An Approach for Examining the Impact of Food Group‐Based Sources of Nutrients on Outcomes with Application to PUFAs and LDL
Authors: Tooze Janet A , Crandell Jamie L , The Natalie S , Couch Sarah C , Mayer‐Davis Elizabeth J , Koebnick Corinna , Liese Angela D 
Published: November 2023

The traditional approach used in nutritional epidemiology of describing the relationship between one nutrient and an outcome has identified specific mechanisms by which nutrients may affect health. For example, n‐3 and n‐6 polyunsaturated fatty acids (PUFA) have been associated with lower levels of LDL cholesterol. This approach, however, is a simplistic model of the impact of nutrition on health, as nutrients are consumed within foods within dietary patterns. Index‐based dietary patterns are generally comprised of components of nutrients or foods, but both are not considered simultaneously, and, therefore, provide little information in terms of potential mechanisms of action. We build on the concept of substitution effects, i.e., the change in the outcome when one dietary component is substituted for another, from a novel food‐group specific nutrients perspective. By fitting a series of nested regression models of the association between total PUFAs contained in foods and LDL cholesterol, we examined the effects of substituting a nutrient from one food group for another in the SEARCH Nutrition Ancillary Study, a study that investigates the relationship between dietary intake and complications of type 1 diabetes in youth. Total PUFAs were the sum of 18:3, 20:5, and 22:6 (n‐3) and 18:2 and 20:4 (n‐6) as derived from an FFQ, and were quantified by food group. Models were adjusted for other fat intake, carbohydrates, protein, alcohol intake, age, race, gender, and diabetes duration. The 1673 participants were on average 14 y old, 51% female, and had a diagnosis of type 1 diabetes for 3.6 years. The mean intake of PUFAs derived from an FFQ was 15.1 g/d, with the highest food group sources of PUFAs from fats and oils; meat, fish, and poultry; and legumes, nuts, and seeds. PUFAs from legumes, nuts, and seeds were inversely associated with LDL cholesterol (p<0.01) and PUFAs from poultry (and other non‐red meat animal proteins) were positively associated with LDL cholesterol (p<0.05); PUFAs from sweets, grains, red meat, fats and oils, snacks, dairy, and other sources were not significantly associated with LDL cholesterol. These results suggest that substituting PUFAs from legumes, nuts and seeds for PUFAs from poultry would be associated with a decrease in LDL cholesterol, possibly through differences in the specific PUFAs and the ratios of PUFAs contained within the food groups or of other constituents of these food groups. In conclusion, these findings illustrate the importance of considering both foods and nutrients when examining relationships between diet and health outcomes.

Support or Funding Information

The SEARCH Nutrition Ancillary Study is funded by 5R01DK077949 (Mayer‐Davis, PI). The SEARCH for Diabetes in Youth Cohort Study (1UC4DK108173‐01) is funded by the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases and supported by the Centers for Disease Control and Prevention. The Population Based Registry of Diabetes in Youth Study (RFP DP15‐002) is funded by the Centers for Disease Control and Prevention and supported by the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases.