Inflammatory diets are associated with lower total iron binding capacity in sera of young adults

Chronic, systemic inflammation, which is associated with obesity and numerous other diseases, impairs iron status by increasing hepcidin concentration. Inflammation also decreases the concentration of transferrin, the main iron transport protein and a negative acute phase protein, which is indirectly assessed by measuring total iron binding capacity (TIBC). However, the contribution of diet-induced inflammation has not been studied. Data from two studies, namely Diet and Inflammation and Selenium and Inflammation Studies (total n=98) were used to assess the associations among Dietary Inflammatory Index (DII^®) scores derived from three-day dietary records, body mass index (BMI=weight[kg]/height[m]²), inflammatory and hematological markers among young adults with normal-weight, overweight or obesity. Subjects' diets were also categorized as less inflammatory diets (LID) and inflammatory diets (ID) using cluster analysis. Independent t-test and regression analyses were used to assess associations in the data. Intakes of iron, proteins, fat, fiber, and calories were higher in the LID group compared to the ID group (p<0.05). Demographic characteristics and concentrations of C-reactive protein (CRP) and iron status biomarkers did not differ significantly between the two groups (p>0.05). Higher DII score was associated with increasing CRP (β+SE=0.23+0.07, p=0.002) and lower TIBC (β+SE=-8.46+3.44, p=0.02), independent of BMI category. The LID diet was associated with higher TIBC (β+SE=29.87+10.75, p=0.007) compared to the ID diet. In conclusion, inflammatory diets may impair iron status by reducing the iron binding capacity of transferrin.