Chinese Restaurant Syndrome is a disorder caused by the presence of MSG (Monosodium Glutamate) in food causing several symptoms including headaches, skin flushing, sweating etc. The syndrome is also named as MSG symptom complex.
MSG is a sodium salt of glutamic acid and it is the most naturally occurring non-essential amino acid. It is usually an odorless, white monohydrate that is available in crystalline powder form. MSG contains separate glutamate anions and sodium cations.
It dissociates into sodium and glutamate in solution form. It is freely soluble in water and in organic solvents it is considered as insoluble. Like other amino acids MSG does not break down during cooking because it is generally stable under food processing conditions. Hence its effects cannot be demoted by cooking.
Toxicity of MSG:
Chinese Restaurant Syndrome caused by MSG has various other syndromes including obesity, neurotoxicity, metabolic disorders and damaging effects on the reproductive system. Studied revealed that even the small dose of MSG is toxic to health and 0.3-1.0 g of MSG is estimated dose per day is average intake.
Symptoms of Chinese Restaurant Syndrome
Symptoms can also be observed via intravenous 50mg dose of MSG. The neonatal consumption of MSG leads to adverse effect on the behavior, insulin resistance and glucose tolerance. The leading obesity develops due to disturbance in the signaling cascade of lipid-mediated hypothalamus and due to umami flavoring to food.
The expression in the visceral adipose tissue of micro-RNA of interleukin-6, resistin, tumor necrosis factor-alpha and leptin is triggered by MSG. This ultimately result in the impaired tolerance of glucose by increment in the concentration of resistin, insulin and leptin.
The MSG presence leads to hepatic damage by reduction in the concentration of liver transaminase. In patients having steatohepatitis, the liver inflammation lasts longer. The patients suffering from Chinese Restaurant syndrome feel burning sensation at the back of neck, fatigues, general weakness, blistering on arms, dizziness and facial pressure usually 20 minutes after consumption of MSG.
The reproductive system of both males and females is affected by MSG and leads to changes in the gustatory and metabolic effects. In some cases, angioedema of uvula can be fatal after the ingestion of MSG in food if it is not timely treated. Additionally, there are abundant reports of harmful effects such as oxidative stress, DNA damage, protein modification and lysis of stromal cells.
Confirmation of toxicity of MSG through researches
The syndrome results due to the release of metabolites of glutamate after the ingestion of MSG containing food. The MSG in the food acts on the receptors of glutamate present in amygdala, hippocampus and hypothalamus where they are involving in controlling metabolic activities.
They release neurotransmitters which lead to pathological pathway. The uptake of MSG is facilitated by high-affinity glutamate transporters through the blood-brain barrier. Research conducted on cortical neurons of mouse showed that during the incubation of cells in MSG, the cells went through swelling leading to injury which might be related to the cause of headaches after MSG consumption.
It was also found that the immature cortical neurons upon incubation with MSG were resistant and were thus not susceptible to injury. This might be due to absence of receptors involved in binding of MSG or due to downstream signaling pathways for MSG in immature cells. Hence, young children with more immature neurons do not experience headaches after consuming MSG.
MSG affects the reproductive system by disrupting cellular-hypertrophy of the follicles in ovaries. MSG studied on human models indicated that its consumption and haemoglobin levels have a positive relation to each other. This might be due to leptin’s important role in the process of haematopoiesis.