In an initial randomized, double-blind, placebo-controlled study published in 2018, 29 healthy volunteers consumed 30mg of hydroxytyrosol per day for four weeks. In a 2020 study, arranged similarly, 92 volunteers took 30mg hydroxytyrosol per day for 12 weeks. Both studies have demonstrated a reduction of LDL cholesterol in the blood plasma—the first study showed reduced LDL cholesterol by 9.4mg/dL, the second showed reduced LDL cholesterol by 8.5mg/dL.