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:

  • Bloating and distension

  • Excessive gas

  • Abdominal pain

  • 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.

3. Blood Sugar Considerations

While onions are low-glycemic and generally beneficial for blood sugar, some people experience reactive hypoglycemia after consuming them. This is uncommon but worth noting if you notice shakiness or fatigue after meals rich in onions.

What to do: Pair onions with protein, fat, and fiber to blunt any potential blood sugar response.

4. Blood Thinning Interactions

Onions contain small amounts of vitamin K and have mild antiplatelet effects. For most people, this is a benefit. However, if you take high-dose warfarin (Coumadin) or other blood thinners, dramatically increasing your onion intake could theoretically affect your INR levels.

What to do: You don’t need to avoid onions. Just be consistent. Don’t go from eating them rarely to eating massive amounts daily without informing your doctor and monitoring your levels.

How to Eat Onions Daily: Practical, Delicious Strategies

The goal isn’t to choke down raw onions you dislike. It’s to incorporate them in ways that feel natural and enjoyable.

Breakfast:

  • Sautéed onions and bell peppers folded into scrambled eggs

  • Thinly sliced scallions on avocado toast

  • Caramelized onions on a breakfast sandwich

Lunch:

  • Grated red onion in tuna or chicken salad

  • Pickled red onions on sandwiches and grain bowls

  • Thinly sliced raw onion in salads

Dinner: