Mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism is associated with longevity in the Japanese population, and the Mt5178A genotype may confer antiatherogenic advantages. Individuals with the Mt5178A genotype may be more resistant to adult-onset diseases, such as myocardial infarction, cerebrovascular diseases and type 2 diabetes, than those with the Mt5178C genotype. Moreover, Mt5178 C/A polymorphism has been reported to be associated with blood pressure, serum lipid levels, hematological parameters, intraocular pressure, serum protein fraction levels and serum electrolyte levels in healthy Japanese individuals. Differences in the influence of habitual drinking or habitual smoking on health status between the Mt5178C genotype and the Mt5178A genotype have been reported. The individual modification of drinking habits or smoking habits based on the genotyping of Mt5178 C/A may promote improved health and lead to the establishment of personalized prevention strategies for adult-onset diseases.