Do you know, I don't really remember...
I didn't get it as a daily thing, but I did have fairly regular occasions of it.
I remember trying mixing grains for porridge, and Red River cereal which I had often as a child. From that, back in the early 1990's I had acid reflux, usually by noon on the days we had it for breakfast.
I heard that some grains were thought to give this problem, so I gave up the mixture and suffered no more, though I still ate bread, pasta, rice, and occasionally some dry cereals.
I was never much of a meat-eater, but I had been eating a little more of it for, say, one year. And, always, plenty of vegetables, both cooked and raw.
I ate Cell Tech's algae around that time, and was very pleased with the results.
I think I gave up, mainly, whole wheat, whole rye, and oatmeal cereals, sugar, almost all tomato sauce, most tomatoes, prepared salad dressings (mayo, later), and processed oils (marg, etc.).
I also went for unprocessed
Sea Salt .
Does that help?
Probably you'd want to try leaving out one or two similar things at a time, then take them back and go on to try removing another item or two, until you find what is biting you back.
Hope you find it soon!
fledgling