The gut plays an important role in health. It contains trillions of microorganisms. These microorganisms help break down food, synthesise essential nutrients and regulate the immune system. It is connected with all the vital organs and communicates with these organs. A balanced gut microbiome is essential for maintaining digestive health, supporting immunity and preventing various chronic diseases. 

Gut health is affected by various reasons like 

• Stress
• Poor diet
• Lack of exercise
• Overuse of antibiotics
  
  

This can disrupt the balance of the gut microbiota, leading to digestive issues and even more serious conditions. 

Maintaining gut health is not only about treating these issues but also about providing an environment where the beneficial bacteria can grow. 

Recently everyone has been talking about gut health and how gut health is important. This blog dives deep and explains gut health, its importance, function, impact on health and the right food that you should be eating. 

Gut microbiota and gut microbiome 

Microbiota and microbiome are interchangeable terms. 

A unique ecosystem that has the entire habitat of the body which includes microorganisms, genomes, and surrounding environmental conditions is called the gut microbiome. 

Trillions of microscopic organisms inhabit the biome which is your gut, located inside your intestines. These microorganisms include fungus, viruses, and parasites and thousand kinds of bacteria are referred to as gut microbiota. 

The first gut microbes are encountered as infants at the time of birth or through breastfeeding. As you grow, exposure to the environment and various foods and diets have an impact on your gut microbes. 

For a gut microbiota to fully develop, it takes 3-5 years from the first microbial exposure. Any disturbance occurring in the early stages can inhibit the development of the microbiota. 

Is the gut microbiome important?

The gut microorganisms and the host (that is the human body) have a mutual relationship. The relationship goes both ways, the microbes use the food we eat and also protect our body from potentially harmful substances. 

The gut microbiome is important because it keeps an equilibrium in the gut and protects the immune system from foreign substances. If the equilibrium breaks then the immune system gets suppressed and the whole ecosystem collapses. 

These microorganisms have vital functions in humans. Studies have shown that gut microorganisms have a beneficial role in conditions that disturb the ecosystem like asthma, autistic spectrum disorder, cancer, coeliac disease, eczema, diabetes, malnutrition, obesity, heart disease and multiple sclerosis.

Functions of gut microbiota  

• Obtaining energy from the digested food.
  
  
• Protect the body against harmful pathogens.
  
  
• Immune function regulation.
  
  
• Strengthening the gut and intestine biochemical barriers.
  
  

Impact of gut microbiota on health

Immunity 

As infants are exposed to microbes even before birth according to some studies the immune system of the body learns how to react to microbes after encountering them. This is because of adaptive immunity. As the body reacts immediately and more effectively, any disease-causing organisms are stopped. 

Disease 

The human gut has connections to all the organs through the gut-organ connection. A dysbiosis of the gut can lead to many health risks varying from skin disorder to the development of type 2 diabetes. 

Low microbial diversity in the gut has a link to an increase in body weight. The gut flora and metabolic syndrome are connected. 

Additionally, the microbiota is crucial in preventing the expansion of foreign populations in the gut that might otherwise lead to illness since the “good” bacteria surpass the “bad,” and some of them even release substances that reduce inflammation. 

Antibiotic-induced disruption of the microbiota can also result in disease, including antibiotic-resistant diseases.

Endocrine system 

The gut has an impact on the largest endocrine system. This endocrine system produces many hormones which are responsible for regulating metabolism, altering blood sugar levels, hunger and satiety. It helps regulate the metabolism of the human body, and the production of endocannabinoids and neurotransmitters.     

Gut health 

Even gut health can be affected by microbiomes and cause intestinal diseases like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). People with IBS may experience bloating, abdominal pain and cramps can be due to dysbiosis of the gut. These symptoms are experienced due to the production of excess gas and other chemicals. 

Leaky gut syndrome and IBS symptoms can be prevented and reduced by beneficial bacteria like Bifidobacteria and Lactobacilli which are found in probiotics. 

Heart health 

A participation study found that gut microbiomes play a vital role in promoting HDL cholesterol (otherwise known as good cholesterol) and triglycerides. 

Gut-brain axis

The gut has connections with many organs in the body; one such connection is the gut-brain connection. Effects of the stomach and intestines have a direct connection with the brain. So the connection can go like this, the troubled intestine sends a signal to the brain and the brain sends a signal to the gut, this distress in the intestine can be the cause of anxiety or stress. 

We may have heard people say they have a stomach upset because they are stressed, this is due to the gut-brain connection. 

