A process for improving the health of a subject, the process comprising orally administering a composition comprising hydroxytyrosol to the subject to provide the subject with a daily dose of about 0.1 to about 750 μg hydroxytyrosol per kg of body weight, and a dietary supplement in dosage unit form for oral administration, the dosage unit form comprising a composition containing about 1 microgram to about 50 milligrams hydroxytyrosol or an ester or salt thereof.