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Researchers from China's State Agriculture Ministry and Zhejiang University have determined that two ingredients commonly found in many citrus fruits, naringin and neohesperidin, will effectively reduce blood sugar.
The study tested the two citrus constituents using human liver cells. The scientists found that the two natural compounds increase the uptake of glucose among the cells.
This study confirms previous research that pointed to the possibility that these citrus constituents may be helpful for reduce blood sugar for those with or at risk for type 2 diabetes and suffer from poor glucose control and/or heightened glucose tolerance. Other research has found these compounds also regulate liver enzymes phosphoenolpyruvate carboxykinase and glucose-6-phosphatase - helping glucose uptake regulation and increasing liver efficiency.
The researchers extracted the two flavonoids from the Chinese citrus fruit called Huyou (Citrus changshanensis). This citrus, as well as others such as Grapefruit and related species - has been used as an anti-diabetic agent in Traditional Chinese Medicine, Ayurveda and other traditional Asian medicines.
The naringin and neohesperidin compounds were found throughout the fruit part of the citrus, including the juice sacs and the segments. Another Chinese study found that the Huyou peel contained the highest naringin and neohesperidin content.
Several other citrus fruits contain naringin and neohesperidin. This doesn't mean that orange juice necessarily contains naringin and neohesperidin. A 2000 study from the Citrus Research and Education Center tested a number of orange juices using liquid chromatography. The analysis found that the two 100% orange juice samples tested contained neither naringin nor neohesperidin. However, juice samples that contained orange juice together with small amounts of grapefruit juice, sour orange (Citrus aurantium) juice and K-Early citrus juice did contain naringin and neohesperidin.
Other research has determined that the common sweet orange (Citrus sinensis) will typically contain naringin, but very small amounts, and will typically not contain neohesperidin. Sour oranges (Citrus aurantium) - especially when picked early, will contain considerable amounts of naringin and neohesperidin. Mandarin oranges (Citrus Reticulata) are also good sources for both naringin and neohesperidin. Grapefruit contains naringin and neohesperidin, but its neohesperidin content is typically smaller.
Lemons and limes typically do not contain either compound in lieu of their hesperidin content, but a few species - such as the Bergamot - will contain naringin and possibly small amounts of neohesperidin.
In addition to its anti-diabetic properties, naringen has been found in laboratory studies to be neuro-protective. It appears to protect against the effects of 3-nitropropionic acid, which has been found to be one of the primary agents that produce nerve damage in Huntington's disease and other nerve disorders.
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