Are the associations between diet and C-reactive protein independent of obesity?

OBJECTIVES: To determine the relative magnitude of the effect of dietary factors on circulating C-reactive protein (CRP) levels, controlling for BMI.

METHODS: 1808 men and 2269 women attended the 1994/95 follow-up survey from the Busselton Health Study, Australia. A composite diet score was derived from a short questionnaire. Height and weight were measured.

RESULTS: After controlling for BMI, CRP levels were associated with red meat intake (males only, p=0.001), fruit intake (males p<0.0001, females p=0.029), potato intake (males p=0.008, females p=0.029), using wholemeal bread (males p=0.014, females p=0.018), using polyunsaturated fats as a spread and in cooking (females only, p=0.005), and rarely or never adding salt to food (males p=0.012, females p=0.004). The overall diet score was significantly (negatively) related to CRP in males (p<0.0001) and females (p<0.0001). The relative decrease in CRP from a moderately healthy diet, compared to an unhealthy diet was 37% in men and 24% in women. This was comparable to a difference in BMI of at least 3 kg/m(2) (or a difference in weight of approximately 9 kg for a person of average height).

CONCLUSION: A healthy diet and lower weight have independent beneficial effects of similar magnitude on CRP levels.