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Researchers from the University of Auckland have determined that olive leaf extract has the ability to decrease insulin resistance and increase the production of insulin by the pancreas.
In this randomized, double-blinded and placebo-controlled clinical study, the researchers divided 46 overweight men into two groups. They gave one group olive leaf extract (standardized to oleuropein and hydroxytyrosol) and the other group a placebo for twelve weeks. The placebo and olive leaf extracts were both given in capsules and their identity completed masked.
Then after a six-week washout period, the researchers switched the groups, giving the placebo group the extract and the olive extract group the placebo.
The researchers found that the olive leaf extract lowered insulin resistance by an average of 15% and increased the productivity of the pancreas' beta cells – which produce insulin - by 28%.
Insulin sensitivity was measured using a glucose tolerance test, which measures glucose and insulin levels in the blood every thirty minutes. pancreatic beta cell function was measured using the Matsuda method of glucose/insulin curve measurements.
The researchers concluded:
"Supplementation with olive leaf polyphenols for 12 weeks significantly improved insulin sensitivity and pancreatic β-cell secretory capacity in overweight middle-aged men at risk of developing the metabolic syndrome."
While the research shows the ability of olive leaf to treat type 2 diabetes, this effect of olive leaf extract upon the pancreas' beta cells means that olive leaf may well be able to treat or partly ameliorate type 1 diabetes outcomes – related to an insufficiency and relative destruction among the beta cells that depletes their ability to produce enough insulin.
In their analysis of this study together with other research on olive leaf surmised that the effects upon a person with type 2 diabetes would likely be more pronounced. This concept is confirmed by a number of studies of conventional medications that showed effects upon diabetics are greater than on non-diabetic individuals.
The scientists, in their comparison to conventional drugs for insulin sensitivity, noted that the olive leaf extract's effects of increasing beta cell production at the same time as increasing insulin sensitivity was unique, because the conventional medications typically produce the effect of increasing beta cell activity but not affecting insulin sensitivity.
"Hence, compared to these drugs that only improve insulin secretion, olive leaf extract improves both insulin sensitivity and pancreatic β-cell secretory capacity. Remarkably, the observed effects of olive leaf extract supplementation in our study population is comparable to common diabetic therapeutics (particularly metformin)..."
The ability of olive leaf extract to treat type 2 diabetes was confirmed in a study last year from Israeli medical researchers. In this study, 79 type 2-diabetic patients were given 500 milligrams daily olive leaf extract or a placebo for 14 weeks. The olive leaf treatment group had significantly lower levels of HbA1c (glycosylated hemoglobin) and lower fasting plasma insulin levels.
de Bock M, Derraik JG, Brennan CM, Biggs JB, Morgan PE, Hodgkinson SC, Hofman PL, Cutfield WS. Olive (Olea europaea L.) leaf polyphenols improve insulin sensitivity in middle-aged overweight men: a randomized, placebo-controlled, crossover trial. PLoS One. 2013;8(3):e57622.
Wainstein J, Ganz T, Boaz M, Bar Dayan Y, Dolev E, Kerem Z, Madar Z. Olive leaf extract as a hypoglycemic agent in both human diabetic subjects and in rats. J Med Food. 2012 Jul;15(7):605-10. doi: 10.1089/jmf.2011.0243.