Substituting whole grains for refined grains in a 6-wk randomized trial favorably affects energy-balance metrics in healthy men and postmenopausal women

卷:105

Karl, J. Philip ; Meydani, Mohsen ; Barnett, Junaidah B. ; Vanegas, Sally M. ; Goldin, Barry ; Kane, Anne ; Rasmussen, Helen ; Saltzman, Edward ; Vangay, Pajau ; Knights, Dan ; Chen, C-Y Oliver ; Das, Sai Krupa ; Jonnalagadda, Satya S. ; Meydani, Simin N. ; Roberts, Susan B.

Tufts Univ

关键词: body fat;    body weight;    continuous glucose monitoring;    energy metabolism;    fiber;    glucose tolerance;    glycemia;    hunger;    resting metabolic rate;    thermogenesis;   

DOI  :  10.3945/ajcn.116.139683

学科分类：食品科学和技术

【 摘 要 】

Background: The effect of whole grains on the regulation of energy balance remains controversial. Objective: We aimed to determine the effects of substituting whole grains for refined grains, independent of body weight changes, on energy-metabolism metrics and glycemic control. Design: The study was a randomized, controlled, parallel-arm controlled-feeding trial that was conducted in 81 men and postmenopausal women [49 men and 32 women; age range: 40-65 y; body mass index (in kg/m(2)): < 35.0]. After a 2-wk run-in period, participants were randomly assigned to consume 1 of 2 weight-maintenance diets for 6 wk. Diets differed in whole-grain and fiber contents [mean +/- SDs: whole grain-rich diet: 207 +/- 39 g whole grains plus 40 +/- 5 g dietary fiber/d; refined grain-based diet: 0 g whole grains plus 21 +/- 3 g dietary fiber/d] but were otherwise similar. Energy metabolism and body-composition metrics, appetite, markers of glycemic control, and gut microbiota were measured at 2 and 8 wk. Results: By design, body weight was maintained in both groups. Plasma alkylresorcinols, which are biomarkers of whole-grain intake, increased in the whole grain-rich diet group (WG) but not in the refined grain-based diet group (RG) (P-diet-by-time interaction, 0.0001). Beta +/- SE changes (Delta WG compared with Delta RG) in the resting metabolic rate (RMR) (43 +/- 25 kcal/d; P = 0.04), stool weight (76 +/- 12 g/d; P, 0.0001), and stool energy content (57 +/- 17 kcal/d; P = 0.003), but not in stool energy density, were higher in the WG. When combined, the favorable energetic effects in the WG translated into a 92-kcal/d (95% CI: 28, 156-kcal/d) higher net daily energy loss compared with that of the RG (P = 0.005). Prospective consumption (P = 0.07) and glycemia after an oral-glucose-tolerance test (P = 0.10) trended toward being lower in the WG than in the RG. When nonadherent participants were excluded, between-group differences in stool energy content and glucose tolerance increased, and between-group differences in the RMR and prospective consumption were not statistically significant. Conclusion: These findings suggest positive effects of whole grains on the RMR and stool energy excretion that favorably influence energy balance and may help explain epidemiologic associations between whole-grain consumption and reduced body weight and adiposity.