title: Fecal lactic acid bacteria increased in adolescents randomized to whole-grain but not refined-grain foods, whereas inflammatory cytokine production decreased equally with both interventions.
abstract: The intake of whole-grain (WG) foods by adolescents is reported to be approximately one-third the recommended intake of 48 g/d. This 6-wk randomized interventional study determined the effect of replacing grains within the diet with refined-grain (RG; n = 42) or WG (n = 41) foods/d on gastrointestinal and immune health in adolescents (aged 12.7 ± 0.1 y). A variety of grain-based foods were delivered weekly to participants and their families. Participants were encouraged to eat 3 different kinds of study foods (e.g., bread, cereals, snacks)/d with goals of 0 g/d (RG) and 80 g/d (WG). Stool samples were obtained during the prebaseline and final weeks to measure bifidobacteria and lactic acid bacteria (LAB) using qPCR. Stool frequency was recorded daily. Blood was drawn at baseline and at final visits for immune markers. Across groups, total-grain intake increased by one serving. The intake of WG was similar at baseline (18 ± 3 g) between groups but increased to 60 ± 5 g in the WG group and decreased to 4 ± 1 g in the RG group. Fecal bifidobacteria increased from baseline with both interventions, but LAB increased (P < 0.05) from baseline [2.4 ± 0.2 log(10) genome equivalents (eq)] to wk 6 (3.0 ± 0.2 log(10) genome eq) in the WG group but not in the RG group (baseline: 2.9 ± 0.2 log(10) genome eq; wk 6: 3.0 ± 0.1 log(10) genome eq). There was no difference in stool frequency, serum antioxidant potential, or in vitro LPS-stimulated mononuclear cell production of inflammatory cytokines between groups. However, across both groups the number of daily stools tended to increase (P = 0.08) by 0.0034 stools/g WG or by 0.2 stools with 60 g WG, mean antioxidant potential increased by 58%, and mean production of TNF-α, IL-1β, and IL-6 decreased by 24, 22, and 42%, respectively, between baseline and wk 6. Overall, incorporating either WG or RG foods increased serum antioxidant concentrations and decreased inflammatory cytokine production; however, WG study foods had more of an effect on aspects of gastrointestinal health.
authors.affiliation: Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL, USA. henken@ufl.edu
authors.forename: Bobbi
authors.initials: B
authors.lastname: Langkamp-Henken
authors.forename: Carmelo
authors.initials: C
authors.lastname: Nieves
authors.forename: Tyler
authors.initials: T
authors.lastname: Culpepper
authors.forename: Allyson
authors.initials: A
authors.lastname: Radford
authors.forename: Stephanie-Anne
authors.initials: SA
authors.lastname: Girard
authors.forename: Christine
authors.initials: C
authors.lastname: Hughes
authors.forename: Mary C
authors.initials: MC
authors.lastname: Christman
authors.forename: Volker
authors.initials: V
authors.lastname: Mai
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Dahl
authors.forename: Thomas
authors.initials: T
authors.lastname: Boileau
authors.forename: Satya S
authors.initials: SS
authors.lastname: Jonnalagadda
authors.forename: Frank
authors.initials: F
authors.lastname: Thielecke
mesh_terms: D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004032:Diet; D002523:Edible Grain; D007887:Fabaceae; D005243:Feces / Q000382:microbiology*; D005260:Female; D005504:Food Analysis; D005511:Food Handling; D005638:Fruit; D006801:Humans; D007778:Lactobacillus / Q000302:isolation & purification*; D008297:Male; D014675:Vegetables
chemical_list: D016207:Cytokines