Olive leaf extract is a supplement derived from the leaves of the plant that bears olive (a fruit from which the cooking oil is derived from) and contains the main bioactives of hydroxytyrosol/tyrosol and oleuropein/ligstroside.
Olive phenolics in general, which are present in high levels in olive leaf supplements, appear to potently protect LDL cholesterol from oxidation. This is attributed to the anti-inflammatory effects of hydroxytyrosol, and appears to be active at a low enough dose to apply to consumption of olive product consumption. Olive leaf may also influence levels of lipoproteins in a beneficial manner (LDL, HDL, total cholesterol, although the actual changes in lipoprotein content is rather small. Overall, olive phenolics are more anti-artherosclerotic than they are cholesterol reducing.
There also appears to be beneficial effects on glucose metabolism, which may be related to the pancreas. The mechanisms of olive leaf and glucose metabolism are not fully elucidated at this point in time, but appear to be more of a preventative supplement than a rehabilitative one.
Although olive leaf has been implicated in fat burning through various mechanisms (increased thyroid hormones and adrenaline), trials have failed to show a fat burning effect with olive leaf supplement use. The reason for this is not known, but may be related to a decrease in levels of the receptor that adrenaline works through which may attenuate the effects.
