Development and Validation of an Inflammatory Index

Chronic inflammation is associated with a number of chronic conditions, such as cancer, cardiovascular disease, obesity, insulin resistance, depression, and dementia. The ability to decrease levels of inflammation may help prevent or treat these conditions. Diet has consistently been shown to modulate inflammation. We sought to develop and validate an Inflammatory Index (II), designed to assess the inflammatory potential of an individual's diet. The II was developed based on results of an extensive literature search. Using data from the SEASONS study, a longitudinal trial that carefully measured diet and the inflammatory marker C-reactive protein (CRP), analyses was carried out to determine the association between CRP and II score. Important potential confounders of the diet-CRP association were controlled in the analytic models. Results based on continuous measures of CRP suggested that increasing II score (representing movement towards an anti-inflammatory diet) was associated with a decrease in CRP. We performed additional analysis using CRP as a dichotomous variable using a CRP value of 3mg/L as a cutoff point and found that an anti-inflammatory diet along the continuum of the II was associated with a significant decrease in the odds of an elevated CRP. Results provide construct validation of the II and additional evidence that diet plays a role in the regulation of inflammation, even after careful control of a wide variety of potential confounders. Also, results provide evidence for one of the mechanisms in which dietary factors may decrease the risk of cancer, cardiovascular disease and other inflammatory related conditions.