Adherence to low carbohydrate diet in relation to glioma: A case-control study.

Background: Observational studies that investigated the association between adherence to low carbohydrate diet and odds of glioma are sparse. This is particularly relevant in developing countries where dietary carbohydrate intake is very high.

Objective: This study was, therefore, conducted to investigate the association between adherence to low carbohydrate dietary pattern and odds of glioma among Iranian adults.

Methods: In this hospital-based case-control study, 128 newly diagnosed glioma cases were recruited and 256 age- and sex-matched subjects were enrolled as controls. Dietary intakes were examined by the use of a 126-item validated FFQ. Low carbohydrate diet (LCD) score was computed for each participant based on deciles of percentages of energy from carbohydrates, proteins, and fats. Individuals in the lowest decile of carbohydrate consumption received 10 points. Participants in second decile received 9 points and so on down to participants in the highest decile received 1 points. For fat and protein intakes, the points assigned to deciles were reversed; such that those in the highest decile received 10 points and those in the lowest decile received 1 point. We then summed all points of the three macronutrients to achieve the overall diet score, which ranged from 3 (highest carbohydrate intake and lowest fat and protein intakes) to 30 (lowest carbohydrate intake and highest fat and protein intakes). The higher the score, the greater adherence to the LCD dietary pattern.

Results: After adjustment for age and sex, we found that individuals in top tertile of LCD score were 60% less likely to have glioma compared with those in the bottom tertile (OR: 0.40; 95% CI: 0.23, 0.67). Additional controlling for other potential confounders made the association slightly attenuated (OR: 0.49; 95%CI: 0.26, 0.93). Further adjustment for dietary nutrient intakes strengthened the association (OR: 0.32; 95%CI: 0.12, 0.81). After additional controlling for BMI, we found that adherence to LCD was protectively associated with reduced odds of glioma (OR: 0.32; 95%CI: 0.12, 0.81).

Discussion: We found an inverse association between adherence to LCD and odds of glioma among Iranian population. Prospective cohort studies are needed to confirm these findings.