Grapefruit Antioxidant Could Fight Type 2 Diabetes

Kathleen Blanchard's picture
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Scientists report that grapefruit suppements could become a mainstay for treating type 2 diabetes. The antioxidant Naringenin, found in grapefruit and other citrus fruits, might increase insulin sensitivity and breakdown fat. The fruit could treat abnormal cholesterol levels, fight metabolic syndrome and improve glucose tolerance, all of which are associated with diabetes.

"It is a process which is similar to the Atkins diet, without many of the side effects," says Martin L. Yarmush, MD, PhD, director of the MGH Center for Engineering in Medicine and one of the paper's authors.

Grapefruit Targets Fats in the Liver

Naringenin, the antioxidant in grapefruit, breaksdown fatty acids in the liver instead of carbohydrate, much the same as occurs during fasting. Yaakov Nahmias, PhD, of the Hebrew University of Jerusalem the paper's senior author says, "It is a fascinating find. The results are similar to those induced by long periods of fasting".

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The action of the grapefruit supplement could potentially lower the production of bad cholesterol known known as vLDL, in addition to treating some of the symptoms of type 2 diabetes.

LXRα is a receptor in the liver involved in maintaining balance of fatty acids or lipids in addition to controlling inflammation. Sugars activate LXRa after eating, leading to the creation of fats that are stored in the liver. Fasting stimulates the relase of a different receptor, called PPARα during which fatty acids are broken down into ketones. A related process increases insulin sensitivity. Grapefruit breaks down fatty acids in the same way the body does during fasting.

Nahmias says, ""Dual PPARα and PPARγ agonists, like naringenin, were long sought after by the pharmaceutical industry, but their development was plagued by safety concerns. Remarkably, Naringenin is a dietary supplement with a clear safety record. Evidence suggests it might actually protect the liver from damage."

The grapefruit compound has been found in earlier studies to lower cholesterol and help with diabetes symptoms. The new study shows Naringenen from the citrus fruit blocks the activation of LXRα and activates PPARα and PPARγ to increase the oxidation of fatty acids in the liver. The grapefruit antioxidant slows down the production of vDL cholesterol, and appears to mimic the action of the pharmaceutical drugs Fenofibrate that lowers lipd levels and Rosiglitazone, an anti-diabetic medication.

Goldwasser J, Cohen PY, Yang E, Balaguer P, Yarmush ML, et al. (2010) Transcriptional Regulation of Human and Rat Hepatic Lipid Metabolism by the Grapefruit Flavonoid Naringenin: Role of PPARa, PPARc and LXRa. PLoS ONE 5(8): e12399. doi:10.1371/journal.pone.0012399

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