Although it is best known as a vegetable, Allium cepa--or the common onion--has also been used as an alternative treatment for numerous health issues since ancient times. Onion has been used to treat respiratory illnesses, such as the common cold, cough, bronchitis, and asthma. It also has been utilized for relieving gas and calming an upset stomach. Onion juice can be used on the skin for treating wounds, insect stings, warts, and skin blemishes, as well as for stimulating hair growth. It is also believed that onion can decrease swelling, lower cholesterol, and even reduce blood sugar (glucose) levels.
Taj Eldin, Ahmed, and Elwahab H.M. in Sudan decided to study the effects of red onion in both type 1 and type 2 diabetics. Type 1 diabetes is an autoimmune disorder in which the pancreas produces little to no insulin, a hormone that regulates blood glucose levels. Type 2 diabetes is a metabolic disorder in which the pancreas produces insulin, but the body is not able to properly respond to it. Both types of diabetes result in high blood glucose levels, known as hyperglycemia.
The researchers recruited type 1 and type 2 diabetics who were under the age of 50, had the illness for two to five years, did not have any other diseases or diabetic complications, and did not use supplements, alcohol, or cigarettes. Type 1 diabetics were split into two groups. The first group had fasting blood glucose measured, whereas the second group received 75 mg of glucose at baseline in order to measure glucose tolerance. Each group was further subdivided into three more groups: a negative control group receiving 5 ml of water, a positive control group receiving 5 IU/prescribed dose of the standard treatment of insulin, and a test group receiving 100 mg of fresh red onion. Fasting blood glucose levels and glucose tolerance were measured at baseline, one, two, and four hours. This same procedure was applied to type 2 diabetics, except the positive control group received 5 mg of the standard treatment of glibenclamide.
Taj Eldin et al. found that at the end of four hours red onion significantly reduced fasting blood glucose levels and induced hyperglycemia (result of the glucose tolerance test) in both type 1 and type 2 diabetics. However, the standard treatments of insulin and glibenclamide were even more successful at reducing fasting blood glucose levels in both type 1 and type 2 diabetics and induced hyperglycemia in type 1 diabetics than red onion. The researchers acknowledged that it was difficult to reach a concrete conclusion because of small sample sizes. Nonetheless, they suggested that red onion’s hypoglycemic effects could be beneficial in the management of type 1 and type 2 diabetes.
1. Davidson T, Frey RJ. Allium Cepa. Healthline. 2005. Available at http://www.healthline.com/galecontent/allium-cepa/2.
2. Taj Eldin IM, Ahmed EM, Elwahab H.M. A. Preliminary study of the clinical hypoglycemic effects of Allium cepa (red onion) in type 1 and type 2 diabetic patients. Environ Health Insights. 2010;4.