Role of whole grains versus fruits and vegetables in reducing subclinical inflammation and promoting gastrointestinal health in individuals affected by overweight and obesity: a randomized controlled trial.

Julianne C Kopf, Mallory J Suhr, Jennifer Clarke, Seong-Il Eyun, Jean-Jack M Riethoven, Amanda E Ramer-Tait, Devin J Rose

Journal: Nutrition journal 2019;17(1):72

PMID: 30060746

Free Full Text on BioMed Central View on PubMed

Plain Language Summary

Poor diet is the leading risk factor for premature death and disability in the United States. Poor diets lead to metabolic syndrome and its associated diseases such as heart disease and diabetes. The purpose of this study was to determine the impact of increasing intake of wholegrains or fruit and vegetables against a typical Western diet on inflammatory makers and gut microbiota composition. The study was a randomized, parallel arm feeding trial which enrolled fifty-two participants. The subjects were randomized into three groups (control, wholegrains, and fruit and vegetables). Results indicate that the wholegrain and fruit and vegetable diets had significant positive impacts on inflammatory markers. Interestingly, while both treatment groups decreased inflammatory markers, each decreased a different biomarker. The treatments induced individualised changes in microbiota composition such that treatment group differences were not identified. Authors conclude that wholegrain and fruit and vegetable diets have a positive impact on metabolic health in individuals affected by overweight or obesity.

Abstract

BACKGROUND

Whole grains (WG) and fruits and vegetables (FV) have been shown to reduce the risk of metabolic disease, possibly via modulation of the gut microbiota. The purpose of this study was to determine the impact of increasing intake of either WG or FV on inflammatory markers and gut microbiota composition.

METHODS

A randomized parallel arm feeding trial was completed on forty-nine subjects with overweight or obesity and low intakes of FV and WG. Individuals were randomized into three groups (3 servings/d provided): WG, FV, and a control (refined grains). Stool and blood samples were collected at the beginning of the study and after 6 weeks. Inflammatory markers [tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), lipopolysaccharide binding protein (LBP), and high sensitivity C-reactive protein (hs-CRP)] were measured. Stool sample analysis included short/branched chain fatty acids (S/BCFA) and microbiota composition.

RESULTS

There was a significant decrease in LBP for participants on the WG (- 0.2 μg/mL, p = 0.02) and FV (- 0.2 μg/mL, p = 0.005) diets, with no change in those on the control diet (0.1 μg/mL, p = 0.08). The FV diet induced a significant change in IL-6 (- 1.5 pg/mL, p = 0.006), but no significant change was observed for the other treatments (control, - 0.009 pg/mL, p = 0.99; WG, - 0.29, p = 0.68). The WG diet resulted in a significant decrease in TNF-α (- 3.7 pg/mL; p < 0.001), whereas no significant effects were found for those on the other diets (control, - 0.6 pg/mL, p = 0.6; FV, - 1.4 pg/mL, p = 0.2). The treatments induced individualized changes in microbiota composition such that treatment group differences were not identified, except for a significant increase in α-diversity in the FV group. The proportions of Clostridiales (Firmicutes phylum) at baseline were correlated with the magnitude of change in LBP during the study.

CONCLUSIONS

These data demonstrate that WG and FV intake can have positive effects on metabolic health; however, different markers of inflammation were reduced on each diet suggesting that the anti-inflammatory effects were facilitated via different mechanisms. The anti-inflammatory effects were not related to changes in gut microbiota composition during the intervention, but were correlated with microbiota composition at baseline.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT02602496 , Nov 4, 2017.

Address: Department of Food Science and Technology, University of Nebraska-Lincoln, 1901 North 21st Street, Lincoln, NE, 68588-6205, USA.; Department of Statistics, University of Nebraska-Lincoln, Lincoln, NE, USA.; Nebraska Food for Health Center, University of Nebraska-Lincoln, 1901 North 21st Street, Lincoln, NE, 68588-6205, USA.; Department of Life Science, Chung-Ang University, Seoul, South Korea.; Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, USA.; Department of Food Science and Technology, University of Nebraska-Lincoln, 1901 North 21st Street, Lincoln, NE, 68588-6205, USA. [email protected].; Nebraska Food for Health Center, University of Nebraska-Lincoln, 1901 North 21st Street, Lincoln, NE, 68588-6205, USA. [email protected].; Department of Agronomy & Horticulture, University of Nebraska-Lincoln, 1901 North 21st Street, Lincoln, NE, 68588-6205, USA. [email protected].

DOI: 10.1186/s12937-018-0381-7

Patient Centred Factor

Triggers: Whole-grain diet

Clinical Imbalances

Immune and inflammation Gastro-intestinal

Laboratory Testing

Blood Stool

Modifiable Lifestyle Factors

Diet

Jadad Score

Allocation Concealment

Yes

Nutrition Evidence Keywords

Diabetes BMI Obesity Overweight Body mass index Metabolic syndrome Short-chain fatty acids Heart disease Gut-microbiota Gastrointestinal diseases

Link outs

Free resources

Full Text Sources:

Medical:

https://clinicaltrials.gov/search?term=AREA%5BRefe...

Other Literature Sources:

Miscellaneous:

https://assays.cancer.gov/non-CPTAC-1140

Research Materials:

https://antibodies.cancer.gov/detail/CPTC-CRP-1

MeSH Terms: Acute-Phase Proteins, Adult, Aged, Carrier Proteins, Diet, Feces, Female, Fruit, Gastrointestinal Microbiome, Humans, Inflammation, Interleukin-6, Male, Membrane Glycoproteins, Middle Aged, Obesity, Overweight, Tumor Necrosis Factor-alpha, Vegetables, Whole Grains