Plasma C-reactive protein concentration is not affected by isocaloric dietary fat reduction

Objective: There is a strong correlation between plasma C-reactive protein (CRP) concentration and risk of cardiovascular death. Low-fat diets have been recommended for maintenance of cardiovascular health, and it is known that a low-fat diet associated with weight loss lowers CRP concentration. However, it remains unclear whether dietary fat has an effect independent from weight change on markers of inflammation. Methods: Sixteen overweight subjects who were 46 ± 14 y old were placed on a weight-maintaining baseline diet consisting of 35% fat, 45% carbohydrate, and 20% energy as protein. After 2 wk, subjects were switched to an isocaloric low-fat diet consisting of 15% fat, 65% carbohydrate, and 20% protein for another 2 wk. For the final 12 wk of the study, subjects consumed the same 15% fat diet ad libitum. At the end of each diet phase, CRP was measured by a high-sensitivity CRP assay. Results: The weight of subjects remained stable during the first 4 wk of isocaloric diets. Plasma CRP concentrations after 2 wk on the weight-maintaining 35% fat diet and 2 wk on the isocaloric 15% fat diet were not significantly different (median ± interquartile range 1.42 ± 3.30 and 1.59 ± 3.29 mg/L, respectively). Three months of ad libitum low-fat diet consumption resulted in a 4.1 ± 0.7 kg weight loss associated with a decrease in CRP concentration to 1.17 ± 2.03 mg/L (P = 0.03). Conclusion: Loss of body weight decreases CRP concentration, but a decrease in dietary fat without a concurrent change in body weight does not affect CRP concentration in overweight healthy subjects.