Olive leaves have been used in medicine nearly as long as olive branches have been symbols of peace: for roughly 5,000 years. The leaf is the only medicinal part of the olive tree, native to the Mediterranean but now grown in temperate climates all over the world.
Uses: Olive leaves are used in efforts to manage high blood pressure and high blood sugar.
Dose: Doses vary, but most range from 200 to 500 milligrams taken one to four times a day in capsule form. Dried olive leaves can be used to make a medicinal tea; the recommended dose is 3 to 4 cups daily, using 2 teaspoons of dried leaves per cup.
Precautions: People with diabetes should exercise caution when using olive leaf supplements; high doses could cause blood sugar levels to fall dangerously low. People on drugs to lower blood pressure -- including ACE inhibitors, beta blockers and calcium channel blockers -- should check with their doctors before taking the supplements to avoid harmful drug interactions.
Research: Lab and animal studies show that olive leaf extracts can lower blood sugar and blood pressure and decrease the risk of developing high blood pressure. Research suggests that the responsible compound, a chemical called oleuropein, dilates blood vessels and prevents them from hardening. Lab experiments also suggest that olive leaf extracts may be able to fight off fungal, viral and bacterial infections. The few human studies of olive leaf extract have been small and inconclusive.