Informed dietary choices, regular physical activity key to healthier life

The human intestine is essential for digesting food, absorbing nutrients, and excreting waste. The intestine extends through the duodenum to the small intestine and large intestine, linking the colon to the outlet anus, where fecal excretes are being passed out.

The intestine plays significant role in health and disease, to the extent that a little disruption of the intestinal content could result in states of metabolic disorders. These intestinal contents are made up of trillions of microorganisms of which 99 peer cent are the bacteria. The intestine of healthy human was estimated to hold 38 trillion bacteria, together with the 1 per cent of other microorganisms (i.e.fungi, protozoa and viruses) are collectively called intestinal microbiota.

The relative distribution of intestinal bacteria is unique to an individual, partly owing to strain-level diversities and differences in microbial growth rates and in structural variants within the microbial genes, and partly owing to influence from the considerable inter-individual variation in the host genetics and environmental exposures such as diet, and lifestyle.

The overall genetic composition of these intestinal microbiota is referred to as intestinal microbiome. The number of genes in the intestinal microbiome is 150- to 500-fold more than in human DNA. Imbalances or alterations in the intestinal microbial composition or activity, also called Intestinal dysbiosis.

The mode of birth and access to breastfeeding shape the infant gut microbiota, and it matures gradually during childhood in response to environmental exposures. Thereafter, the intestinal microbiota remains relatively stable in late childhood, adolescence and adulthood until a decline in diversity occurs as a result of environmental exposures and host genetics. Breastfeeding, food and water security are major protective factors against malnutrition and are crucial factors in the maturation of the healthy gut microbiota.

Globally, malnutrition affects160 million people and is the leading cause of death in children under the age of five years. Early loss of Bifidobacterium longum and Bifidobacterium pseudolongum, two key members in mother milk, represents some of the first disruptions in the intestinal dysbiosis of severe acute malnutrition (SAM). The loss of the healthy mature anaerobic gut microbiota gradually leads to a deficiency in energy harvest, immune responses and vitamin synthesis, and links with chronic malabsorption, diarrhea and systemic invasion from pathogenic bacteria.

The diet is regarded as one of the key drivers for the differences in gut microbiota between people and environmental exposures and lifestyles. Whole diets as well as food components (protein, fat, carbohydrates, polyphenols,) influence the total bacteria community as well as the relative abundance of certain species.

Food processing and preservation reduces the intake of commensal, food-associated microbes, whereas fermented foods enrich specific bacteria that transiently colonize the gut.

Plant protein diet like whey, pea, bean nourishes the beneficial bacteria. However, an animal protein-based diet usually also means a higher fat intake. Fruits, seeds/nuts, vegetables, tea, cocoa products, and wine contains polyphenols which increases the relative abundance of beneficial bacteria. Fruit polyphenols work against Staphylococcus aureus and Salmonella typhimurium which are disease causing (pathogenic) bacteria. Food delivering prebiotics are soybean, chicory roots, raw oats, unrefined wheat, unrefined barley, as they contain carbohydrates which are not digested in the small intestine but are fermented in the large intestine by anaerobic colonic microbiota to beneficial metabolite (i.e. short chain fatty acids).

The microbiota produces signaling molecules and metabolites that influence several intestinal functions: visceral-sensing, motility, digestion, permeability secretion, energy harvest, mucosal immunity, and barrier effect. These products are also transported to various organs affecting their functionality: brain (cognitive functions), liver (lipid and drug metabolism), and pancreas (glucose metabolism). Imbalances or alterations in microbial composition or activity, also called Dysbiosis can influence health and is implicated in various diseases, such as obesity, type 2 diabetes, asthma, allergies and inflammatory bowel disease.

Obesity results from the accumulation of excess fat in the adipose tissue. Causes include behavioral and environmental factors, such as excessive consumption of energy-dense foods and a sedentary lifestyle. But also, intestinal microbiota turned out to take part in the development of obesity. Microbiota from obese individuals has an increased capacity to harvest energy from the diet. The elevated harvested energy causes a state of imbalance between energy intake and energy expenditure, a resultant model for the development of obesity. Microbiota also influences the host’s lipid metabolism by increasing fat deposition and storage in adipose tissue, liver, and/or muscle.

Diet is one of the critical factors in progression of obesity and is profoundly linked to intestinal microbiota composition. Nutrient intake and eating habits directly influence the composition, diversity, and metabolism of intestinal microbiota.

Furthermore, the composition and functionality of intestinal microbiota respond quickly to changes in dietary composition. Interestingly, a healthy dietary pattern related to intestinal microbiota profiles exerted protective effects against development of diabetes in obese individuals. Therefore, a balanced diet is required to maintain the composition and proper function of the intestinal microbiota, and this have the potential to improve the human health condition.

Aside diet, lifestyle, physical activity and exercise acutely promote a more anaerobic intestinal environment potentially promoting increased inhabitation of anaerobic bacteria. Exercise can also influence the gut’s mucus layer, a critical barrier between microbes and the gut lining; as well as gut motility which can alter GI transit time, potentially impacting microbial habitats and their nutrient availability. Resistance training increases abundance of selected SCFA producers and microbial metabolic pathways and improves cardiometabolic health.

In conclusion, the human intestine is a dynamic and essential part of our overall health, influenced significantly by diet, lifestyle, and environmental factors. From birth through adulthood, maintaining a balanced gut microbiota is crucial for preventing diseases and promoting well-being. By adopting a balanced diet and an active lifestyle, individuals can support their gut health, thereby enhancing their overall health and quality of life. This underscores the importance of informed dietary choices and regular physical activity as pivotal strategies for maintaining a healthy microbiota and, consequently, a healthier life.

Adepoju is a Gut Microbiome Specialist/ Postdoctoral Research Fellow at University of Missouri, Columbia, USA.