Which Onion is Best for Anti-Inflammatory Properties?

January 9, 2026 •

4 min read

Studies have shown that all varieties of onions contain powerful antioxidants and compounds that combat inflammation. But when it comes to maximizing these health benefits, the answer to which onion is best for anti-inflammatory properties depends on the type, the part of the onion, and how it is prepared.

Quick Summary

Red onions, shallots, and yellow onions are rich in the flavonoid quercetin, which has significant anti-inflammatory effects. Red varieties contain additional antioxidants called anthocyanins. The outermost layers and raw consumption maximize the anti-inflammatory compound content, though cooking can also be beneficial.

Key Points

Red onions are top-tier: Red varieties are highest in both quercetin and anthocyanins, two potent anti-inflammatory antioxidants, especially when eaten raw.
Shallots are a concentrate: These smaller onions are rich in quercetin and can be more bioavailable from certain parts, making them a powerful anti-inflammatory choice.
Cooking affects nutrients differently: Eating onions raw preserves heat-sensitive vitamins, while cooking can increase the bioavailability of other beneficial polyphenols.
Don't over-peel: Much of an onion's quercetin is in its outer layers, so avoid discarding too much of the bulb's thick, fleshy layers.
Choose organic when possible: Studies have indicated that organic red onions may contain higher levels of key antioxidants compared to their conventionally grown counterparts.
Variety is key: To receive a broad range of anti-inflammatory compounds, incorporate different types of onions—red, yellow, white, shallots, and green—into your diet.

The Anti-Inflammatory Power of Onions

Onions belong to the Allium genus, a family of vegetables celebrated not only for their distinctive flavor but also for their potent health-promoting properties. The key to their anti-inflammatory power lies in two main groups of compounds: flavonoids, particularly quercetin, and organosulfur compounds. These antioxidants work by neutralizing free radicals and inhibiting inflammatory responses within the body. Incorporating various types of onions into your diet can be a delicious and effective strategy for supporting your overall health and combating chronic inflammation.

A Comparison of Onion Varieties for Anti-Inflammatory Effects

Different onions offer varying levels of anti-inflammatory compounds. While all are beneficial, some have a clear advantage depending on the specific antioxidant profile you are looking for.

The Red Onion Advantage

Red onions are widely regarded as one of the top choices for fighting inflammation. Their vibrant, reddish-purple color is a result of anthocyanins, a powerful group of antioxidants also found in berries and red wine. These compounds, in combination with high levels of quercetin, provide a strong anti-inflammatory and disease-protective effect. Red onions are often consumed raw in salads, which helps preserve their beneficial properties since heat can degrade some of these nutrients.

The Mighty Shallot

Often overlooked, shallots pack a powerful punch in a small package. These smaller, sweeter cousins of the onion are also rich in anti-inflammatory compounds, including quercetin. Research has shown that shallots contain a significant concentration of quercetin, and certain parts, like the dry skin, may offer a particularly high bioavailability. This makes them an excellent addition to salad dressings, sauces, and lighter dishes where their delicate flavor can shine.

The Versatile Yellow and White Onions

Yellow onions, the workhorse of many kitchens, are a robust source of anti-inflammatory sulfur compounds. While they contain less quercetin than red onions, studies suggest that cooking them, especially with methods like sauteing or baking, can increase the bioavailability of their beneficial polyphenols. White onions tend to be milder and lower in flavonoids compared to red or yellow varieties, but they still provide valuable nutrients and are particularly suited for raw consumption in salsas and Mexican cuisine.

The Nutrient-Rich Green Onion

Green onions, or scallions, provide a milder flavor and are a good source of vitamins, including Vitamin C, which is another crucial antioxidant. They contain a mix of flavonoids and organosulfur compounds that contribute to their anti-inflammatory effects. Since they are typically eaten raw or only lightly cooked, they retain a higher concentration of heat-sensitive vitamins compared to cooked, mature onions.

