Is red onion good for your lungs? A detailed health analysis

December 25, 2025 •

3 min read

According to a study published in the journal Nutrients, allium vegetables like onions and garlic can significantly reduce the incidence of respiratory tract infections in elderly volunteers. This growing body of research highlights the promising link between these bulbs and lung function, leading many to question: is red onion good for your lungs, and how can it support respiratory wellness?

Quick Summary

This article explores the nutritional compounds in red onions, like quercetin and organosulfur compounds, and their anti-inflammatory, antioxidant, and antimicrobial effects that may benefit lung function and respiratory health. It also reviews scientific findings, practical consumption methods, and important considerations for supporting your lungs through diet.

Key Points

Rich in Antioxidants: Red onions are packed with powerful flavonoids, especially quercetin, which act as potent antioxidants that protect lung cells from oxidative damage.
Fights Inflammation: Quercetin has demonstrated anti-inflammatory properties in studies, helping to reduce airway inflammation associated with conditions like asthma and COPD.
Antimicrobial Support: The organosulfur compounds in onions offer antimicrobial effects that can help the body fight off respiratory infections from bacteria and viruses.
Natural Expectorant: Onions have been used traditionally as a remedy to help loosen and expel mucus from the respiratory system, easing chest congestion.
Promotes Healthy Airways: Research indicates that compounds in onions may help protect the lining of the lungs and bronchial tubes against damage from environmental pollutants.
Enhances Immune Function: The vitamin C and other nutrients in red onions help boost the immune system, providing better defense against respiratory illnesses.

The Anti-Inflammatory and Antioxidant Power of Red Onions

Red onions contain vitamins, minerals, and bioactive compounds that contribute to their potential health benefits for the respiratory system. They are particularly rich in flavonoids, a type of antioxidant, including a significant amount of quercetin. These compounds help protect cells from damage caused by free radicals.

The Role of Quercetin in Lung Health

Quercetin supports lung function through its anti-inflammatory and antioxidant effects. Studies have shown that quercetin can reduce oxidative stress and inflammation in animal models of COPD. It has also been observed to improve lung elasticity and decrease the activity of enzymes that degrade lung tissue in these studies. In vitro research suggests quercetin may help in the regeneration of airway lining cells, which are often damaged in COPD patients. Furthermore, quercetin may offer protection against lung damage from pollution.

Organosulfur Compounds and Antimicrobial Effects

Organosulfur compounds in onions, similar to those found in garlic, contribute to their distinctive smell and health properties. These compounds have shown antimicrobial activity against various pathogens, which may help the body fight off respiratory infections.

A Natural Expectorant for Congestion

Onions have a long history as a traditional remedy for coughs and colds. Their sulfuric compounds are believed to act as a natural expectorant, helping to loosen and clear mucus from the lungs and chest, potentially easing congestion during respiratory illnesses.

Comparison: Red Onion vs. Other Varieties for Respiratory Benefits

All onions offer health benefits, but red onions stand out due to their high content of anthocyanins, which give them their color, and higher levels of quercetin compared to white onions.


Feature	Red Onion	White Onion	Yellow Onion
Quercetin Content	High; often noted as having twice as much as white onions.	Lower than red onions.	Good source, but generally less than red onions.
Anthocyanins	High; the pigments are powerful antioxidants linked to reduced heart disease risk.	Absent	Absent
Flavor	Sharper, slightly spicier when raw; milder when cooked.	Pungent when raw; mellows significantly when cooked.	Strong, pungent flavor that sweetens with cooking.
Respiratory Potential	Potentially higher due to concentrated antioxidants and flavonoids.	Beneficial but possibly less potent than red.	Beneficial due to flavonoid content.

Incorporating Red Onions into a Lung-Supportive Diet

To best utilize red onions for lung health, consider these methods:

Raw: Adding raw red onion to salads and sandwiches helps preserve its high concentration of beneficial compounds like quercetin.
Onion Syrup: A traditional remedy, made by layering sliced onions with honey, is thought to help soothe coughs and clear mucus.
Soups and Broths: Including onions in warm liquids can provide comfort and potentially help loosen mucus during illness.
Cooked: While cooking reduces some nutrients, sautéed or roasted onions still provide antioxidants and anti-inflammatory benefits.

Important Considerations

Red onions are a supportive dietary element and should not replace medical treatment for respiratory conditions. It is essential to follow a doctor's advice for conditions like asthma or COPD. Some individuals may experience digestive issues due to the fructan content in onions. The body's absorption of compounds like quercetin can be complex. The effects of red onion compounds in everyday situations are still being explored and should be considered as a complementary dietary choice rather than a cure. You can read more about the scientific basis of these benefits in the article, Beneficial Effects of Daily Consumption of Garlic and Onion Extract.

Conclusion: Can Red Onions Benefit Your Lungs?

Evidence suggests that the quercetin and other flavonoids in red onions can offer benefits for lung health. Their antioxidant, anti-inflammatory, and antimicrobial properties may help reduce inflammation in the airways, protect against damage, and support the immune system against respiratory infections. While not a cure for lung diseases, including red onions in a balanced diet can be a helpful way to support respiratory health, especially during cold and flu season. This aligns with traditional knowledge about the health benefits of onions.

Frequently Asked Questions

No, while compounds in red onion show potential in reducing inflammation associated with asthma and COPD in studies, it is not a cure. Patients with chronic lung conditions should always follow a doctor's medical advice.

Yes, consuming red onion raw or lightly cooked preserves the highest concentration of beneficial compounds like quercetin and anthocyanins. Cooking can reduce some of these antioxidants, though cooked onions still offer health benefits.

Red onions contain sulfur compounds with expectorant properties, which help to thin and loosen mucus in the chest and throat. This can make it easier to clear congestion during a cold or infection.

For most people, red onions are safe to eat in moderation. However, in large amounts, they can cause digestive upset, bloating, or heartburn in some individuals, particularly those sensitive to fructans.

Onion poultices are a traditional home remedy believed to help with chest congestion by improving circulation and loosening mucus. While anecdotal evidence exists, it is not a medically proven cure, and you should consult a doctor for serious infections.

Both red onions and garlic are allium vegetables rich in beneficial compounds. While red onions contain high levels of quercetin, garlic is a potent source of allicin. A combination of both extracts has been shown to reduce respiratory infections.

A higher intake of flavonoids, including those in onions, has been linked to a lower risk of developing COPD, particularly in smokers. Quercetin has also shown promise in animal studies for improving lung function after exposure to cigarette smoke. However, this does not negate the primary benefits of quitting smoking.