Is this connection needed? – yes! As the brain and digestive system develop together and help in survival. Both of them need to be in close connection to make sure that the body gets all the required nutrients. 

gut-brain axis influences on:

• Hunger and feeling satiated
• Food cravings and food preference 
• Food intolerance and sensitivities
• Motility of gut
• Digestion of the food 
• Overall metabolism and immunity
• Mood and behaviour
• Stress
• Sensitivity to pain
• Cognitive function
  
  

Diet and gut

Before knowing what food is best for gut health, let us understand what are prebiotics, and probiotics and why it is important for gut health. 

Probiotics 

Probiotics are defined as live microorganisms that provide a health benefit to the host (human body) when administered in adequate amounts.

Food sources include:

• Kimchi, sauerkraut, and pickled vegetables.
• Yoghurt, kefir, and cottage cheese
• Miso and tempeh.
  
  

Pre-biotics 

Fermentable dietary fibre known as pre-biotics is described as a substrate that is selectively utilised by host (human) microorganisms and has health benefits among the various forms of fermentable dietary fibre. Some undigested pre-biotics are digested in the upper gastrointestinal tract by certain bacteria. 

Food sources include:

• Legumes and pulses 
• Chia seeds, pumpkin seeds, flaxseeds, and sunflower seeds 
• Brown rice, barley, quinoa, and oats
• Walnuts, pistachios, almonds, and pecans
• Brussels sprouts, artichokes, carrots, broccoli, and sweet potatoes
• Pears, berries, banana, and apple.
  
  

There is a third supplement called postbiotics. 

Postbiotics are bioactive compounds produced as byproducts when probiotic bacteria ferment prebiotic fibres in the gut. It has anti-inflammatory and advantageous metabolic effects in addition to lowering the risk of chronic diseases and supporting brain health.

Some types of postbiotics are:

• Short-chain fatty acids
• Lipopolysaccharides 
• Enzymes
• Cell wall fragments
• Exo-polysaccharides
• Bacterial lysates (a mixture made from bacterial components)
• Cell-free supernatants (mixtures of compounds produced by bacteria and yeast)
• Other metabolites like vitamins and amino acids.
  
  

These postbiotics supplements are not readily available in the market, you can eat more prebiotic and probiotic food to increase postbiotics in your body. 

Let’s talk more about short-chain fatty acids. 

Short-chain fatty acids 

A fatty acid with less than 6 carbon atoms is a short-chain fatty acid. 95% of the SCFA contains acetate (C2) important for the production of energy and the production of lipids, propionate (C3) is mainly involved in releasing glucose in the liver and small intestine and butyrate (C4) is the energy source preferred for cells that line the colon. 

The fermentation of fibre in the colon results in the production of short-chain fatty acids. They provide the colon’s lining cells with energy.

According to the fibre content in the diet, microbiota composition and gut transit time (time taken for the food to travel through the digestive system and excretion) approximately 500-600 mmol of short-chain fatty acids are released in the gut. The largest production of SCFA is through the anaerobic fermentation of fibres. Large intestine microbiota use these metabolic pathways less than 1% to produce SCFAs.  

Unmetabolised SCFAs in colonocytes are carried into the portal circulation where they serve as the building block for hepatocytes’ energy production. 

The abundance of Akkermansia muciniphila (Gram-negative, anaerobic bacteria that breaks down mucus layers and inhabits human intestinal mucosa) is increased by an increase in SCFAs in the lumen. Increased production of mucin and mucus protects the integrity of tight junctions.

The B cells and the production of IgA and IgG are directly activated by the SCFAs. 

Through a variety of local effects, SCFAs protect against inflammation, produce mucus, maintain intestinal barrier integrity, and lower the risk of colorectal cancer—all of which contribute to improved gut health. 

Histone deacetylase (HDAC) activity is inhibited by SCFAs, which promote the acetylation of lysine residues found in nucleosomal histones across a variety of cell types and regulate systemic activities. This intracellular signalling mechanism has been identified in the peripheral nervous system, central nervous system, and stomach, along with related immunological tissue. 

All of the SCFAs have been linked to effects on brown adipose tissue activation, liver mitochondrial function regulation, whole-body energy balance, hunger control, and sleep regulation. 

Microbiota accessible carbohydrates 

Microbiota-accessible carbohydrates (MAC) are indigestible carbohydrates metabolised by the microorganisms. They are a subgroup of fermentable carbohydrates. In order to prevent intestinal dysbiosis and maintain the microbial ecosystem of the intricate digestive tract, these carbohydrates are essential. 

