The association between dietary phytochemical index, metabolic health, and inflammation in older adults: a cross-sectional study

Abstract

Background The objective of this study was to evaluate the association between the Dietary Phytochemical Index (DPI) and inflammation in older adults. The research was structured as a population-based cross-sectional study carried out in health centers in Tehran, Iran.Methods We recruited 357 older male adults (60 + years of age). Dietary intake was assessed using a 147-item semi-quantitative food frequency questionnaire. DPI was estimated using the following formula: daily energy derived from phytochemical-rich foods (kcal)/total daily energy intake (kcal) & times; 100. Foods included in the phytochemical index consisted of fruits and vegetables, whole grains, nuts, olives and olive oil, seeds, legumes, and soy products. Tea, coffee, spices, and potatoes were excluded from the phytochemical index. Inflammation across tertiles of the DPI was evaluated using logistic regression analysis reported as odds ratio (OR) and 95 confidence intervals (CI) adjusted for energy intake, drug use, supplement use, socioeconomic status, BMI, physical activity, and age.Results DPI was not associated with hs-CRP (OR = 0.58; 95 CI 0.31-1.09; P = 0.09) or fibrinogen (OR = 0.79; 95 CI 0.44-1.43; P = 0.47) in the adjusted model. After adjusting for all confounders, participants in the third tertile of DPI compared with those in the first tertile had a higher HOMA-IR (Homeostasis model assessment-insulin resistance) (P = 0.002), insulin (P = 0.007), and marginally higher systolic blood pressure (P = 0.053) and lower LDL (P = 0.038) and total cholesterol (P = 0.032).Conclusions This cross-sectional study shows that a phytochemical-rich diet was not significantly associated with inflammatory markers. However, participants in the highest tertile showed higher HOMA-IR and insulin levels, a borderline increase in systolic blood pressure, and lower LDL and total cholesterol compared with those in the lowest tertile. Further research is recommended.