There are so many beauty terms that it can make your head spin. Confused as to what it all means? Our Glam Glossary will help you sort it all out. Follow Allison each week in her quest to decode popular beauty terms, from Alpha Hydroxy Acids to Zinc Oxide.

Quercetin

What it is: Quercetin is one of the most abundant naturally occurring flavonoids, or bioflavonoids, and it’s found in most herbs, fruits and vegetables — including apples, onions, red wine and green tea.

Where you see it: Anti aging treatments.

What it does: An apple a day should keep the wrinkles at bay. Among its various health benefits, quercetin is an antioxidant, which means it helps fight against free radicals. It’s noted for having anti-inflammatory properties, promoting cellular function and is also considered very unlikely to irritate sensitive skin when applied topically. This compound is found in so many of the fruits and veggies we’re recommended to eat every day , and its health benefits aren’t restricted to topical solutions: You can receive the skin care benefits of quercetin by eating healthy, not just by applying creams.

The American Cancer Society notes that while there’s no substantial clinical evidence that quercetin can prevent or treat cancer in humans, early lab reports appear promising.

Photos: Laura Mercier (cover); Korres