The Impact of Cooking on Anti-Inflammatory Compounds

The preparation method is a key factor in maximizing the anti-inflammatory benefits of onions. While cooking can make some nutrients more bioavailable, it can also degrade others.

Raw is best for heat-sensitive compounds: Eating raw red or green onions, such as in salads or sandwiches, preserves the full content of heat-sensitive flavonoids and vitamin C.
Lightly cooked is a good compromise: Sautéing or lightly cooking onions can improve the availability of certain polyphenols while retaining many benefits. This process is ideal for yellow and white onions.
Don't discard the outer layers: The outermost layers of an onion are particularly rich in quercetin. By not over-peeling, you can increase your intake of these beneficial compounds.
Utilize the liquid: When boiling or simmering onions for soups and stews, much of the quercetin can leach into the cooking liquid. This makes the broth a rich source of dietary flavonoids.

Which Onion is Best for Anti-Inflammatory Purposes?


Onion Variety	Key Anti-Inflammatory Compounds	Best For	Best Preparation	Notes
Red Onion	Highest in Quercetin & Anthocyanins	Raw dishes, salads, sandwiches	Raw	Excellent for maximum antioxidant intake.
Shallot	High in Quercetin	Sauces, dressings, light sautés	Raw, Lightly Cooked	Potent anti-inflammatory properties, with some of the highest bioavailability from the skin.
Yellow Onion	Rich in Sulfur Compounds & Quercetin	Cooking bases, caramelized dishes	Cooked	Cooking can increase the bioavailability of polyphenols.
White Onion	Rich in Prebiotic Fiber	Salsas, raw garnishes	Raw, lightly cooked	Milder flavor, less potent antioxidant profile than red onions.
Green Onion (Scallion)	Vitamins C, Flavonoids, Organosulfur Compounds	Garnishes, salads, stir-fries	Raw, Lightly Cooked	Good source of Vitamin C; used for milder flavor.

Conclusion: Mix and Match for Maximum Benefit

Ultimately, the best strategy for maximizing anti-inflammatory benefits is to consume a variety of onions and prepare them in different ways. Red onions and shallots are top contenders for raw preparations, offering high levels of quercetin and anthocyanins. Meanwhile, yellow onions are excellent for cooked dishes, as heat can enhance the availability of their antioxidant compounds. Green onions provide a milder flavor and a dose of Vitamin C when added fresh to meals. By incorporating a colorful mix of these alliums into your diet, you can enjoy a wide spectrum of anti-inflammatory properties that support overall health.

Frequently Asked Questions

Raw onions retain more heat-sensitive nutrients like vitamin C and certain sulfur compounds. However, light cooking can increase the bioavailability of other polyphenols, like quercetin, by breaking down the plant's cell walls. For a mix of benefits, incorporate both raw and lightly cooked onions into your meals.

Red onions contain the highest levels of the flavonoid quercetin and are also rich in anthocyanins, the pigments that give them their red color. These compounds work together to provide powerful antioxidant and anti-inflammatory benefits.

Yes, all common onion varieties contain quercetin, but in varying concentrations. Red, yellow, and shallots typically have higher levels, while white onions have the least.

Yes, the dry outer skin and outermost fleshy layers of an onion are particularly concentrated with quercetin. These can be tied in a cheesecloth and added to stocks or broths to infuse the liquid with beneficial compounds.

Onions are a good source of prebiotic fiber, specifically fructans, which nourish beneficial gut bacteria. This can improve overall gut health and reduce inflammation.

Yes. While some volatile compounds may be lost during the caramelization process, the process can also make other anti-inflammatory polyphenols more bioavailable. Caramelized onions still offer significant antioxidant benefits.

Quercetin is a powerful flavonoid antioxidant found in onions. It reduces inflammation by neutralizing free radicals that cause cellular damage and by blocking the release of pro-inflammatory compounds in the body.