A randomized controlled-feeding trial based on the Dietary Guidelines for Americans on cardiometabolic health indexes

Authors: KRISHNAN, SRIDEVI - University Of California, Davis; ADAMS, SEAN - University Arkansas For Medical Sciences (UAMS); Allen, Lindsay - A; Laugero, Kevin; Newman, John; Stephensen, Charles; BURNETT, DUSTIN - University Of California, Davis; WITBRACHT, MEGAN - University Of California, Davis; WELCH, LUCAS - University Of California, Davis; Que, Excel; Keim, Nancy

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2018
Publication Date: 8/7/2018
Citation: Krishnan, S., Adams, S.H., Allen, L.H., Laugero, K.D., Newman, J.W., Stephensen, C.B., Burnett, D.J., Witbracht, M., Welch, L.C., Que, E.S., Keim, N.L. 2018. A randomized controlled-feeding trial based on the Dietary Guidelines for Americans on cardiometabolic health indexes. American Journal of Clinical Nutrition. 108(2):266-278. https://doi.org/10.1093/ajcn/nqy113.
DOI: https://doi.org/10.1093/ajcn/nqy113

Interpretive Summary: Cognitive decline has been associated with metabolic diseases, such as type 2 diabetes and cardiovascular disease. Dietary habits and the foods one eats can also positively and negatively influence cognitive function, but studies testing how whole food diets alter cognitive function over time are scarce. In fact, until now, studies testing whether a diet based on the Dietary Guidelines for Americans (DGA) affects cognitive function have not been conducted. In a study comparing the effects of whole food diets based on the DGA and on a typical American diet (TAD) higher in saturated fat and added sugar, and lower in fiber, we found in women at risk for cardiovascular and metabolic disease the DGA diet to be associated with improvements in the ability to more quickly respond (psychomotor speed) to cognitive tasks and in decision making. In both the DGA and TAD groups, we also found that decision making was associated with better longer term control of blood glucose. Surprisingly, unlike in the DGA group, we observed improvements in working memory in the TAD group. Together, our results are the first to report significant changes in cognitive function between whole food diets based on the DGA and TAD in women at risk for cardiovascular or metabolic disease. Our work supports a growing awareness of the clinically important links between diet and cognitive function, which is important given the growing incidence of cognitive decline and associated cognitive diseases like Alzheimer's and age related dementia.

Technical Abstract: Background: Metabolic syndrome increases risk for developing type 2 diabetes, cardiovascular disease, and cognitive impairment. Evidence suggests that healthy eating patterns, such as the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) diet, are beneficial for cognitive function. However, the effects of the Dietary Guidelines for Americans (DGA) on cognitive performance have yet to be tested in a randomized controlled trial. Objective: We compared the effects of a 2010 DGA-diet with a typical American diet (TAD) on cognitive performance in women with increased risk for cardiometabolic disease. Design: Fifty-two overweight or obese women with evidence of insulin resistance or dyslipidemia participated in the randomized, double-blind, controlled feeding study. During the 8-week intervention, subjects were fed a eucaloric diet based on the DGA (n = 28) or a TAD (n = 24), which was designed using the dietary component of the 2009-2010 National Health and Nutrition Examination Survey. Cognitive function was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the Iowa Gambling Task (IGT). Psychomotor function and subdomains of executive function, including spatial planning, spatial working memory, response inhibition and decision making, were evaluated. Results: Psychomotor speed was significantly improved by the DGA diet compared to the TAD. Modest improvements in decision making were observed in the DGA group, but these improvements became significant when adjusting for changes in HbA1c. Spatial working memory was significantly improved in the TAD, but not the DGA group. Conclusions: The DGA was beneficial for psychomotor speed, but a nutrient-adequate TAD improved spatial working memory in women with elevated cardiometabolic risk. Furthermore, there may be a link between the beneficial effects of a healthy diet on decision making and improvements in glucose control.