- Microbiome and he alth
- Changes in the microbiome with age
- How does lifestyle affect the microbiome?
- How does diet affect the microbiome?
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Diet has a direct impact on the composition of the microbiome, and the composition of the microbiome in turn has a direct impact on he alth. Not only nutrients affect the biodiversity of the microbiome, but also lifestyle (smoking, stress, inactivity), which is often ignored. How do proteins, carbohydrates, fats, polyphenols and artificial sweeteners affect the microbiome?
The relationship between diet and the composition of the microbiome has been observed for several decades. Some of the nutrients go to the large intestine unchanged, therefore what we eat has a large impact on the composition of the intestinal microbiota. The purpose of nutrition in the context of maintaining a proper bacterial balance is to increase the proportion of commensal bacteria in the microbiome, and to reduce the number and diversity of pathogenic bacteria.
Microbiome and he alth
It is said that there are 10 times more microorganisms in the human digestive tract than there are cells. Without the intestinal microbiome, a person cannot live he althy.
It is known today that the variety and quantity of gut bacteria affects a whole range of life processes and contributes to many diseases. Bacteria produce numerous substances, some of which are nutritional and others toxic. They are important both for human metabolism and immune processes.
Intestinal dysbiosis, a condition in which the balance between the amount of desired and harmful bacteria is disturbed, is both a symptom and a cause of disease.
Pathogenic bacteria overgrowth is important in:
- autoimmune diseases,
- autism,
- inflammatory bowel disease,
- mood disorders,
- diabetes
- Is obesity.
Changes in the microbiome with age
The first moment of life that determines the composition of the microbiome is childbirth. Natural childbirth is responsible for a greater number of gut bacteria in newborns and therefore is more beneficial for the development of the immune system than delivery by caesarean section.
The commensal bacteria Lactobacillus and Bifidobacterium dominate the microbiome during the breastfeeding period.
Expanding the diet and eating solid foods requires the presence of a whole range of different bacteria, so naturally the amount of Lactobacillus and Bifidobacterium in the microbiome decreases, andother microorganisms. This is called functional maturation of the microbiome.
As long as a person does not develop diseases that significantly alter the microbiome, it is relatively constant until old age.
Constancy does not, however, mean that it is similar to other people's microbiome. Microbiomes can be radically different depending on factors such as genetics, living environment, nutrition, smoking, etc. With age, the amount of Bacteroidetes in the microbiome decreases and Firmicutes grows.
How does lifestyle affect the microbiome?
Lifestyle is the most ignored aspect of microbiome balance and he alth. Smoking is one of the most important lifestyle factors that cause intestinal dysbiosis.
How is cigarette smoke related to bacteria in the colon ? Airborne toxic particles can reach the large intestine through mucociliary cleansing of the lungs, which has a direct effect on the microbiome and increases the number of pathogenic bacteria, Bacteroides prevotella. Similarly, the increased pollution of the environment associated with increasing industrialization and the growth of cities.
Another very important factor in changing the microbiome is stress . Stress affects the gut-brain axis, which acts on two levels - hormonal and neuronal.
As a result of chronic stress, the number of commensal bacteria of the Lactobacillus genus decreases, which in turn favors the overgrowth of pathogenic bacteria.
Other factors that change the microbiome are :
- disturbed circadian rhythm, e.g. due to shift work,
- long journeys,
- personal hygiene,
- sanitation.
How does diet affect the microbiome?
The diet affects the composition of the microbiota, as some of the nutrients go to the large intestine unchanged. From the average European diet every day, about:
- 30 g fiber and other carbohydrates,
- 5 - 15 g protein
- and 5-10 g of fat.
Various other dietary ingredients, including polyphenols, catechins, lignin, tannins, and micronutrients, also nourish the microbes in the colon.
About 90% of food polyphenols avoid digestion and absorption in the small intestine. All these nutrients metabolized by the microbiome have a significant impact on the population and activity of the microbes.
Protein
Dietary protein is the main source of nitrogen for bacterial growth in the large intestine and is essential for the absorption of carbohydrates and the production of beneficialsubstances such as short chain fatty acids. Therefore, the presence of protein and carbohydrates in the colon can contribute to gut he alth.
However, unlike carbohydrates, the fermentation of protein sources by the microbiota produces a much greater variety of gases and metabolites, and increasing nitrogen availability can also increase the amount of putrefaction products.
The effects of protein consumption on the gut microbiome were first seen in a 1977 study. Since then, comparative analyzes have been carried out on different populations, e.g. with Italian children (high protein diet) and African rural children (carbohydrate-based diet), as well as studies in which participants were fed diets with different proportions and origins. proteins.
Both the protein content in the diet and its source - vegetable or animalare important for the diversity and quantity of intestinal bacteria. Animal protein affects the microbiota differently than plant protein. Large amounts of animal protein, mainly from red meat, should be considered as deteriorating the composition of the microbiome. On the other hand, plant-derived protein, even in high concentrations, increases the amount of commensal intestinal bacteria.
Research shows that the consumption of protein from vegetarian sources, such as peas, increases the concentration of bacteria from the genera Bifidobacterium and Lactobacillus, which are of key importance for the balance of the microbiome and human he alth.
Whey protein (very often used in sports protein) works in the same way as opposed to animal protein-rich foods such as meat, cheese and eggs.
In addition, whey protein reduces the amount of pathogenic bacteria Bacteroides fragilis and Clostridium perfringens.
Very important for the microbiome and overall he alth is the fact that the consumption of protein from plant sources promotes a higher concentration of short-chain fatty acids in the intestine. They are the main source of energy for intestinal epithelial cells, improve their nutrition, regeneration and tightness of intercellular connections, and at the same time have anti-inflammatory properties.
