Wide-ranging claims have been made for the effectiveness of onions against conditions ranging from the common cold to heart disease, diabetes, osteoporosis, and other diseases.[8] They contain chemical compounds believed to have anti-inflammatory, anticholesterol, anticancer, and antioxidant properties such as quercetin. However, it has not been conclusively demonstrated that increased consumption of onions is directly linked to health benefits. Some studies have shown that increased consumption of onions reduces the risk of head and neck cancers.[9] In India some sects do not eat onion due to its alleged aphrodisiac properties.[10]
In many parts of the world, onions are used to heal blisters and boils. A traditional Maltese remedy for sea urchin wounds is to tie half a baked onion to the afflicted area overnight. In the United States, products that contain onion extract are used in the treatment of topical scars; some studies have found their action to be ineffective,[11][12][13] while others found that they may act as an anti-inflammatory or bacteriostatic[14] and can improve collagen organization in rabbits.[15]
Onions may be especially beneficial for women,[16] who are at increased risk for osteoporosis as they go through menopause, by destroying osteoclasts so that they do not break down bone.
An American chemist has stated[17] that the pleiomeric chemicals in onions have the potential to alleviate or prevent sore throat.