Very interesting Don,
I usually spice my pizza's individually...lay sauce down and then pinch the spices on top of that. If using MSG, would you recommend I apply it instead of my salt and should I use the same amount in the swap?
I usually put it on after the sauce. That way it gets a chance to dissolve. You could also mix it in with the sauce, but I like sprinkling it on the pie because that way I can eyeball how much without measuring.
MSG has about 40% of the sodium of table salt, so if you are salting your pizza (I don't), you may want to cut back accordingly. When I cook with MSG, I usually use less salt or no salt at all. Excess salt is way more harmful to you body than MSG. MSG is often used as a lower sodium alternative to table salt. MSG doesn't just make the food salty, but seems to bring out flavors already in the food. If you taste MSG by itself, it actually isn't all that pleasant, but with certain foods it just makes them taste better, not just salty.
I have been experimenting with veggie-only pizzas lately because my wife and I are on a diet. The MSG really makes them taste better. I proved this last week when I forgot to put it on--We both thought that it wasn't nearly as good without the MSG.
If MSG was such a problem, our friends down under should know about it. Vegemite and Marmite are pretty much glutamate paste.