Reduces metabolizable, available energy to the host, as more energy is instead channelled to to the gut microbiome. Evidenced by:

• Increased microbial fermentation

• Increased fecal and serum SCFA levels

• Increased fecal energy loss

Change in species abundance

• Particularly more fibre degraders + SCFA producers

Supports weight loss by maintaining a calorie/energy deficit.

• 116 kcal/day deficit

Corbin, D.E., et al. 2023. Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial. Nature Communications. 14(1): 3161. doi: 10.1038/s41467-023-38778-x

Hill O.J., et al. 2013. The Importance of Energy Balance. Endocrinology. 9(2): 111-115. Doi: 10.17925/EE.2013.09.02.111

Roberts S.B., 2022. Dietary Energy. Advances in Nutrition. 13(6): 2681-2685. doi:10.1093/advances/nmac092

Blundell J.E., 2015. Appetite control and energy balance: impact of exercise. Obesity Reviews. 1: 67-76. Doi: 10.1111/obr.12257

Brown H.E., 2016. Family-based interventions to increase physical activity in children: a systematic review, meta-analysis and realist synthesis. Obesity Reviews. 17(4): 345-360. doi:10.1111/obr.12362

Ryan. D. 2020. Energy Balance and Weight Loss for Diabetes Remission. Diabetes Spectrum. 33(2):117-124. Doi: 10.2337/ds20-0005

Montenegro. J., et al. 2023. Exploring the Influence of Gut Microbiome on Energy Metabolism in Humans. Advances in Nutrition. 14(4): 840-857. Doi: 10.1016/j.advnut.2023.03.015

Wang. Y., et al. 2020. Nuciferine modulates the gut microbiota and prevents obesity in high-fat diet-fed rats. Experimental Molecular Medicine. 13(1): 1-24. Doi: 10.1038/s12276-020-00534-2

Zhang. X., et al. 2020. Dietary cholesterol drives fatty liver-associated liver cancer by modulating gut microbiota and metabolites. Gut. 70(4): 761-774. Doi: 10.1136/gutjnl-2019-319664

Maximized availability of dietary substrates to the gut microbiome

Four components:

• Dietary fibre

• Resistant startch

• Large food particle size

• Limited processed food

Ex. whole grains, lentils, fruits, vegetables

Served as a negative control

Formulated to be representative of typical diet based on a person living in the United States

Opposite of the four components in MBD, but still in easily digestible form

Ex. Processed & cured meats, butter, cheese

Metabolic ward provides a controlled environment

• Allows for causative results to be determined

• Ensures that the sole difference between the groups is due to the assigned diet

  
  

Randomized crossover design

• All participants are put in both conditions

• Each person acts as their own control, eliminating inter-subject variability. This is very important as the gut microbiome varies a lot from person to person.

Alpha diversity was shown to be statistically insignificant between the microbiomes on WD and MBD

Not much specifics on pathways of the human host-diet-gut microbiome interactions

• Cannot confidently establish if individual effects are due to diet, microbiome, or both

Repeating the study

• Incorporating diets from other cultures to have a more comprehensive comparison

• Finding more participants for a larger sample size to confirm and expand findings

• Perform subgroup analysis, to see if effects vary by biological sex, weight group, or any other metrics

Researching Microbiome Enhancer Diet as a framework for developing a diet for weight management strategies

• Could help to inform methods by which to approach reducing global obesity

Elucidating how the gut microbiome and Microbiome Enhancer Diet affect each other

• Determining specific mechanisms underlying delivery of dietary substrates to the gut microbiome

• Targeting these mechanisms with personalised nutrition approaches

• Optimizing energy balance + SCFA production through personalised diets

Balance between the energy a host intakes and the energy expended

+ energy balance = energy intake > energy expended

- energy balance = energy intake < energy expended

We intake energy through consuming food and expend energy through metabolism

Disruption of energy balance leads to cardiovascular and metabolic disorders(Blundell et al., 2015)

+ energy balance leads to detrimental effects

• Obesity(our body stores the excess energy that we intake as fat)(Brown et al., 2016)

• Insulin resistance leads to high blood sugar(Type II diabetes)(Ryan. D., 2020)

Energy that is taken up by the host through the intake of food

Diet that is high in fiber leads to more nutrients for bacteria

High-fiber diet is associated growth of beneficial bacteria like bacteriodetes and bifidobacteria

• These bacteria allows for the fermentation of SCFAs(butyrate, propionate)

• SCFAs that are produced influences the hosts ability to extract energy from food

Most of the previous studies done were pre-clinical trials therefore, there was a lack of human data

Could not conclude if a certain diet promoted growth of beneficial bacteria or if the certain bacteria was already present(lack of data on the composition of gut microbiome)

Studies Lack data on how the diet-gut interaction affects host metabolizable energy

Researchers in this study used Nuciferine(organic compound) which altered gut microbiota composition in mice

• Nuciferine increased Bacteriodetes(SCFA producing bacteria) and decreased firmicutes

• Nuciferine increased the composition of SCFAs producing bacteria, promoting SCFA production

• This change prevented weight gain and fat accumulation in high fat diet mice

Limitation: Murine Study which is a clinical study

Researchers in this study fed mice with a high fat & high cholesterol diet(HFHC) and a Mediterranean diet(MD)

• Found that HFHC diet decreases the composition of bifidobacterium and bacteriodetes as opposed to the MD

• Decrease in these beneficial bacteria lead to increase in detrimental conjugated bile acids which potentially leads to Nonalcoholic fatty liver diesase(Metabolic Syndrome)

Aimed to address the gaps in literature in other papers

To identify the changes in host metabolizable energy in response to different diets

To investigate the changes in microbiome composition due to different diets

Most previous studies were based on preclinical models, but this study provided strong evidence based on a highly controlled clinical trial.

• Results from preclinical models suggested that more energy channelled to microbes would lead to more energy available to host

• This study disproved that and demonstrated the opposite in clinical trials; that is, more energy channelled to microbes results in less energy was available to the host

Incorporated precise methodology and rigorous controls, especially with regard to the metabolic ward, that helped to determine causative results

• This was lacking in many prior human clinical trials that aimed to study relationship between gut microbiome and energy loss

Relationship between gut microbiome and diet presents another angle to understand energy balance and weight management, which is important in finding solutions for obesity

• Obesity is a very current and growing interest in health research as it is a significant risk factor for many chronic diseases that are leading causes of death, such as cardiovascular disease or atherosclerosis.