The present invention relates to a pharmaceutical or veterinary or nutritional or personal care composition comprising coenzyme Q.sub.10 (CoQ.sub.10), reduced CoQ.sub.10, or mixtures thereof and oxygenated dibenzo-.alpha.-pyrone or an amino acyl ester thereof. The composition of the present invention is able to support and/or provide therapy to individuals at risk and/or under treatment for dysfunctions of energy metabolism, and specifically, for mitochondrial diseases.