Butyric acid belongs to the group of compounds called short-chain fatty acids (SCFas). Along with acetic and propanoic acid, they constitute over 80% of the total pool of SCFas found in the intestines [1]. SCFas, with butyrate at the forefront, play an extremely important role in maintaining intestinal homeostasis. The butyrate anion is easily absorbed by intestinal cells, which use it as a primary source of energy [2]. Moreover, butyric acid is responsible for, e.g. the regulation of colonocyte proliferation and apoptosis, normalization of the intestinal passage, and exerts considerable anti-inflammatory and immunoregulatory effects [3]. Such a comprehensive action makes butyric acid an extremely versatile compound.
Versatile compound
The application of sodium butyrate is extremely wide. Let's take a closer look at the mechanism of action of this compound concerning specific factors:
- Anti-inflammatory effect. Chronic inflammation of varying severity is a very common bowel disease. Sodium butyrate reduces the production of TNF-α (Tumor Necrosis Factor-α) and other pro-inflammatory cytokines. This is most likely due to the reduced activation of NF-κB [4].
- Immunomodulatory effect. Short-chain fatty acids are considered to be a kind of mediator between intestinal microbiota and the immune system. The significance of a good condition of our microbiota in the context of the proper functioning of the immune system has been known for long. Supplementation with sodium butyrate exhibits a positive effect on the condition of the microbiota, which may indirectly translate into improved immunity [5].
- Improved life quality of people with IBS. IBS, or irritable bowel syndrome, is a condition whose etiology is not fully known. This disease is characterized by, among others abdominal pain, feeling of fullness, constipation/diarrhea (depending on the type of IBS), chronic inflammation, and abnormal bowel motility [6]. To put it simply: sodium butyrate regulates bowel function, which means that the compound may significantly reduce the symptoms associated with IBS [2].
- Functioning of the bowel-brain axis. Sodium butyrate can indirectly modulate the functioning of our central nervous system [7]. It is commonly known that intestinal microbiota strongly influences the peripheral functioning of the immune system, which ultimately may e.g. lead to the modulation of microglia cells. This is an important issue, as there are more and more reports indicating that microglia hyperactivity underlies neurodegenerative diseases such as Alzheimer's disease [8].
Not only healthy bowels
Sodium butyrate is most often talked about in the context of health care for the proper condition of the digestive system. However, it is believed that, apart from beneficial effects on intestinal microbiota, sodium butyrate is also a histone deacetylase (HDAC) inhibitor, which may indirectly exert anti-cancer effects [9]. Sodium butyrate alleviates excessive histone acetylation, which results in cell "arrest" in the G1 or G2/M phase [9]. This enables the activation of the expression of genes and proteins involved in cell differentiation and apoptosis [a]. In practice, this means that sodium butyrate may inhibit excessive and pathological cell division that is characteristic of cancer.
Why sodium butyrate?
Pure butyric acid is a compound with an extremely unpleasant odor, so administering it orally will not be the most pleasant experience. However, let's assume that this is not a disadvantage for someone (which is quite hard to imagine). Free, unbound, in the form of salt and devoid of a protective coat, the acid is quickly absorbed in the upper parts of the digestive system, which is not desirable because it is ultimately intended to reach our intestines [2]. Due to the above factors, butyric acid is best given in the form of sodium salt, which is covered by a mixture of triglycerides. Such modified butyric acid will enter our intestines in an unchanged form, and from there it will be gradually absorbed. Nevertheless, note that microencapsulated sodium butyrate is still not a compound with a pleasant odor. However, this is perfectly normal and acceptable.
Bibliography:
- Rechkemmer, G., Rönnau, K., & Engelhardt, W. (1988). Fermentation of polysaccharides and absorption of short-chain fatty acids in the mammalian hindgut. Comparative Biochemistry and Physiology Part A: Physiology, 90(4), 563–568.
- Załęski, A., Banaszkiewicz, A., & Walkowiak, J. (2013). Butyric acid in irritable bowel syndrome. Gastroenterology Review, 6, 350–353.
- Borycka-Kiciak, K., Banasiewicz, T., & Rydzewska, G. (2017). Butyric acid – a well-known molecule revisited. Gastroenterology Review, 2, 83–89.
- Segain, J.-P. (2000). Butyrate inhibits inflammatory responses through NFkappa B inhibition: implications for Crohn’s disease. Gut, 47(3), 397–403.
- Ratajczak, W., Rył, A., Mizerski, A., Walczakiewicz, K., Sipak, O., & Laszczyńska, M. (2019). Immunomodulatory potential of gut microbiome-derived short-chain fatty acids (SCFAs). Acta Biochimica Polonica.
- Padhy, S. K., Sahoo, S., Mahajan, S., & Sinha, S. K. (2015). Irritable bowel syndrome: Is it “irritable brain” or “irritable bowel”? Journal of Neurosciences in Rural Practice, 6(4), 568–577.
- Stilling, R. M., van de Wouw, M., Clarke, G., Stanton, C., Dinan, T. G., & Cryan, J. F. (2016). The neuropharmacology of butyrate: The bread and butter of the microbiota-gut-brain axis? Neurochemistry International, 99, 110–132.
- Navarro, V., Sanchez-Mejias, E., Jimenez, S., Muñoz-Castro, C., Sanchez-Varo, R., Davila, J. C., … Vitorica, J. (2018). Microglia in Alzheimer’s Disease: Activated, Dysfunctional or Degenerative. Frontiers in Aging Neuroscience, 10.
- Davie, J. R. (2003). Inhibition of Histone Deacetylase Activity by Butyrate. The Journal of Nutrition, 133(7), 2485S–2493S.