How much maximum onion one can eat in day without any side effects?

Onions are Food: Onions are food, not medicine. There would be no 'side effects' to report. I do not believe there is any science on this subject: 'how many onions are too many onions?". Onions are sugar or carbohydrate calories. There is very little of nutritious value in onions.

Can't give specific: Amt. Onions are nutritious. They are high in flavonoids, vit c, vit b6, chromium, dietary fiber ; sulfuric compounds. Studies have shown that onion to reduce Insulin resistance ; improve tolerance to glucose. They can help maintain healthy bones w osteoporosis. Excessive onion intake in pregnant women ; people with heartburn can ^ heartburn symptoms.

Variable effects: Different people have different tolerances for foods like onions, even though they're very nutritious (as per dr. Fowler)! eat them ; you'll be getting lots of flavonoids including quercetin that help your immune system http://tinyurl.Com/kfpegph several servings a week can decrease risk of cancer. To specifically decrease oral ; esophageal cancer risk, eat 1/2 cup/day in some form. Bon appetit!