Greater frequency of cooking dinner at home and more time spent cooking are inversely associated with ultra-processed food consumption among US adults

Background Cooking at home has been promoted as a strategy to improve diet quality, however, the association between cooking behavior and ultra-processed food intake is unknown. Objective The objective of this study was to examine associations between frequency of cooking dinner at home and time spent cooking dinner with ultra-processed food intake. Design Cross sectional, nationally representative data from the 2007-2010 National Health and Nutrition Examination Survey were analyzed. Participants /setting: Participants were 9,491 adults (aged ≥20 years) in the United States. Main outcome measures The main outcome measure was the proportion of energy intake (averaged from two 24-hour dietary recalls) from the four Nova food processing groups: 1) unprocessed or minimally processed foods; 2) processed culinary ingredients; 3) processed foods, and 4) ultra-processed foods. Statistical analyses performed Separate linear regression models examined associations between cooking frequency and time spent cooking dinner and proportion of energy intake from the four Nova food processing groups, adjusting for socio-demographic characteristics and total energy intake. Results Ultra-processed foods comprised >50% of energy consumed independent of cooking frequency or time spent cooking. Higher household frequency of cooking dinner and greater time spent cooking dinner were both associated with lower intake of ultra-processed foods (p-trends<0.001) and higher intake of unprocessed or minimally processed foods (p-trends<0.001) in a dose response manner. Compared to cooking 0-2 times/week, adults who cooked dinner 7 times/week consumed on average 6.30% (95% CI: -7.96%, -4.64%, p<0.001) less energy from ultra-processed foods. Adults who spent >90 minutes cooking dinner consumed 4.28% less energy from ultra-processed foods (95% CI: -6.08%, -2.49%, p<0.001) compared to those who spent 0-45 minutes cooking dinner. Conclusions Cooking at home is associated with lower consumption of ultra-processed foods and higher consumption of unprocessed or minimally processed foods. However, ultra-processed food intake is high among US adults regardless of cooking frequency.