The onion (Allium cepa), a staple bulb in global cuisine, is also a powerful ally for eye health, although its connection to vision is often incorrectly reduced to its ability to cause tearing. This irritating effect, caused by the release of thiopropanal sulfoxide gas when cut, is temporary. The true benefits for the eyes come from its rich internal nutritional profile, which offers long-term protection against the main causes of visual impairment.
Benefits of Onions for Eye Health
High Concentration of Antioxidants: Quercetin and Sulfur. Onions, especially red and purple varieties, are one of the richest sources of quercetin, a flavonoid with potent antioxidant and anti-inflammatory properties. This compound helps protect the delicate cells of the retina and lens from oxidative damage caused by free radicals, a key factor in the development of cataracts and age-related macular degeneration (AMD). Sulfur compounds (thiosulfinates) also contribute to cellular antioxidant defense.
Source of Organic Sulfur and Selenium. Sulfur is essential for the production of glutathione, considered the body’s “master antioxidant.” Adequate glutathione levels are crucial for maintaining the transparency of the lens. Selenium, present in onions, is a mineral that works synergistically with vitamin E to protect the cell membranes of the eye.
