June 2013

Document Type


Degree Name



Dept. of Public Health and Preventive Medicine


Oregon Health & Science University


In recent years, obesity has become a significant worldwide problem, and has been shown to be associated with chronic diseases such as diabetes, hypertension, and cancer. The mechanisms by which obesity is linked to these diseases are not fully understood. Studies have shown that conjugated linoleic acid (CLA) is effective at reducing obesity and preventing cancer in mice, and that it increases lean body mass in humans. Furthermore, research has linked inflammation, oxidative stress, and increased activity of oxidative stress response genes to cancer. In this randomized clinical trial, we examine a possible link between CLA and both oxidative stress and inflammation. I examined forty-eight healthy, obese individuals for twelve weeks to assess the effects of three different doses of CLA (placebo, 3.2 g/day, and 6.4 g/day) on several factors. These factors include DNA damage due to oxidative stress, expression of the oxidative stress response genes Nrf2 and SOD1, serum C-reactive protein (CRP) levels, and serum interleukin-6 (IL-6) levels. I used Comet assays to measure DNA damage, Real-Time Polymerase Chain Reactions to measure Nrf2 expression and SOD1 expression, and clinical laboratory analyses to measure serum CRP levels and serum IL-6 levels. Increases in CLA dosage were significantly associated with increases in CRP levels (p = 0.007) and IL-6 levels (p = 0.02). Age confounded the association among CLA dose and IL-6 levels, but not CRP levels. In conclusion, we found that supplementation with CLA for twelve weeks increases the levels of CRP in obese, but otherwise healthy individuals, but further research needs to be conducted to assess the mechanism by which CLA affects inflammation, and subsequently, obesity.




School of Medicine



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