Re: Why do onions cause heartburn?
It's interesting that GERD is exacerbated by two factors - extra acidity and relaxing of the LES. Looks like onions do the latter:
Onions, chocolate, and mints:
Onions, chocolate, and mints have all been shown to cause indigestion by relaxing the LES.17-21, The effects of onion on acid reflux and reflux symptoms were investigated in 16 normal subjects and 16 heartburn subjects.17 Subjects were studied by testing the acid in their esophagus two hours after the ingestion of a plain hamburger and a glass of ice water. The identical meal, with the addition of a slice of onion, was ingested on another day. Onions significantly increased all measures of heartburn in subjects and were found to be a potent and long-lasting cause of reflux in heartburn patients. Cooking onions destroys substances that are the cause of indigestion. This is why most people have no problems with cooked onions.