Body mass index and oxidative DNA damage: a longitudinal study

Abstract

Leanness has been shown to be related to an increased risk of some cancer forms, including lung cancer. However, biological evidence supporting a causal link between leanness and carcinogenesis is limited. The authors investigated longitudinally the association between body mass index (BMI) and levels of urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, using data from 174 healthy employees who participated in a lifestyle intervention study. 8-OHdG levels were measured using automated high-performance liquid chromatography and adjusted for urinary creatinine levels. Analysis of repeated measurements using a random effects model detected a statistically significant inverse association between BMI and 8-OHdG levels (P = 0.003); one unit decrease in BMI was associated with a 2.7% (95% confidence interval 0.9-4.4) increase in 8-OHdG levels. The association was pronounced among men consuming less than 20 cigarettes per day (8.8% increase per unit decrease in BMI) and among non-smoking men (3.7% increase). The results based on a longitudinal observation suggest that weight loss is associated with increased oxidative DNA damage, a state presumably related to an increased risk of cancer.

Figure 1

Scatterplots of percentage change in 8‐hydroxydeoxyguanosine (8‐OHdG) against percentage change in body mass index (BMI) between the baseline and 12‐month surveys. Percentage change was calculated as the difference between the values at baseline and the 12‐month survey divided by the baseline value; minus indicates decrease, whereas plus indicates increase. Data for all of the study subjects (n = 174) are plotted. The curve shows the prediction for the change in 8‐OHdG (%) based on estimation of a fractional polynomial of the change in BMI (%) by a model with two power terms.