The present invention relates to methods for detecting a oxidative stress in a biological sample, methods of determining a cumulative record of oxidative injury, and methods of diagnosing diseases of aging, such as cardiovascular diseases, based on the presence or absence of a biomarker or a component thereof. The present invention also relates to a kit for detecting oxidative stress in a biological sample comprising a stabilizing reactant and an antibody. In some embodiments of the invention, the biomarker of oxidative stress is selected from an aldehyde-protein adduct and an aldehyde metabolite-protein adduct, and the proposed method further comprises measuring separately for the same protein biomarkers of oxydative stress formed with different amino acids of the protein.