Associations between healthy eating patterns and immune function or inflammation in overweight or obese postmenopausal women

Background: The link between poor nutritional status and impaired immune function is well established; however, most studies have focused on individual nutrients instead of overall dietary patterns. Objective: Our objective was to investigate associations between 3 indexes of overall diet quality [the Diet Quality Index (DQI), the DQI including supplementary calcium (DQI-Ca), and the Healthy Eating Index (HEI)] and biomarkers of inflammation and immunity. Design: This cross-sectional study included 110 overweight or obese postmenopausal women. Dietary intake measured by food-frequency questionnaire was used to calculate diet quality scores. C-reactive protein (CRP) and serum amyloid A (SAA) were measured by latex-enhanced nephelometry. Flow cytometry was used to measure natural killer (NK) cell cytotoxicity and to enumerate and phenotype lymphocyte subsets. T lymphocyte proliferation was assessed by 3H-thymidine incorporation as well as by the carboxyfluorescein- succinimidyl ester method of cell division tracking. Multivariable-adjusted linear regression analysis was used to investigate associations between diet quality scores and markers of inflammation and immune function. Results: Higher diet quality was associated with increased proportions of cytotoxic and decreased proportions of helper T lymphocytes. CRP and SAA concentrations were higher among women with a lower-quality diet; these associations became nonsignificant after adjustment for body mass index or percentage body fat. We observed limited evidence for an association between healthy eating patterns and greater lymphocyte proliferation and no evidence for an association with NK cell cytotoxicity. Conclusion: Our results provide limited evidence that healthy eating patterns contribute to enhanced immune function and reduced inflammation in overweight and obese postmenopausal women. © 2007 American Society for Nutrition.