The Effects of Low-Fat Diet and Exercise on C-Reactive Protein and Metabolic Syndrome: Findings from a Randomized Controlled Trial

Background: Low-fat diet (D) and exercise (E) are recommended for reducing cardiovascular disease risk. However, the independent and combined effects of D and E on C-reactive protein (CRP) and metabolic syndrome (MS) are unknown. Purpose: The purpose of this dissertation was to examine the changes in CRP and MS between control (C), D, E and diet plus exercise (D+E). Methods: Men (n=197) and postmenopausal women (n=180) with elevated low-density lipoprotein cholesterol and reduced high-density lipoprotein cholesterol, were randomized into a one-year trial with four groups: C, D, E or D+E (Stefanick et al., 1998). Weight loss was not an intervention focus. This secondary data analysis evaluated stored plasma samples for high-sensitivity CRP. MS prevalence was retrospectively found using the NCEP-ATP III definition. CRP change (ΔCRP) was examined between intervention groups using ANCOVA. Differences between groups for MS at follow-up were retrospectively investigated using logistic regression. All analyses were stratified by gender and controlled for baseline values, body fat change and other appropriate covariates. Results: In women, ΔCRP was different between D+E vs. C (-0.7 ± 0.33 mg/L, p = 0.04) and D+E vs. E (-0.9 ± 0.32 mg/L, p = 0.004). Women also had a decrease in CRP within D+E (Δ log CRP 0.2 ± 0.035 mg/L; p = 0.0002). After the intervention, ΔCRP did not differ for men between or within treatment groups. MS at follow-up was not different between C, D, E or D+E in either men or women. In women with MS, ΔCRP was different between D+E vs. C (-1.3 ± 0.43 mg/L; p = 0.006), D+E vs. E (-1.1 ± 0.44 mg/L; p = 0.02), and D vs. C (-1.2 ± 0.43 mg/L; p = 0.009). In women with MS, CRP decreased from baseline within D+E (Δ log CRP 0.2 ± 0.039 mg/L; p=0.0008). At follow-up, there were no differences between or within groups for ΔCRP in men with MS, or men without MS and women without MS. Conclusion: D and D+E may be effective treatments for reducing CRP in women with MS. Further studies are needed to replicate results and clarify the influence of gender