A decoction of olive leaves comprises an aqueous composition containing at least from about 500 mg/liter to about 3,000 mg/liter of oleuropein, from about 100 mg/liter to about 300 mg/liter of hydroxytyrosol, from about 90 mg/liter to about 280 mg/liter of tyrosol, from about 400 mg/liter to about 1,800 mg/liter of elenolic acid.
