MAINTAINING THE MICROBIOME AS ADULTS
Is the gut microbiome unique to each person?
Everyone has a unique gut microbiome. But herein lies the problem. It’s difficult for scientists to determine a “normal” or “healthy” pattern of microbes because every body’s microbiome is different – even in identical twins! This makes working out what a healthy microbiome looks like challenging.
Diet and Nutrition for Improving the Microbiome
Feeding the gut microbiome is essential for its longevity. The types of food consumed has a significant impact on the population that survives.
The typical Western diet is high in fat and low in fibre and has been linked to a decrease in overall bacteria and of the beneficial species.
High fibre diets are more beneficial as this will provide good nutrients to the gut microbiome, increase the bacterial richness (the number of distinct species in the community) and boost production of short-chain fatty acids.
People can eat their way to good gut health. To do that, people must expand their food horizon.
For adults, diet is the most powerful influence on the microbiome. By regulating the food items consumed and in what quantities, it is possible to manipulate the population densities of the different microflora.
The consumption of fibres (or prebiotics) can proportionately increase the diversity of these probiotic bacterial species in the gut. Bacteria metabolise these fibres, and the fermentation results in the production of short chain fatty acids, which nourish the gut barrier, enhance immunity, and reduce inflammation.
Vegetables, herbal tea, fruits, red wine, and dark chocolate can come in handy in regaining the lost bacterial diversity. The essential components in these food items are the polyphenols—which have unique properties—the most important being their antioxidant characteristic.
The Gut Project is a citizen science project based in the UK. The project is an open-source crowd funded project that relies on volunteers sending their faecal samples in the post for analysis. The key finding in the project is that microbial diversity is key. A diet rich in prebiotics seems essential.
Eating a wide-range of plant-based foods such as seeds, herbs, spices, nuts, legumes, fruits, and vegetables – all provide fuel for microbes. Conversely, sugar, antibiotics and processed foods decrease the number and diversity of human microbiota.
Lifestyle and Other Factors
There are a variety of other factors that can influence the gut microbiome including:
- Exposure to pathogens – colonisation by pathogenic bacteria can induce inflammation in the GI tract which can destabilise the gut microbiome or outcompete the commensal bacteria causing further illness.
- Age – as people get older, their microbial diversity decreases and this reduction in diversity is correlated with nutritional status, increased inflammation, and frailty.
Research now shows that long-living people (including those that live to 100 years) exhibit increased gut microbial diversity. If people want to live long lives, then it is critical to nourish gut microbes.
- Stress and Anxiety – stress and anxiety can affect gut motility, visceral perception, GI secretion and intestinal permeability. These can in turn negatively alter the composition of the gut microbiome.
- Medication – medications such as antibiotics and proton pump inhibitors (typically prescribed for acid reflux), can disrupt or diminish taxonomic diversity which can persist over time.
THE GUT MICROBIOME EFFECT
The microbes in the gastrointestinal tract have tremendous potential to impact human physiology, both in health and in disease. These microbes contribute metabolic functions, protect against pathogens, educate the immune system, and, through these basic functions, directly or indirectly affect most of the physiological functions of the body.
Contribution to Metabolic Function
The gut microbiome can be thought of as an additional organ, or “metabolic organ” due to the role it plays in metabolic function. Food that is ingested is the source of most precursors for important metabolites.
Yet diet also affects the diversity and population size of the gut microbiome. This creates a complex relationship between food, microbiome, and nutrient availability in the host.
The microbiome also produces metabolites, called microbial-derived metabolites, which are necessary for human health. Different species produce different metabolites. When the microbiome is out of balance, or dysregulated, the host may experience adverse effects, including an increased likelihood of:
- metabolic syndrome
- inflammatory disorders
- difficulty with digestion of certain food types
- weight gain and/or obesity
- decreased energy
- insulin resistance
Research shows that the gut microbiome plays an important role in developing the lining of the gut. This, in turn, affects gut motility and how well the gut can extract calories and other nutrients from food.
The microbiome is also responsible for breaking complex sugars (polysaccharides) into smaller, digestible molecules in the distal intestine.
The gut microbiome also plays more complex roles, including signalling, which affects other processes within the body. For examples, when some species gut bacteria ferment fibre, they produce short-chain fatty acids.
These short-chain fatty acids interact with special receptors (G-protein-coupled receptors) which regulate how much insulin is produced. This is part of the regulatory process for energy metabolism.
Researchers posit that when this pathway is affected due to an imbalance in the microbiome, the knock-on effects may contribute to insulin resistance and the development of type II diabetes mellitus.
Species which are essential parts of metabolic pathways are generally referred to as keystone species.
