Hacker News Reader

Comment by SunShiranui | Hacker News Reader

Is there any actual evidence that MSG should be "cause for concern"?

No. None whatsoever. MSG is just the sodium salt of glutamic acid. Just like table salt breaks down into its constituent sodium and chlorine in water, MSG breaks down into sodium and glutamic acid, the latter of which is in high quantities in beef, poultry, eggs, fish, dairy, and so on.

Fear of MSG is, chemically speaking, utter nonsense.

I lost any confidence I had in the author when I saw that line.

No.

https://en.wikipedia.org/wiki/Monosodium_glutamate#Safety

Double-blinded studies have debunked the idea of MSG sensitivity. Preparations high in MSG tend to be high in sodium as well, which people are sensitive to.

Counterexample: http://www.ncbi.nlm.nih.gov/pubmed/9215242

Even if it's true about the sodium, that still leaves MSG as way to sneak lots of sodium into a meal in a form that doesn't taste salty.

Incidents of the "restaurant syndrome" might be caused by a large amount being accidentally or carelessly dumped into the food. (E.g. the perforated lid comes off the MSG container while it is shaken and the food is served anyway).

If that happened with a salt container, they would think twice before serving it anyway, due to the food obviously tasting over-salted.

There is a balance to be kept by the body between GABA and glutamate (oversimplification). The former is an inhibitory neurotransmitter, and the latter is excitatory. So - it really depends. If your nervous system is overexcited, having glutamate (doesn't matter whether from natural or lab-made sources) might be a bad idea. If you are pretty balanced or have a GABA surplus, you'll be fine.

BTW this balance does seem to play a role in autism and ADHD, and suppressing glutamate is considered as an option in this article: http://www.ncbi.nlm.nih.gov/pubmed/25666800

Current scientific evidence indicates that glutamate does not cross the blood brain barrier. While glutamate is very active in the brain, it does not appear that consumption has any effect.

Something doesn't have to cross the barrier to cause a headache or other effects. A constriction or dilation of the blood vessels in the brain will do.

What evidence is there that glutamic acid is a vasodilator?

Just found some pig and rat experiments:

http://www.ncbi.nlm.nih.gov/pubmed/2572176

"We examined the effects of topically applied amino acids (glutamate, aspartate, glycine, and taurine) and a synthetic glutamate analogue [N-methyl-D-aspartate (NMDA)] on pial arteriolar tone and cortical surface cerebrospinal fluid (CSF) dilator prostanoid concentrations in anesthetized newborn pigs. [...] We conclude that these amino acids are potent dilators of the neonatal cerebral circulation."

http://www.ncbi.nlm.nih.gov/pubmed/9134957

"Taken together, these results indicate that glutamate contributes to the dilatory tone of cerebral microvessels under physiologic conditions and that this effect is mediated by NMDA receptors. Glutamatergic vasodilation is dependent on neuronal discharge activity and the neuronal production of NO."

Experiment with glutamate infusion in cardiac surgery patients:

http://www.ncbi.nlm.nih.gov/pubmed/11724641

"These data show that an intravenous glutamate infusion after routine CABG surgery significantly improved cardiac haemodynamic performance without direct effects on cardiac substrate metabolism. This suggests that a reduction of the afterload via a peripheral vasodilatory effect is the main mechanism leading to the observed changes in haemodynamics."

Reply on news.ycombinator.com