I have been told that things like mushrooms and tomatoes and seaweed are all high in msg.

I love tomatoes, I eat a lot of them, I eat a lot of mushrooms, I roast things like cauliflower and Brussels sprouts just to intensify their umami - garlic, does garlic have a lot of msg in it, idk but I eat that too.

The thing people have trouble with is the synthesised msg.  I might be in a small category by having a near death experience on contact but I have noticed how most people right in that flush of enjoyment of the food with the msg enhancing it have gone red faced and a bit sweaty or gone grey faced and a bit sweaty.

None of that happens after eating fried tomatoes on toast.  It's all happy.  Peace and harmony reign.