Now, for the nuance doctors want you to understand. Onions are remarkably safe for most people, but they aren’t for everyone—and more isn’t always better.
1. Digestive Sensitivity
Onions are high in fermentable oligosaccharides (FODMAPs) . For individuals with irritable bowel syndrome (IBS) , small intestinal bacterial overgrowth (SIBO), or other functional gut disorders, onions can trigger:
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Bloating and distension
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Excessive gas
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Abdominal pain
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Altered bowel habits
What to do: If you have diagnosed IBS, work with a dietitian to determine your personal tolerance level. Some people can tolerate small amounts of cooked onion better than raw; others may need to avoid onions entirely during flare-ups.
2. Acid Reflux and Heartburn
Onions, particularly raw ones, can relax the lower esophageal sphincter, allowing stomach acid to splash upward. They may also delay gastric emptying, increasing pressure on the sphincter.
What to do: If you’re prone to reflux, try cooking onions thoroughly—this reduces their pungency and may make them better tolerated. Pay attention to your personal triggers.