My wife and I were sampling this soup broth used in Japanese Shabu-shabu, sukiyaki, ramen, miso soups, etc at an Asian supermarket. She says it tastes very good, so I looked at what they used to make the soup.
I knew it! I saw a bottle of Hondashi next to the table, this stuff is loaded with MSG and often used to enhance Ramen and Udon soup. I know MSG is quite common and a lot of folks say they get headaches from it but I don't think they know where MSG is often used and never heard anyone complain they got a headache from eating ramen. And it's hard to pick out MSG from a broth with pork fats because MSG is extracted from meats.
Here's a link below to Hondashi on Amazon.
https://www.amazon.com/Japanese-Dash.../dp/B000FL1OOA This stuff tastes great and it is loaded with MSG.