It's the first I hear about "Chinese Restaurant Syndrome" but MSG is 12.28g per 100g sodium and so should be avoided by, or at the very least restricted in the diets of, people on a low-sodium diet, such as hypertensives, kidney patients and diabetics.
_________________
Source of the 12.28g per 100g claim:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5694874/
Which actually advocates for the use of MSG to reduce sodium, which I find very unreasonable. The point of MSG is to increase the umami taste- but you can get that from glutamate acid, without the sodium. The only extra thing you get from MSG is the extra sodium.
The article says that only a small amount of MSG is required to enhance taste, but just try asking workers in restaurants how much MSG is in the food they serve you. Try asking them how much salt is in it, even - I have a relative on a low sodium diet and I know it's pointless, people don't even understand the question. "How much salt? What do you mean?".
And of course, just because someone puts MSG in their food doesn't mean they don't also add extra salt to it. The result is that people like my relative can't eat food with MSG without getting about twice their safe daily intake from a single meal.
Another study on 1227 Chinese adults found that MSG increased blood pressure over a period of 5 years:
https://www.ncbi.nlm.nih.gov/pubmed/21372742
But I can't read the full text.