Low dietary quality and physical inactivity are well-established lifestyle risk factors for age-related chronic diseases, including cardiovascular diseases and certain cancers. One underlying mechanism that links lifestyle risk factors and subsequent chronic diseases is hyperinsulinemia. Studies suggest that hyperinsulinemia may contribute to age-related chronic diseases by increasing systemic inflammation and oxidative damage. Leukocyte mitochondrial DNA copy number reflects the number of mitochondria within each cell. As a biomarker of intracellular oxidative stress, leukocyte mitochondrial DNA copy number has been related to individual lifestyle factors, such as diet and weight. However, no epidemiologic study has examined the relationship between the combined insulinemic potential of lifestyle and leukocyte mitochondrial DNA copy number.
A new study, published in The Journal of Nutrition, examined the association between the Empirical Lifestyle Index for Hyperinsulinemia, a measure that characterizes the insulinemic potential of 3 lifestyle factors combined – diet, weight gain, and physical activity, and leukocyte mitochondrial DNA copy number. Researchers Keming Yang (Harvard T.H. Chan School of Public Health), Hongmei Nan (Indiana University Richard M. Fairbanks School of Public Health), Fred Tabung (The Ohio State University), and colleagues utilized data from 2 ongoing prospective cohorts in the United States: the Nurses’ Health Study and the Health Professionals Follow-Up Study. Lifestyle and dietary habits were assessed by mailing subjects self-administered questionnaires every 2 years. Blood samples were collected from women between 1989 and 1990 in the Nurses’ Health Study and between 1993 and 1995 in men from the Health Professionals Follow-Up Study. For this study, a total of 2,160 women from the Nurses’ Health Study and 675 men from the Health Professionals Follow-Up Study were included in the final analysis.
The study results indicate a significant inverse association between the Empirical Lifestyle Index for Hyperinsulinemia and the leukocyte mitochondrial DNA copy number. Higher hyperinsulinemic lifestyle scores were associated with lower leukocyte mitochondrial DNA copy number among subjects without major diseases, suggesting the difference in lifestyle insulinemic potential may be related to excessive oxidative stress damage. This study highlights the importance of lifestyle modification strategies as a means of preserving mitochondrial function.
Reference Yang K, Forman MR, O Monahan P, Graham BH, Chan AT, Zhang X, De Vivo I, Giovannucci EL, Tabung FK, Hongmei N. Insulinemic Potential of Lifestyle Is Inversely Associated with Leukocyte Mitochondrial DNA Copy Number in US White Adults. The Journal of Nutrition, Volume 150, Issue 8, August 2020, Pages 2156–2163, https://doi.org/10.1093/jn/nxaa146.
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