The consumption of animal protein is associated with a lower concentration of commensal bacteria in the large intestine, and a higher concentration of pathogenic bacteria, e.g. from the genera Bacteroides, Alistipes and Bilophila. Less butyric acid is observed in the stool of people on an animal protein diet, which shows that this type of diet (high in protein, low in carbohydrate) hinders the production of SCFAs in the intestine.
As far as not possible on the basis of the currently availableknowledge to state that high consumption of animal protein causes specific diseases, research shows correlations that should definitely be taken into account:
- high animal protein intake is associated with a higher risk of inflammatory bowel disease,
- in people whose diet was based on animal protein, a higher concentration of TMAO - a pro-atherogenic molecule, contributing to the production of atherosclerotic plaque and increasing the risk of heart disease was observed,
- a large amount of plant-based protein in the diet reduces the concentration of inflammatory markers in the body.
Effect of dietary protein on the microbiome
| Vegetable protein | Animal protein | |
| Effect on commensal bacteria | Increase in the amount of bacteria (Bifidobacterium, Lactobacillus) | Bacterial decline (Bifidobacterium) or no effect |
| Effect on pathogenic bacteria | Decrease in the amount of bacteria (Bacteroides, Clostridium) | Increase in the amount of bacteria (Bacteroides, Alistipes, Bilophila) |
| He alth effect | Increased SCFA concentration, increased intestinal epithelial integrity, increased secretion of Treg immune cells, decreased inflammation | Increase in TMAO concentration, decrease in SCFA concentration, increased risk of intestinal diseases and heart disease |
Fat
The composition of the microbiome depends on the quantity and quality of fat in the diet, but its quality is much more important. Sometimes you can find a simplified approach that says that a high-fat diet negatively affects the microbiome, and a low-fat diet favors it, but after delving into the details, the relationship is not so simple and obvious.
Fats that negatively affect the microbiota and increase the proportion of pathogenic bacteria include trans fats from processed, deep-fried and fast food foods, and saturated fats that contain long-chain fatty acids.
A typical Western diet rich in ready meals, red meat, snacks, sweets and fast food, including saturated and trans fats, negatively affects the microbiome, causing more pathogenic bacteria to proliferate.
Saturated fat in the diet can increase the number of pro-inflammatory gut microbes by stimulating the formation of taurine-conjugated bile acids that promote the growth of pathogens. The presence of these bacteria is associated with increased inflammation of white adipose tissue, increased immune system response anddecreased insulin sensitivity.
At the same time, research shows that a high-fat diet, but rich in unsaturated vegetable fats, does not change the qualitative and quantitative composition of the microbiome, and a diet rich in fish fats - improves its composition by increasing the proportion of commensal lactic acid bacteria.
The trend for the effects of fat consumption on the microbiome is exactly the same as for its effects on overall he alth. Trans fats (primarily) and saturated animal fats change the microbiome to the detriment of the host, vegetable fats are neutral to the host, and fish fats improve the composition of the microbiome.
Carbohydrates
Carbohydrates are distinguished between digested and non-digested in the digestive tract. Digestible carbohydrates are starch and simple sugars - glucose, fructose as well as sucrose and lactose (the latter two are chemically disaccharides, but in terms of nutrition they are treated as simple sugars). On the other hand, non-digestible carbohydrates are classified as fiber. The consumption of all types of carbohydrates is conducive to the proper microbiota.
Carbohydrates are the primary source of energy and carbon for bacteria in the large intestine. Carbohydrates are fermented into organic acids, which provide energy to other bacteria, intestinal epithelium and peripheral tissues.
Short chain fatty acids are the major end products of carbohydrate fermentation that help lower the pH in the colon, thereby inhibiting the growth and activity of pathogenic bacteria.
Studies have shown that people taking glucose, fructose and sucrose respond with an increased proportion of the commensal bacteria Bifidobacterium, and a reduced proportion - of pathogenic bacteria of the genus Bacteroides.
Lactose is an interesting and demanding component of food, which is commonly regarded as irritating to the intestines. It turns out that lactose also works in the same way as other simple sugars, and also reduces the amount of pathogenic Clostridia species in the microbiome.
Fiber, or non-digestible carbohydrates, has a very good effect on the microbiome and is one of the prebiotics. A diet low in fiber results in a reduced diversity in the microbiome, and a high fiber diet increases the diversity of species living in the gut and the amount of short-chain fatty acids produced by bacteria that are essential for the proper functioning of the gut.
Dietary fiber is associated with greater numbers of commensal bacteria, mainly bifidobacteria and lactic acid bacteria.
Artificial sweeteners
Currently, artificial sweeteners are considered more harmful to the body than glucose and sucrose, whichthe consumption was to limit. They also negatively affect the microbiome, causing dysbiosis (increased share of pathogenic bacteria, reduced share of commensal bacteria) and its numerous consequences, including:
- digestive system diseases,
- allergies,
- metabolic diseases
- Does cardiovascular disease.
Polyphenols
Polyphenols are a numerous group of bioactive plant compounds with antioxidant activity. They include:
- catechins,
- flavonols,
- flavones,
- anthocyanins,
- proanthocyanidins
- and phenolic acids.
The sources of polyphenols are:
- vegetables,
- fruit,
- cocoa,
- tea
- or red wine.
They have a strong effect against pathogenic bacteria, which is also responsible for a beneficial effect on the intestinal microbiome. As a result of the consumption of polyphenols, the number of pathogenic bacteria, mainly Clostridia, decreases, and the number of commensal Bifidobacterium increases.