Investigation into the relationship between Physical Activity and Homocysteine

Abstract

Background: A beneficial effect of physical activity on the risk of cancer at several sites has been consistently observed. Biologic mechanisms that may underlie this relationship are not well understood. A potential mechanism explaining this relationship for some cancer sites is the influence of physical activity on methionine-homocysteine biosynthesis. High levels of total plasma homocysteine concentration (tHcy) indicate a breakdown in this biochemical process. This cycle’s influences on DNA methylation and endogeneous agents involved in oxidative stress are potential mechanisms linking methionine-homocysteine biosynthesis to cancer risk. This research is nested within a larger cross sectional study of healthy volunteers recruited from centers in Ontario and Nova Scotia aimed at understanding modifiable risk factors for cancer.

Purpose: This research sought to elucidate the relationship between physical activity and tHcy level.

Methods: The target population was healthy male and female subjects aged 20-50. Participants donate a 12ml blood sample after an overnight fast for analysis of tHcy and dietary factors and complete a questionnaire including a physical activity profile for the past month (adapted from the International Physical Activity Questionnaire [IPAQ]) and established predictors of tHcy level such as coffee and alcohol consumption. Multiple linear regression is used to model the relationship between tHcy and physical activity measures while controlling for potential confounders.

Results: Analysis on 171 participants has been carried out. Mean tHcy for five quintiles of physical activity (from lowest physical activity score to highest) were found to be 8.40μmol/L (7.76-9.05), 8.60μmol/L (8.00, 9.22), 9.24μmol/L (8.66, 9.81), 8.23 μmol/L(7.64, 8.82), and 8.70μmol/L (8.09, 9.31).

Conclusions: The findings of this research do not support a relationship between physical activity and total plasma homocysteine concentration. Results of this study suggest that homocysteine is not a mediating factor for the relationship observed between physical activity and cancer.