Study says onion lowers blood sugar but then why are so many Indians diabetic still?

According to The Independent, the findings were presented at The Endocrine Society’s 97th annual meeting in San Diego on August 25 and revealed that the extract of an onion bulb could “strongly lower” high blood sugar and total cholesterol levels when given alongside the anti-diabetic drug Metformin. The lead study author, Anthony Ojieh of Delta State University, in Abraka, Nigeria, was quoted as saying, “Onion is cheap and available and has been used as a nutritional supplement. It has the potential for use in treating patients with diabetes.” Of course, it must be noted that the researchers tested the theory on rats. In total, three groups of rats with medically induced diabetes were given various doses of the onion extract to see if it would enhance the drug’s effect.

Questioning the study, Dr Anoop Misra, Chairman, Fortis CDOC Center for Diabetes, says, “Going by this logic, India wouldn’t have been the diabetes hotspot it is today. We consume a lot of onions, they are a kitchen staple and still we have so many people with diabetes. Yes, onions have a high fibre value but in India it is had in all forms, raw, as ringlets, munched down whole and used liberally in our cooking. So, till we get details about the mechanism by which the onion extract brought about the blood glucose reduction, its impact on metabolism and whether its efficacy is as good with other drugs, it will be too hasty to draw specific conclusions. We do not yet have an explanation and researchers have to work on it.”

However, he feels that “These interesting findings in rats cannot be ignored totally and the study should be replicated in humans through clinical trials. And that too it must be tested separately on Indians who have traditionally lived on onions.”

The study found that of the diabetic rats, those given 400 mg and 600 mg per kg of body weight “strongly reduced” their blood sugar levels by 50 per cent and 35 per cent respectively compared with a baseline level. The onion extract also lowered the total cholesterol level in diabetic rats, with the 400 mg and 600 mg having the greatest effects.

Finding these observations “interesting”, Dr Ambrish Mithal, Chairman and Head, Endocrinology and Diabetes, Max Healthcare, points to the massive amount of onions used, something that is difficult to internalise through a dietary route, even by humans. “They used up to 600 mg per kg of body weight in rats with induced diabetes. Only then did it result in a significant reduction in blood glucose levels. This finding is not new in the sense that there have been some isolated human case reports. But there has been no real clinical data derived from a proper study on humans,” he says.

Dr Mithal also questioned the rationale and mechanism of the study. “We can only assume that the onion-induced reduction of blood glucose levels is because of quercetin, a flavonoid, which has been found to give onions a therapeutic potential in reducing inflammation, lowering blood pressure and maintaining blood sugar. Quercetin reduces sugar as it enhances uptake of glucose by cells and improves insulin secretion. It has a long-term antioxidant property, so it protects patients from developing vascular complications. But then quercetin has to be identified as the differentiator. Without identifying the causative factor, the study is still in the realm of theory. Also, if quercetin is indeed identified in later studies, then the amount needed by a human body can only be administered as an extract in a pill. Of course, only time will tell whether this will work. We need significant and human-tested research for that,” he adds.