What Happens to Your Body If You Eat Raw Onions Every Day?

November 3, 2025 •

3 min read

According to a 2019 review, eating more anthocyanin-rich foods like red onions is associated with a lower risk of heart disease. So, what happens to your body if you eat raw onions every day? The regular consumption of raw onions can provide significant antioxidant, anti-inflammatory, and prebiotic benefits, but it is not without potential drawbacks, especially for sensitive individuals.

Quick Summary

This article explores the health impacts of daily raw onion consumption, detailing the numerous benefits like improved heart health, boosted immunity, and better digestion, alongside the potential negative effects such as bloating, heartburn, and bad breath. It provides a balanced overview of what to expect when integrating raw onions regularly into your diet.

Key Points

Enhanced Heart Health: Daily raw onion consumption can lower blood pressure, reduce cholesterol, and help prevent blood clots due to sulfur compounds and quercetin.
Improved Gut Health: Raw onions contain prebiotics like inulin that nourish beneficial gut bacteria, promoting a healthier digestive system.
Potent Anti-inflammatory Effects: The high antioxidant content helps combat chronic inflammation and oxidative stress throughout the body.
Potential Digestive Discomfort: For sensitive individuals, especially those with IBS, raw onions can cause gas, bloating, and heartburn.
Stronger Immune System: High levels of Vitamin C and antioxidants work to boost the body's immune function and ward off infections.
Bad Breath and Body Odor: The sulfur compounds responsible for the pungent aroma can cause temporary bad breath and body odor after consumption.
High Antioxidant Retention: Raw onions preserve more of their heat-sensitive compounds compared to their cooked counterparts.

A Daily Dose of Antioxidants and Anti-Inflammatories

Onions are members of the Allium genus, which also includes garlic and leeks. When eaten raw, they are a nutrient-dense food packed with antioxidants and sulfur-containing compounds. Regular consumption of raw onions floods the body with powerful plant compounds that combat oxidative stress and chronic inflammation, two major drivers of disease. Yellow and red varieties contain especially high levels of flavonoids like quercetin, with one study showing yellow onions having nearly 11 times more antioxidants than white ones. The quercetin content, which may even increase with light cooking, is a potent anti-inflammatory that helps neutralize harmful free radicals.

Benefits for Cardiovascular and Immune Health

Raw onions offer specific advantages for both the heart and immune system. Their sulfur compounds and quercetin work together to promote heart health by helping to lower blood pressure, reduce cholesterol, and prevent blood clots. Research has indicated that regular onion intake can lower the risk of cardiovascular events. For the immune system, the high vitamin C content and potent antioxidants support white blood cell production, acting as a line of defense against infections. Quercetin has also shown promising antiviral properties.

Supporting a Healthy Gut Microbiome

One of the most notable effects of eating raw onions daily is the impact on digestive health. Raw onions are a rich source of prebiotics, such as inulin and fructooligosaccharides (FOS). These non-digestible fibers serve as food for beneficial gut bacteria, promoting the growth of a healthy microbiome. A thriving gut environment is linked to improved nutrient absorption, better mood, and a stronger immune system. The fiber content also helps regulate bowel movements and prevent constipation.

Potential Drawbacks and Side Effects

Despite the many benefits, daily consumption of raw onions can cause issues for some people. The same compounds that make them so healthy, like fructans, can be difficult to digest for individuals with conditions like Irritable Bowel Syndrome (IBS), leading to gas, bloating, and abdominal discomfort. Raw onions are also a well-known trigger for heartburn, as they can relax the lower esophageal sphincter, allowing stomach acid to flow back into the esophagus. The high sulfur content is responsible for causing bad breath and, in some cases, a lingering body odor. Additionally, while rare, some individuals may have an onion allergy, experiencing symptoms ranging from skin rashes to anaphylaxis.

Raw vs. Cooked Onions: A Comparison


Feature	Raw Onions	Cooked Onions
Nutrient Retention	Higher levels of sulfur compounds and Vitamin C, which can be heat-sensitive.	Some loss of heat-sensitive vitamins and enzymes.
Antioxidant Levels	High in quercetin and other flavonoids, though some research suggests cooking may increase bioavailability.	Potentially higher levels of bioavailable quercetin, especially with light heating methods.
Digestibility	Can cause digestive upset, gas, and heartburn due to potent fructans and sulfur compounds.	Often easier on the stomach, as cooking breaks down some of the hard-to-digest fibers.
Flavor Profile	Pungent, sharp, and spicy flavor.	Mellow, sweeter, and more caramelized flavor.
Best Culinary Uses	Salads, sandwiches, salsas, and as a garnish.	Soups, stews, sauces, sautés, and roasted dishes.

How to Minimize Discomfort from Raw Onions

For those who experience digestive issues, there are ways to mitigate the effects without giving up raw onions entirely. Soaking sliced raw onions in water for at least 15 minutes can reduce some of the compounds that cause discomfort. Reducing portion sizes and pairing onions with other foods can also help. Chewing gum or rinsing your mouth with a mix of water and lemon juice immediately after can help combat bad breath.

Conclusion: Balancing Benefits and Risks

Incorporating raw onions into your daily diet can offer impressive health benefits, particularly for heart and gut health, due to their rich antioxidant, anti-inflammatory, and prebiotic properties. However, it is essential to be aware of the potential side effects, such as digestive distress, heartburn, and bad breath. Listening to your body is key. For many, a small daily portion is well-tolerated and highly beneficial, while for others with sensitivities, moderation or preferring cooked varieties may be a better strategy. By understanding the unique effects of eating raw onions every day, you can make an informed decision to optimize your health and well-being.

Authoritative Outbound Link

For more detailed scientific studies on the bioactive compounds in onions and other Allium vegetables, see this extensive review from the National Institutes of Health: Allium cepa: a treasure of bioactive phytochemicals with prospective health benefits.

Frequently Asked Questions

Yes, for some individuals, especially those with sensitive digestive systems or IBS, the fructans (a type of prebiotic fiber) and sulfur compounds in raw onions can cause gas, bloating, stomach pain, and heartburn.

Both are healthy, but red and yellow onions typically have higher levels of health-promoting antioxidants like quercetin compared to white onions. Red onions also contain anthocyanins, which offer additional antioxidant benefits.

Yes, some studies suggest that compounds in onions, such as quercetin and sulfur compounds, can help regulate blood sugar levels by improving how the body processes glucose and responds to insulin.

You can try soaking sliced onions in water for at least 15 minutes before eating to reduce some of the gas-causing compounds. Reducing your portion size, chewing thoroughly, and pairing them with other foods can also help.

Both are beneficial, but their advantages differ. Raw onions retain more heat-sensitive vitamins and enzymes, including some sulfur compounds. Cooked onions, on the other hand, can be easier to digest and may have higher levels of bioavailable quercetin.

The sulfur compounds released when you chew raw onions are responsible for its pungent aroma. These compounds can be absorbed into the bloodstream and later released through the lungs (causing bad breath) and skin pores (causing body odor).

While rare, it is possible to have an allergic reaction or intolerance to onions. Symptoms can include skin rashes, eye irritation, nausea, or, in severe cases, breathing difficulties.