Dietary share of ultra-processed foods and metabolic syndrome in the US adult population.

This study sought to examine the relationship between dietary share of ultra-processed foods and metabolic syndrome among US adults. We studied 6, 385 participants from the cross-sectional National Health and Nutrition Examination Survey 2009-2014, aged 20+ years, with blood tests under fasting conditions and at least one 24-hour dietary recall. Food items were classified according to the extent and purpose of industrial food processing. Ultra-processed foods (UPF) are formulations of many ingredients, mostly of exclusive industrial use, that result from a sequence of industrial processes (hence ultra-processed). Metabolic Syndrome (MetS) was defined according to the 2009 Joint Scientific Statement as meeting three or more of the following criteria: (1) elevated waist circumference (2) elevated fasting plasma glucose (3) elevated blood pressure (4) elevated triglycerides (5) reduced high-density lipoprotein (HDL-C). Poisson regression models with robust variance adjusted for age, sex, race/ethnicity, family income, education, physical activity and smoking showed significant linear association between the dietary contribution of UPF and the prevalence of MetS (a 10% increase in contribution was associated with a 4% prevalence increase) (prevalence ratio -PR- = 1.04; 95% CI 1.02, 1.07). A dietary UPF contribution of >71% (5th population quintile) was associated with 28% higher prevalence of MetS compared to a contribution below 40% (1st population quintile) (PR = 1.28; 95% CI 1.09, 1.50). The association was stronger in young adults (PR between upper and lower quintiles = 1.94; 95% CI 1.39, 2.72) and decreased with age. These findings add to the growing evidence that UPF consumption is associated with diet-related non-communicable diseases.