Substituting whole grains for refined grains in a 6-wk randomized trial favorably affects energy-balance metrics in healthy men and postmenopausal women.
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/m2): <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 (ΔWG compared with ΔRG) 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. This trial was registered at clinicaltrials.gov as NCT01902394.
Jean Mayer USDA Human Nutrition Research Center on Aging and.
J Philip
0000-0002-5871-2241
JP
Karl
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Mohsen
M
Meydani
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Junaidah B
JB
Barnett
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Sally M
SM
Vanegas
School of Medicine, Tufts University, Boston, MA.
Barry
B
Goldin
School of Medicine, Tufts University, Boston, MA.
Anne
A
Kane
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Helen
H
Rasmussen
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Edward
E
Saltzman
Biomedical Informatics and Computational Biology and.
Pajau
P
Vangay
Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN; and.
Dan
D
Knights
Jean Mayer USDA Human Nutrition Research Center on Aging and.
C-Y Oliver
CO
Chen
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Sai Krupa
SK
Das
Bell Institute of Health and Nutrition, General Mills, Minneapolis, MN.
Satya S
SS
Jonnalagadda
Jean Mayer USDA Human Nutrition Research Center on Aging and.
Simin N
SN
Meydani
Jean Mayer USDA Human Nutrition Research Center on Aging and susan.roberts@tufts.edu.
Susan B
SB
Roberts
D050154:Adiposity; D001786:Blood Glucose / Q000378:metabolism; D004032:Diet; D004043:Dietary Fiber / Q000494:pharmacology* / Q000627:therapeutic use; D002149:Energy Intake; D004734:Energy Metabolism; D005243:Feces; D005247:Feeding Behavior; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy; D017698:Postmenopause; D012118:Resorcinols / Q000097:blood; D000067348:Whole Grains
D001786:Blood Glucose; D004043:Dietary Fiber; D012118:Resorcinols
body fat; body weight; continuous glucose monitoring; energy metabolism; fiber; glucose tolerance; glycemia; hunger; resting metabolic rate; thermogenesis