Do you enjoy adding onions to most meals? It’s a good habit to have, but it’s important to watch your portions. Eating excessive amounts of onion can upset your gut, among other potential side effects. As with everything, moderation is key.
This vegetable is a nutritional powerhouse, offering substantial doses of antioxidants. Fresh yellow onions provide approximately 270 to 1,187 milligrams of flavonols per kilogram, according to a 2007 review featured in the Journal of Agricultural and Food Chemistry. The same amount of red onions contains 415 to 1,917 milligrams of flavonols, a type of flavonoid. These nutrients may decrease inflammatory markers, protect against cancer, and bolster immune function, as per a 2021 review published in Pharmaceutical Biology. Furthermore, consuming onions may lower your risk of vascular and heart disease, enhance eye health, and maintain cognitive sharpness, note the study authors.
However, too much of anything can be detrimental — and onions are no exception. This vegetable can cause bad breath and body odor, disrupt digestion, and trigger allergies.
Onions may affect digestive health
Some people experience bloating and gas after eating onions, and there’s a reason for that. These veggies are high in fructans, a group of carbohydrates that can ferment in the digestive system and are not well absorbed in the small intestine (via Eat This, Not That!). Consequently, they may cause stomach pain, cramps, and other gastrointestinal issues, especially in individuals with irritable bowel syndrome. Both raw and cooked onions contain fructans, but simmering them in oil may help reduce side effects.
This vegetable may also trigger heartburn, suggests a 2000 review published in the journal Nutrition and Cancer. The same is true for tomatoes, chocolate, garlic, and citrus fruits. These foods can cause the lower esophageal sphincter to relax, allowing gastric acid to flow back into the esophagus. Cooked onions are less likely to cause issues, but they should still be consumed in moderation. Try a small amount, observe how your body reacts, and adjust your portions accordingly.
Beyond that, onions are generally safe for most people. Eating too much onion may temporarily cause bad breath, but this effect typically fades within hours, according to Healthline. There’s also a risk of allergic reactions, notes Medical News Today. In such cases, you might experience nausea, diarrhea, hives, difficulty breathing, itching, and other symptoms within two hours of eating onions, regardless of the quantity consumed.
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