Onions are also a source of the strong antioxidant vitamin C that helps to combat the formation of free radicals known to cause cancer.
Colon cancer: High fiber intakes from all fruits and vegetables are associated with a lowered risk of colorectal cancer.
Prostate cancer: In a study published by the Journal of the National Cancer Institute, researchers used a population-based, case-controlled study to investigate the relationship between allium vegetable intake and prostate cancer. They found that men with the highest intake of allium vegetables had the lowest risk for prostate cancer.
Esophageal and stomach cancer: Frequent intake of allium vegetables has been inversely related with the risk of esophageal and stomach cancer. Several survey-based human studies have demonstrated the potential protective effects of consuming alliums, as well as reports of tumor inhibition following administration of allium compounds in experimental animals.