Association between diet-related inflammation, all-cause, all-cancer, and cardiovascular disease mortality, with special focus on prediabetics: findings from NHANES III

Introduction Chronic inflammation is associated with increased risk of cancer, cardiovascular disease (CVD), and diabetes. The role of pro-inflammatory diet in the risk of cancer mortality and CVD mortality in prediabetics is unclear. We examined the relationship between diet-associated inflammation, as measured by dietary inflammatory index (DII) score, and mortality, with special focus on prediabetics. Methods This prospective cohort study used data from the Third National Health and Nutrition Examination Survey (NHANES III). We categorized 13,280 eligible participants, ages 20-90 years, according to glycosylated hemoglobin (HgbA1c) level and identified 2681 with prediabetes, defined as a glycosylated hemoglobin percentage of 5.7-6.4. Computation of DII scores and all statistical analyses were conducted in 2015. The DII was computed based on baseline dietary intake assessed using 24-h dietary recalls (1988-1994). Mortality was determined from the National Death Index records through 2006. Over follow-up ranging between 135 and 168 person-months, a total of 3016 deaths were identified, including 676 cancer, 192 lung cancer, 176 digestive-tract cancer, and 1328 CVD deaths. Cox proportional hazard regression was used to estimate hazard ratios. Results The prevalence of prediabetes was 20.19 %. After controlling for age, sex, race, HgbA1c, current smoking, physical activity, BMI, and systolic blood pressure, DII scores in tertile III (vs tertile I) was significantly associated with mortality from all causes (HR 1.39, 95 % CI 1.13, 1.72), CVD (HR 1.44, 95 % CI 1.02, 2.04), all cancers (HR 2.02, 95 % CI 1.27, 3.21), and digestive-tract cancer (HR 2.89, 95 % CI 1.08, 7.71). Findings for lung cancer (HR 2.01, 95 % CI 0.93, 4.34) suggested a likely effect. These results were moderately enhanced after additional adjustment for serum low-density lipoprotein and triglyceride and following eliminating deaths during the first year. Conclusions A pro-inflammatory diet, as indicated by higher DII scores, is associated with an increased risk of all-cause, CVD, all-cancer, and digestive-tract cancer mortality among prediabetic subjects.