about 90 g protein (see (Brosnan et al, 2014)); the baseline day].…”

mentioning

confidence: 99%

Comment on Shimada et al.: ‘Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients’

Fernstrom

2017

European Journal of Pain

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Circadian variations in plasma and erythrocyte concentrations of glutamate, glutamine, and alanine in men on a diet without and with added monosodium glutamate

Cited by 41 publications

References 14 publications

Consensus meeting: monosodium glutamate – an update

Consensus meeting: monosodium glutamate – an update

Effects of L-amino Acids on Human Peripheral Neutrophil Granulocyte Activation

Comment on Shimada et al.: ‘Increased pain and muscle glutamate concentration after single ingestion of monosodium glutamate by myofascial temporomandibular disorders patients’

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