The Resulting Variation in Nutrient Intake With the Inclusion of Walnuts in the Diets of Adults at Risk for Type 2 Diabetes: A Randomized, Controlled, Crossover Trial

Purpose: We previously demonstrated that including walnuts in the diets of adults at risk for type 2 diabetes mellitus (T2DM) led to improved overall diet quality. This report examines the specific changes in their nutrient intake. Design: This was a randomized, controlled, modified Latin square parallel design trial with 2 treatment arms. Participants were randomized to walnut intake with, or without, dietary advice to regulate caloric intake. Within each treatment arm, they were further randomized to one of 2 sequence permutations (walnut-included/walnut-excluded or walnut-excluded/walnut-included diet), with a 3-month washout between treatment phases. Setting: Community hospital in Lower Naugatuck Valley in Connecticut. Participants: Cohort of 112 participants (31 men and 81 women) at risk for T2DM. Intervention: Participants included 56 g (366 kcal) of walnuts in their daily diets for 6 months. Measures: Nutrient intake was assessed using web-based Automated Self-Administered 24-Hour Dietary Assessment. Analysis: Data were analyzed using generalized linear models. Results: Walnut inclusion led to increased intake of total fat, calcium, magnesium, thiamin, total saturated fatty acids, and monounsaturated and polyunsaturated fatty acids (379.0 +/- 90.3 g vs -136.5 +/- 92.7 g, P < .01; 230.7 +/- 114.2 mg vs -95.2 +/- 117.4 mg, P = .05; 111.0 +/- 33.9 mg vs -32.3 +/- 34.9 mg, P < .01; 0.28 +/- 0.2 mg vs -0.47 +/- 0.2 mg, P = .02; 8.6 +/- 3.4 g vs -1.1 +/- 3.5 g, P =.05; 6.3 +/- 3.9 g vs -6.3 +/- 4.0 g, P = .03; and 25.4 +/- 4.0 vs -6.6 +/- 4.2 g, P < .01, respectively). Vitamin C intake decreased (-65.3 +/- 55.3 mg vs 98.9 +/- 56.8 mg, P = .04). Protein intake increased from baseline with the inclusion of walnuts (20.0 +/- 8.8 g, P < .05). Walnut inclusion led to an increase in total calories consumed when caloric intake is not regulated. Conclusion: Including walnuts in the diets of these adults led to increased dietary intake of some nutrients associated with lower risk of developing T2DM and other cardiometabolic risk factors.