Question

John is a sedentary 60-year-old male who wants to lose 15 pounds. His usual diet is moderate in protein, some vegetables like potatoes and carrots, and whole grains and cereals. He’s decided that to lose weight, he’ll cut down on carbohydrates in his diet, and increase the protein content. However, John doesn’t want to give up his Starbuck’s caramel latte in the morning, so the coffee and two boiled eggs are his usual breakfast. His favorite lunch is a cheese burger, sans bun, with two slices of tomato and half of a small order of French fries. For dinner, he usually has a chicken breast with a small side salad. John is losing weight, but he’s now experiencing constipation and severe cramping. Question 1: Analyze John’s current diet and explain how it can affect his GI microbiome and overall GI tract health. Discuss in your answer some dietary components promote the growth of beneficial GI tract bacteria and the benefits these bacteria convey. Support your answer with data, facts, key terminology, specific examples and other information drawn from the textbook and at least one other supplemental sources.

Answer 1

John is currently following a keto diet plan which is rich in proteins and fats and low in carbohydrates. The keto diet is low in fibrous foods such as grains and legumes. The constipation experienced by John is due to the lack of adequate fibre in his diet.

High carbohydrate diets favor the Prevotella genus, whereas high protein and high fat diets play a major role in the development of Bacteroidetes species.

Gut microbiome plays a major role in digestive process and overall human health. Alterations of gut microbiome have evident consequences on intestinal homeostasis. Diet composition plays an important role in the control of gut microbiome and the gut microbiome can be modulated by diet components. The gut microbiome consists of bacteria, fungi, archaea and protozoa. The human microbiome consists of both anaerobic and aerobic microbial communities.

Protein, fat and carbohydrates are the major diet components of humans. The type and amount of carbohydrates, proteins and fats in the diet influence the gut microbiome in humans. This effect is related to the metabolites of the components present in the diet.

Dietary fiber is an important food component particularly derived from plants. Fiber concentration is lower in processed foods than in raw vegetables. Dietary fibres are partially metabolised by bacterial species and the remaining fibres are excreted.

In the GI tract, some carbohydrates such as starch and other non-starch polysaccharides cannot be directly metabolized by the host and these carbohydrates act as the important energy source for microbial growth. These carbohydrates are referred to as prebiotic. Prebiotics are the non-digestible component of food that benefits the host by stimulating the growth of the microbiome. Prebiotics are very important to induce changes in the composition of gut microbiome and confer benefits to the host health. Prebiotics stimulates the growth of bifidobacteria and lactobacilli.

Consumption of diets containing less fiber and vegetables result in the loss of important microbial communities. An individual whose diet is rich in fat and low in fibre tend to have more pathogenic bacteria than beneficial microbes. Balance of GI tract beneficial microbes could be achieved through symbiosis, which regulates the immune system and protects the host from various diseases. Symbiosis can be maintained through the consumption of balanced diets.