A method is proposed that has the potential to lessen detrimental damages caused by reactive oxygen species (ROS) to proteins, nucleic acids, lipids, and other components in living cells. Typically, ROS oxidize substrates by a mechanism involving hydrogen abstraction in a rate-limiting step. The sites within these (bio)molecules susceptible to oxidation by ROS can thus be "protected " using heavier isotopes such as (2)H (D, deuterium) and (13)C (carbon-13). Ingestion of isotopically reinforced building blocks such as amino acids, lipids and components of nucleic acids and their subsequent incorporation into macromolecules would make these more stable to ROS courtesy of an isotope effect. The implications may include enhanced longevity and increased resistance to cancer and age-related diseases.