Red onions offer a range of potential health benefits, including being rich in antioxidants, particularly anthocyanins. These antioxidants may help protect against chronic diseases like diabetes and certain types of cancer. Red onions are also a good source of quercetin, which may help maintain normal blood pressure and improve heart health. 
Here's a more detailed look at the benefits:
May Reduce Disease Risk:
The antioxidants in red onions may help reduce the risk of chronic diseases such as cancer and diabetes. 
Heart Health:
Onions, especially red onions, contain quercetin, which may help lower blood pressure and improve heart health. They also contain allicin, which may help reduce high blood pressure and LDL cholesterol. 
May Support Gut Health:
Onions can promote the growth of healthy gut bacteria, contributing to better digestive health. 
Other Benefits:
Red onions are also a good source of vitamin C and potassium, and they have antibacterial properties. 
Rich in Antioxidants:
Red onions are packed with antioxidants, including flavonoids like anthocyanins, which give them their vibrant color. These antioxidants help protect cells from damage caused by free radicals.