THE ASSOCIATION BETWEEN DIETARY INFLAMMATORY INDEX (DII) AND ODDS OF GLIOMA: A CASE-CONTROL STUDY

Background and Aim: Previous studies have shown that certain dietary components may be implicated in the etiology of glioma. However, specific attributes of the relationship between diet-related inflammation and the odds of glioma remain unclear.Methods: To investigate the role of diet-associated inflammation and glioma, we can use the Dietary Inflammatory Index (DIITM), which has been shown to predict levels of inflammatory markers in blood. DII can be used to evaluate the potential of diet-associated inflammatory effects in different populations using a variety of assessment instruments such as 24-hour recall interviews, food frequency questionnaires (FFQ) and food record. FFQ-derived dietary data used to calculate DII scores for all participants. The DII based on literature published through 2010 linking diet to inflammation. Individuals’ intakes of food parameters on which the DII based then compared to a world standard database. Briefly, to calculate DII for the participants of this study, the dietary data first linked to the regionally representative world database we constructed that provided a robust estimate of a mean and standard deviation for each parameter. These then become the multipliers to express an individual’s exposure relative to the standard global mean as a z-score. This achieved by subtracting the standard global mean from the amount reported and dividing this value by the standard deviation. The centered percentile score for each food parameter for each individual then multiplied by the respective food parameter effect score, which is derived from the literature review, in order to obtain a food parameter-specific DII score for an individual. All of the food parameter-specific DII scores then summed to create the overall DII score for every participant in the study. DII=b1*n1+b2*n2...........b31*n31, where b refers to the literature-derived inflammatory effects score for each of the evaluable food parameters and n refers to the food parameter-specific centered percentiles, which were derived from this case-controls dietary data. Of the theoretically possible list of 45 food parameters, a total of 31 were available from this FFQ and therefore could be used to calculate DII. We examined the ability of the dietary inflammatory index (DIITM) to predict the odds of glioma in a case-control study conducted from May 2011 to May 2012. This included 128 incident cases and 256 controls, frequency-matched to cases on age, who attended specialized centers in Iran. Logistic regression models were used to estimate multivariable odds ratios adjusted for variables like age, sex, body mass index, education, smoking, occupation, history of chemical exposure, history of cell phone use and energy intake. The mean DII value among cases was -0.57 (SD=0.68); among controls it was -0.84 (SD=0.65), indicating a more pro-inflammatory diet for cases (p-value=<0.01). Results obtained from modeling DII as a continuous variable in relation to odds of glioma showed a positive association after adjustment for age and sex (OR=1.90; 95% CI=1.36-2.67) and in the multivariate analysis (OR=2.12, 95% CI=1.44-3.13). When the analysis was carried out with DII expressed as a dichotomous variable, and adjusting for age and sex, subjects with DII score > -0.77 were had ≈90% higher odds of having glioma compared to subjects with DII ≤-0.77 (ORDII > -0.77/≤-0.77 =1.91; 95% CI=1.23-2.96). After multivariable adjustment, subjects with DII > -0.77 were over twice as likely to have glioma compared to subjects with DII ≤-0.77 (ORDII > -0.77/≤-0.77 =2.31; 95%CI=1.40, 3.84).Conclusion: In conclusion, subjects who consumed a more pro-inflammatory diet were at increased odds of glioma compared to those who consumed a more anti-inflammatory diet. Thus, encouraging intake of more anti-inflammatory dietary factors, such as omega-3 fatty acids, plant-based foods rich in fiber, beta-carotene and phytochemicals, and reducing intake of pro-inflammatory factors, such as fried foods or processed foods rich in saturated fat or trans fatty acids, may be a strategy for reducing risk of some cases of glioma.

کلیدواژه ها:

Glioma ، Inflammation ، Dietary Inflammatory Index (DII) ، Nutritional Assessment