Paleolithic Diet Fraction: A Measure of Adherence to the Paleolithic diet

Abstract: Background: A measure of adherence to the Paleolithic diet not based on population-relative food group intakes was lacking. The aim of this thesis was to evaluate the usefulness of the Paleolithic Diet Fraction (PDF), a novel measure of adherence to the Paleolithic diet, calculated as the fraction of total food group intake derived from Paleolithic food groups. Methods: PDF was calculated from four-day weighed food records in Papers I, II, and IV, and from a modified diet history method including seven-day food records in Paper III. Papers I and II examined associations between PDF and cardiometabolic outcomes in post hoc analyses of randomized controlled trials (RCTs) comparing the Paleolithic diet with a Mediterranean-like diet and a diabetes diet, respectively. Paper III examined associations between PDF and mortality, and cardiovascular disease incidence in 24,104 participants of the Malmö Diet and Cancer cohort study. Paper IV examined associations between PDF and cardiometabolic outcomes, and correlations between PDF and the population-relative, food group intake–based Paleolithic Diet Score (PDS), in a post hoc analysis of an RCT without significant findings when comparing healthy diets with and without cereal grains. Results: PDF was around 80% for the Paleolithic diet in Papers I and II, and between 30–50% for other diets in Papers I–IV. In Papers I and II, higher PDF was associated with healthier levels of cardiometabolic outcomes such as glycemic control, waist circumference, body weight, and blood lipids. In Paper III, PDF was inversely associated with mortality and cardiovascular disease incidence. In Paper IV, there were moderate to strong correlations between PDF and PDS, and neither was associated with cardiometabolic outcomes. Conclusion: The PDF was demonstrated to be a feasible, reliable, and valid measure of adherence to the Paleolithic diet across diverse populations and study designs.