Due to their individual characteristics, each MAC can be used as a sensitive output microbiota modulator to regulate health and maintain host homeostasis. Non-communicable diseases (NCDs) are major health problems worldwide, MACs have shown a promising effect on the prevention of NCDs. 

MACs can come from the host or be ingested through a diet. Dietary MACs must be metabolisable by microbiota and can originate from a variety of sources, such as plants, animal tissue, or food-borne bacteria found in meals.

A microbial community becomes dependent on endogenous MACs obtained from the host, such as mucin glycans when dietary MACs are absent.

The gut microbiota is significantly impacted by the makeup of the food, especially by the availability of MACs. It is believed that dietary MAC-induced alterations in the diversity and composition of the microbiota are related to host health.

MACs sources

• L-arabinose and sucrose 
• Inulin and resistant dextrin
• Psyllium
• Β-glucan
• Resistant starch
• Pectic polysaccharides
• Galacto-oligosaccharides 
• Resistant dextrin
• Xanthan gum and fructo-oligosaccharides
  
  

Food sources

The main source of short-chain fatty acids is fibre, consuming legumes, fruits and vegetables that are rich in fibre increases the short-chain fatty acids in the body. The type and amount of fibre you consume influences the composition of the bacteria in your stomach, which influences the production of short-chain fatty acids. 

Types of fibre are:

• Inulin
• Fructo-oligosaccharides 
• Resistant starch
• Pectin 
• Arabinoxylan 
• Guar gum 

To improve your gut health 

• Consume a wide range of foods – A diversified microbiome promotes a sign of excellent gut health. Pulses, legumes, and fruits in particular are high in fibre and can have a potential role in the growth of beneficial Bifidobacteria.
  
  

• Consume fermented foods – Yoghurt, sauerkraut, and kefir are examples of fermented foods that contain good bacteria, mostly Lactobacilli, and can help lower the number of pathogenic species in the stomach.
  
  

• Avoid artificial sweeteners – Aspartame and other artificial sweeteners have an impact on blood sugar levels by increasing the growth of harmful bacteria like Enterobacteriaceae in the gut microbiome.
  
  

• Consume prebiotic food – Prebiotics promote the development of beneficial microorganisms. Apples, bananas, artichokes, asparagus, oats, and bananas are rich in prebiotics.
  
  

• Six-months of breastfeeding – Breastfeeding is crucial for the gut microbiome’s development. Breastfed infants had higher levels of beneficial Bifidobacteria than bottle-fed infants for at least six months.
  
  

• Consume plant-based diet – Vegetable-rich diets may help reduce inflammation, cholesterol, and pathogenic microbes like E. coli.
  
  

• Include a probiotic supplement – Live bacteria called probiotics can aid in the recovery of a healthy gut following dysbiosis. By “reseeding” it with beneficial bacteria, they do this.
  
  

• Consume antibiotics only when necessary – Weight gain and antibiotic resistance may be linked to the way antibiotics destroy many good and bad bacteria in the gut microbiome. Therefore, only use antibiotics when prescribed by a doctor.
  
  

Food for Gut 

High-fibre 

Consuming high-fibre food increases the production of short-chain fatty acids. These SCFAs have a positive effect on the gut. 

Food sources include:

• Legumes and pulses 
• Oats
• Quinoa 
• All vegetables and fruits  
• Almonds, walnuts, and pistachios
  
  

Fermented food 

The highest source of probiotics is fermented food. These fermented foods undergo controlled microbial growth, the food is broken down during the anaerobic process which helps with easy digestion. They contain beneficial bacteria. 

Food sources 

• Kimchi 
• Yoghurt 
• Pickles 
• Kefir 
• Sauerkraut
  
  

Collagen rich food 

Consuming food will help boost collagen and may have a beneficial effect on the gut. Bone broth and salmon skin have beneficial effects on gut health. 

Collagen-boosting food source 

• Citrus fruits
• Meat
• Broccoli 
• Eggs
• Nuts
• Shellfish 
• Berries 
  
  

Conclusion 

Maintaining good gut health is important for general well-being and weight loss. A healthy gut microbiome influences everything from your mood to cognitive function. Follow healthy balanced, high-fibre foods, and fermented foods to increase the beneficial bacteria in your gut. Keep in mind that your stomach is your “second brain,” and taking care of it with a healthy diet can have a significant positive impact on both your physical and mental health.

Kripa N,
Senior Clinical Dietitian, Simplyweight