Summary
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What is olive leaf extract?
The leaves of olive trees contain a variety of compounds, with the predominant one being oleuropein, which is not found in significant concentration in the olive fruit. Dried olive leaf is about 6% oleuropein, while extracts (the most common form in supplements) provide about 1% to 40% oleuropein (see What It Is). -
What are the health benefits of olive leaf extract?
Some evidence suggests that olive leaf extract can slightly lower elevated blood pressure and cholesterol levels. Preliminary research suggests that olive leaf extract may have a modest benefit in people with type 2 diabetes, help retain bone density, and shorten the duration of colds (but not prevent them). Used topically, it may speed the healing of cold sores (see What It Does). 
Which is the best olive leaf extract supplement?
ConsumerLab's tests showed that the selected products contained their expected amounts of oleuropein (and several provided more) and passed purity testing for heavy metals. However, claimed amounts of oleuropein per serving ranged about 3-fold across the products (from 36 to 100 mg), so a consumer needs to factor this in when choosing an olive leaf extract product (see What CL Found).
Among the products Approved in our tests, we found that one, sold as capsules, provided superior value, providing oleuropein at just ¼ the price or less of other products. It was chosen as ConsumerLab's overall Top Pick for olive leaf extract. For people who prefer a liquid, we selected a Top Pick liquid olive leaf extract that also offers good value and other important attributes.-
What is a typical dose of olive leaf extract?
As described in the What It Does section, clinical trials have used various extracts providing 100 to 136.2 mg oleuropein daily from products standardized to about 1% to 40% oleuropein. That means to get a dose of 100 mg of oleuropein, you would need 250 mg of a 40% extract, 500 mg of a 20% extract, or 1,000 mg (one gram or about 1 mL if a liquid) of a very low-concentration (1%) extract. That is, the higher the % oleuropein, the less extract you need, so be sure to check this on labels. -
Is olive leaf extract safe?
Olive leaf extract appears to be generally safe and well-tolerated based on small clinical trials, although gastrointestinal symptoms can occur. It should be used with caution in people with hypoglycemia, diabetes, or those taking blood sugar lowering medications. Allergic reactions can occur, particularly among people who are sensitive or allergic to olive pollen or the pollen of related plants. For more details, see Concerns and Cautions.
