Cooking methods are associated with inflammatory factors, renal function, and other hormones and nutritional biomarkers in older adults.

Evidence of the role of cooking methods on inflammation and metabolic health is scarce due to the paucity of large-size studies. Our aim was to evaluate the association of cooking methods with inflammatory markers, renal function, and other hormones and nutritional biomarkers in a general population of older adults. In a cross sectional analysis with 2467 individuals aged ≥ 65, dietary and cooking information was collected using a validated face-to-face dietary history. Eight cooking methods were considered: raw, boiling, roasting, pan-frying, frying, toasting, sautéing, and stewing. Biomarkers were analyzed in a central laboratory following standard procedures. Marginal effects from generalized linear models were calculated and percentage differences (PD) of the multivariable-adjusted means of biomarkers between extreme sex-specific quintiles (Q) of cooking methods consumption were computed ([Q5 - Q1/Q1] × 100). Participants' mean age was 71.6 years (53% women). Significant PD for the highest vs lowest quintile of raw food consumption was - 54.7% for high sensitivity-C reactive protein (hs-CRP), - 11.9% for neutrophils, - 11.9% for Growth Differentiation Factor-15, - 25.0% for Interleukin-6 (IL-6), - 12.3% for urinary albumin, and - 10.3% for uric acid. PD for boiling were - 17.8% for hs-CRP, - 12.4% for urinary albumin, and - 11.3% for thyroid-stimulating hormone. Concerning pan-frying, the PD was - 23.2% for hs-CRP, - 11.5% for IL-6, - 16.3% for urinary albumin and 10.9% for serum vitamin D. For frying, the PD was a 25.7% for hs-CRP, and - 12.6% for vitamin D. For toasting, corresponding figures were - 21.4% for hs-CRP, - 11.1% for IL-6 and 10.6% for vitamin D. For stewing, the PD was 13.3% for hs-CRP. Raw, boiling, pan-frying, and toasting were associated with healthy profiles as for inflammatory markers, renal function, thyroid hormones, and serum vitamin D. On the contrary, frying and, to a less extent, stewing showed unhealthier profiles. Cooking methods not including added fats where healthier than those with added fats heated at high temperatures or during longer periods of time.