What would cause heartburn in marinara sauce? So there's this pizza place in Rhode Island which makes some of the best pizza I've ever had. I tend to order the "plain" pizza, which is just sauce. It's that kind of pizza where the sauce is thick and excessive, dolloped all over on an equally thick bread, but it's extremely good sauce. That's the style.

The problem is that after eating it, I get heartburn for hours. It's bizarre, and I would eat there more often if that weren't the case but it's really rather unpleasant. I do not experience this with anything else whatsoever.

What ingredient would cause such a phenomenon, and is there a way to change it? I'm hoping I can notify them of this.

Also, is this the sort of thing that doesn't affect everyone? My father gets the same effect from their pizza, and he stopped eating there. I haven't asked anyone I'm not related to, so I don't know if it's just a genetic thing or if this is a common reaction.
Tomatoes relax the lower esophageal sphincter, a muscle at the top of the stomach that contracts to keep stomach contents from going back up the esophagus. The more concentrated the sauce the more the relaxing effect. Alcohol does this as well, and over-eating can lead to the LES muscle being unable to overcome the pressure. So if you had a big portion of pizza with extra strong tomato sauce and a few beers or glasses of wine it's a triple-whammy.