The nice thing above Melissa O'Brien's above paper is that, a serious pharmaceutical researcher, she takes it for granted that MSG causing headaches is real. Like there is no question any more.

It's a tour de force. A nice highlight in the paper is when she explains how she thinned the skull bones of rats, in order to directly observe the change in flow in brain blood vessels caused by glutamate, without the disruption of actually drilling through the bone. A real life Amy Farrah Fowler, man! :)

Most of the prior MSG research was largely conducted by shills hired to defend the food industry. They made serious mistakes like: instead of randomly sampling, specifically recruiting people with self-reported sensitivities: that's a good way to gather a motley crue of tin-foil-hat hypochondriacs. If you recruit that way, then for every person with an actual sensitivity, you will get 100 others who just feed on mass hysterias. And those people will predictably claim that they have a headache from a placebo. It's a ploy designed to lump the real sufferers into the same group as a bunch of flakes and make them the object of ridicule. Another pattern is the blatant dismissal of edge results. Oh, only 3 more people had headaches on the real thing than the placebo out of a whopping hundred. That's just noise! Yes, fuck the several people who are actually sensitive to CGRP and/or have that genetic feature that makes them slow to clear glutamate (discussed above paper).