VERIFIED CONTENTAuthor: Dominika Wilk

Proper intestinal bacterial flora and a tight intestinal barrier are not only a guarantee of he alth, but also a better metabolism. If you are a person who, despite exercise and a low-calorie diet, cannot lose unnecessary kilograms, take a look at your intestinal microflora. Perhaps this is where the main source of overweight and obesity problems lies.

The intestinal microbiotaconsists of over 10 billion commensalic, symbiotic and pathogenic microorganisms found in the human intestine. In turn,intestinal microflorais the set of all genes of these microorganisms that inhabit the human body. It turns out that disturbed microbiota may be related to obesity.

What is the gut microbiota and microflora? What does it consist of?

If you want to divide the intestinal microflora, you can distinguish commensal microflora in it, which makes up 30% of the entire flora and is its core, so it does not change throughout our lives. In turn, 70% of the intestinal microflora is transient flora, which, along with the food content, passes through the body and is later excreted from it.

Taking into account the influence of microorganisms inhabiting the human digestive tract on its functioning, the intestinal microflora can be divided into:

  • Absolutely pathogenic, it causes disturbances in the digestive tract, mainly due to the increased production of toxins. This type of flora includes, for example, such microorganisms as: Salmonella, Shigella, Psudomonas.
  • Relatively pathogenic, the negative influence of which can be felt during digestive disorders. It includes, for example, Klebsiella, Proteus, Escherichia.
  • Beneficial that blocks the development of pathogens and stimulates many important functions of the digestive system, e.g. Lactobacillus, Bifidobacterium.

Importantly, both the absolutely pathogenic and beneficial flora constitute only 10% of the total microflora. The remaining 90% is relatively pathogenic flora, on which the good functioning of the organism depends and whose stability must be the most important.

What keeps our intestinal microflora in balance is the correct proportions between the individualbacteria, both beneficial and pathogenic, and the diversity of flora.

What are the functions of the gut microbiota?

The gut microbiota plays a number of important roles in the body. First of all:

  • It inhibits the multiplication of pathogenic bacteria and prevents their further growth.
  • Contributes to the digestion of various nutrients.
  • Supports the breakdown of toxins.
  • It is necessary for the production of SCFA (short chain fatty acids), which are the most important source of energy for colonocytes (colon cells).
  • Prevents the development of allergies.
  • Supports the immune system.
  • It is associated with the production of vitamins such as: vitamin K, B12, b1, B6, or folic acid).
  • Cares for the proper condition of human skin and nails.
  • Has a positive effect on mood (with dysbiosis people tend to be depressed, low mood).

What is the relationship between the gut microbiota and obesity?

The effect of obese gut microbiota was noticed after a breakthrough study on mice by Turnbaugh et al. In this study, mice devoid of bacterial flora (because they were bred in completely sterile conditions) were transplanted with the microflora of obese mice. The sterile mice were lean at the start of the study.

However, just 2 weeks after the flora transplantation, their fat mass increased by as much as 60% with the same diet. This made researchers think, as it meant that not only the amount of food itself was important, but also how the bacteria used it.

It was then discovered that some genes coding for enzymes caused bacteria to break down indigestible polysachards, thus increasing the caloric pool obtained. This resulted in an increase in the daily energy pool, e.g. by an additional 200 kcal.

Another reason for the different metabolism in obese compared to lean people is the different proportion between the species of bacteria inhabiting the intestines. There are 9 species of bacteria in the lower digestive tract, 98% of which belong to 4 main types:

  • Firmicutes (64%)
  • Bacteroidetes (23%)
  • Proteobacteria (8%)
  • Actinobacteria (3%)

As it has been discovered, an imbalance between the most numerous of them, i.e. Firmicutes and Bacteroidetes, may lead to an increased risk of weight gain. This is confirmed by the results of the study by Ley et al., Where the stool composition of 12 obese people was analyzed, showing the advantage of Firmicutes over Bacteroidetes compared to the control group (lean people).

After dieting in obese people(one group received a carbohydrate reduction diet, the other group received a fat reduction diet), it turned out that as weight decreased, there was an increase in Bacteroidetes. At the beginning of the study, they accounted for only 3% of all intestinal bacteria, and at the end - 15%.

The conclusions of this study are that Firmicutes are likely to promote more energy from food, and that dietary modification may lead to the growth of these bacteria, which will promote weight loss.

The job of the microbiome is to break down fiber into short-chain fatty acids (SCFA), and this is a very positive phenomenon. However, it has been noticed that obese people produce more of these acids than lean people. This leads not only to the above-mentioned greater energy supply, but also to stimulating lipogenesis in the liver. SCFA delivered to the liver are involved in the synthesis of triacylglycerols, and these in turn are stored in adipose tissue cells.

This accumulation of adipose tissue is facilitated by an additional mechanism related to the intestinal microbiome of obese people, namely inhibition of the expression of FIAF (fasting-induced adipocyte factor) - a tissue factor induced by starvation.

Lowering this expression increases the activity of lipoprotein lipase, and thus promotes fat accumulation.

Fat tissue in obese people, especially visceral tissue, causes inflammation.

This leads to the production of numerous pro-inflammatory cytokines, interleukin 1, interleukin 6 or TNF. The most dangerous, as it increases the risk of weight gain and metabolic disorders, is TNF, which changes the structure of insulin and leptin receptors. Insulin is the hormone that regulates blood sugar, and leptin is the satiety hormone.

