The importance of protein digestion in maintaining gut health

10/03/2025

Proteins are one of the cornerstones of animal nutrition and play a role in many critical processes. In addition to achieving the targeted performance in farm animals, they are the basic element needed in the synthesis of hormones and enzymes that regulate physiological processes and in the strength of immune system functions.

The relationship between protein digestion and microbiota

Undigested proteins are an important source of nutrition for pathogenic microorganisms. They can cause pathogenic microorganisms to increase in number and become dominant in the intestinal microbiota in a short time. This situation generally affects the intestinal microbiota negatively and causes the microbiota balance to be disrupted, which is defined as “dysbacteriosis”.

Beneficial bacteria such as Lactobacillus sp. and Bifidobacterium sp. cannot use poorly digested proteins as a source of nutrition as quickly as pathogenic bacteria. Therefore, in a feeding model where there is a poorly digested or poor quality protein source, pathogenic bacteria quickly increase in number and become dominant in the intestinal microbiota. Harmful microbial metabolites synthesized by pathogenic microorganisms during the fermentation of proteins cause both the suppression of beneficial bacteria and the initiation of inflammatory reactions in the mucosa. At the same time, these metabolites damage epithelial cells and slow down the formation of new cells. As a result, they cause the physiological functions of the selectively permeable intestinal barrier, which is a physical element of mucosal immunity, to deteriorate. This increases the risk of “leaky gut syndrome” and causes antigens to enter the blood.

Healthy gut–Strong liver

Protein digestion begins in the stomach and small intestine, where it is expected that they will be completely broken down. However, in cases such as low-quality feed materials, insufficient enzyme activity or rapid stomach-intestinal transit, some of the proteins can reach the large intestine without being digested. When undigested proteins reach the large intestine, microbial fermentation of the proteins begins. During this process, harmful microbial metabolites such as ammonia, indole, skatole, and hydrogen sulfide are formed. It is not correct to think that these metabolites will cause negative effects only in the large intestine locally. First of all, these metabolites spread throughout the entire digestive system and damage the intestinal barrier. In this condition known as “Leaky Gut Syndrome”, microorganisms and the harmful metabolites they produce, as well as mycotoxins in consumed feed, easily reach the liver.

Ammonia damages the intestinal mucosal epithelium and slows down cell regeneration. As ammonia levels increase, it causes inflammation in the intestine and the deterioration of the barrier function. The energy expenditure of the liver to metabolize ammonia is a separate dimension, which reduces the general efficiency of the animal.

Indole and skatole, which are degradation products of proteins formed by microorganisms, can cause toxic effects in the gut, liver and all other organs. Skatole in particular triggers mucosal inflammation and damages the selectively permeable intestinal barrier. When produced in large quantities by microorganisms, performance loss and immunosuppression occur.

Another metabolite formed as a result of fermentation of indigestible proteins by pathogenic microorganisms is hydrogen sulfide compounds. These compounds have high toxicity for intestinal epithelial cells. So much so that they prevent mucosal epithelial cells from producing mucus. Inflammatory reactions will occur rapidly in the mucosa that has lost its physical barrier. In such a case, even if the protein source is of high quality, proteins will not be digested sufficiently in the intestine, whose physiological functions are weakened due to inflammation, and will continue to form a new ground for pathogenic microorganisms.

Indigestible proteins cause energy loss

Indigestible proteins act directly as “immunostimulatory” molecules, causing the immune system to spend energy in a way similar to the reaction it shows to pathogens. If the stimulus is not eliminated in the ongoing process, that is, if the indigestible protein source is continuously taken, it can cause the onset of mucosal inflammation in the digestive tract. In fact, the energy that should be transferred to the yield share is made available to the immune system to a very large extent, depending on the course of the mucosal inflammation.

The misuse of energy negatively affects all living organisms. At best, animals reduce the energy share that they should transfer to the yield share. Moreover, it is almost inevitable that metabolic problems will be triggered and sensitivity to pathogens will increase. So much so that this situation is first reflected in performance parameters.

The fermentation of undigested proteins in the intestine causes the microbiota balance to be disrupted, inflammatory reactions to form in the intestine and the loss of barrier functions. In this case, in order to support the optimal performance and health of animals, high protein digestibility should be provided, intestinal health should be prioritized and feed additive strategies should be organized accordingly.

Scientific research studies have proven that Sangrovit® is an unconditional supporter in controlling digestive system inflammation in farm animals, improves protein metabolism and protects liver health.

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