I love salad, but it doesn't ever seem to settle right. Anyone else?

My husband had this problem before his surgery. He had GERD and even though he loved salads, he couldn't eat them. So, you aren't alone.

My husband told me for years that whenever he are iceberg lettuce he'd get heartburn or an upset stomach and I thought he was crazy because I'd never heard of it before. However, I've since heard of many others with the same problem and he also can eat Romain with not problem. So it's obviously something with the iceberg, but I don't know what. Annie