In order for them to work, they must bind to the appropriate receptor, and they must match each other perfectly, like a key to a lock. Every little change that would take place in the structure of a hormone or receptor would make them fail to connect. And this is exactly what happens when TNF starts working.

It causes that the hormone insulin and leptin cannot be active because they do not bind to the receptor whose structure has been altered. This causes an imbalance in the insulin metabolism, as well as leads to a lack of satiety, and thus to a greater consumption of food.

Modification of the gut microbiome in obese people

Although the composition of the intestinal microflora is as individual as a fingerprint and may predispose us to certain diseases, such as obesity, we canmodification. It is possible mainly thanks to targeted probiotic therapy, administration of prebiotics, antibacterial drugs, or by changing the diet.

Probiotics

Probiotics are live bacteria cultures that have a beneficial effect on human he alth. Their intake may, in some cases, modify the intestinal microbiota, and thus reduce disorders caused by an improper diet or lifestyle. In order to bring measurable benefits, however, they must be carefully selected according to the problem, diseases accompanying obesity, or even gender.

As shown by the research of Lee et al., Administering a probiotic with the Lactobacillus rhamnosus PL60 strain to mice that remain on a high-fat diet reduces their fat cells after 8 weeks.

However, since in adult humans fat cells can only change in size but cannot be reduced, this mechanism will not work. Nevertheless, it shows great possibilities of modifying the bacterial flora with a probiotic and gives hope for preventing obesity precisely by changing the microbiome with the help of targeted probiotic therapy.

Another study that shows that by modifying the microbial flora, it is possible to change the metabolism in humans is one that meets the requirements of evidence-based medicine, in which 87 patients with visceral obesity and a BMI of 24.2-37 participated, 0 kg / m2.

For 12 weeks they received the Lactobacillus gasseri SBT2055 strain (10 to the power of 10 CFU / d) and after that time both their body weight and BMI decreased, the amount of visceral adipose tissue and the amount of adipose tissue decreased. under the skin, and the circumference of the hips and waist decreased.

This shows that the use of probiotics can have a beneficial effect on reducing metabolic disorders and regulating body weight.

Probiotics do not always reduce the total body weight. Sometimes there is only a decrease in the BMI itself, which in the case of significant obesity is of great importance anyway, because it brings visible, positive he alth effects. This is what happens when supplemented with Lactobacillus gasseri BNR17.

First of all, it lowers the BMI index and hip circumference, but it has a much less impact on the overall reduction of body weight or the reduction of adipose tissue. This is confirmed by the results of studies carried out on 57 volunteers, divided into the group consuming the probiotic and the placebo group.

Some probiotics work differently on men than on women. In studies involving people of both sexes who were given the strainLactobacillus rhamnosus CGMCC1.3724, the women had better results in terms of weight loss and subsequent maintenance of the effects.

When using probiotics in obese people, you need to take into account not only the overall weight loss, but also the reduction of adipose tissue itself, which, as it is known, generates inflammation and is the cause of intestinal dysbiosis. Therefore, obese patients who want to bring their intestines to a state of eubiosis (equilibrium), who want to reduce the constant inflammation in the body, should be interested in the results of studies on the Bifidobacterium breve B-3 strain.

People with BMI between 24-30 participated in this study. They were divided into the probiotic group and the placebo group. After 12 weeks, the results of supplementation were checked and it turned out: in the group receiving the above-mentioned bacterial strain there was a greater decrease in fat mass compared to the control group.

In turn, there were no significant differences in overall weight loss.

Prebiotics

Prebiotics are a breeding ground for intestinal bacteria, thanks to which they can grow and show positive activity, e.g. increase the amount of short-chain fatty acids (SCFA) produced, which improve the composition of the intestinal epithelium.

In addition, prebiotics are involved in the regulation of the body's fat and sugar metabolism and sensitize tissues to insulin.

They also increase the production of mucus that protects the intestines, namely mucins, as well as support the removal of toxins generated, for example, by the bacteria themselves. Their presence in the diet of obese people is therefore necessary to properly modify the intestinal microbiome.

The studies conducted so far on the impact of prebiotics on the microbiome of obese people show that they primarily have a positive effect on the carbohydrate metabolism.

In addition, a single cross-over study by Garcia et al (participants alternating treatment with a prebiotic and a placebo) shows that a prebiotic such as arabinoxylan (the dietary fiber found in the shell of cereal grains) reduces both fasting and fasting blood glucose levels. and after a meal and lowers the postprandial ghrelin (hunger hormone) index, as well as lowers the concentration of triglycerides in the blood after 6 weeks of its use.

Diet

Due to the fact that the composition of the intestinal microflora is also influenced by the consumed diet, it can be assumed that its modification may lead to an increase in the amount of bacteria conducive to weight reduction.

Some studies show that switching from a high-fat diet to a low-fat diet is associated with an increase inBacteroidetes that promote weight loss. Therefore, replacing the fat-rich diet preferred by obese people with a menu with less fat would help reduce body weight.

A similarly beneficial modification would be made by replacing the typical unhe althy, high-protein, low-fiber Western diet with a low-fat diet, dominated by essential fatty acids, with moderate amounts of protein, and high in fiber.

The former is one of the causes of intestinal dysbiosis, which leads to inflammation and the secretion of TNF that inhibits the activity of leptin and insulin. This, in turn, promotes metabolic disorders, increased food supply and the deposition of adipose tissue.

The second of these diets, on the other hand, supports the maintenance of eubiosis (equilibrium) in the intestines, which in turn may reduce the risk of inflammation and will have a positive effect on body weight.

Category:

Obesity