Some eight months ago, I reproduced these effects in myself by drinking a hot water solution of something called "Better Than Bouillon". I put about a teaspoon into a mug of hot water. On one mug per day, I was okay, but if I drank three per day, I got the headaches.
The listed ingredients of this paste are: roasted beef with concentrated beef stock, salt, hydrolyzed soy protein, sugar, corn syrup solids, flavour (dried onion and garlic, spice extracts), dried whey (milk), potato flour, caramel, corn oil, xanthan gum.
Must be the dried onion? :)
I've consumed beef, salt, corn syrup, onion, garlic, spices, whey powder, caramel, corn oil in the past in much larger amounts. Xanthan gum is just a thickener; I've used it! No problems. The only thing that stands out there is the "hydrolyzed soy protein".