You may be wondering why so many of our articles are, at this point in time, focussed on gut health. Well that is simply due to how important the digestive system is to many other systems in the body. It is also the system that we see the most frequent imbalances in. This article discusses short chain fatty acids, one of the reasons why nutritionists keep going on about fibre!
What Are Short Chain Fatty Acids?
They are the main bacterial metabolites produced following the fermentation of dietary fiber and resistant starches by specific colonic anaerobic bacteria.
The predominant SCFAs produced by bacterial fermentation in the colon are acetate, propionate and butyrate.
Insoluble fibers are highly fermentable and hence generate greater quantities of SCFA in the colon while soluble fibers have a rather low fermentability but increase fecal bulking and decrease colonic transit time.
Resistant starch is considered as the most powerful butyrogenic substrate
For food sources of resistant starch read our article here. Short chain fatty acids directly influence the large intestine environment, for example, by lowering intestinal pH, which inhibits the growth of pathogenic bacteria, increases the absorptive potential of minerals, and inhibits absorption of compounds with toxic or carcinogenic potential. Short chain fatty acids also stimulate colonic blood flow, increase tone and nutrient flow, promote colonocyte proliferation, and reverse atrophy associated with lowfiber diets.
Other benefits include:
These data aligns with a “diet hypothesis” which suggests that adequate intake of fiber promotes a healthy microbiota that significantly reduces the prevalence of inflammatory diseases, notably through the release of SCFA
the antimicrobial activities of individual SCFAs were relatively inert toward species of bacteria that produced them but were otherwise potent toward other microorganisms. Therefore, the production of SCFAs themselves may play a significant role in the shaping of the gut microbial ecology
Anti-leaky gut (so to speak)
Gut integrity is an essential factor in maintaining mucosal homeostasis. It is ensured by an efficient separation between the gut luminal contents and the host, which is partly due to an effective epithelial barrier. Disruption of gut integrity has been attributed to various intestinal diseases such as inflammatory bowel disease, celiac diseases, irritable bowel syndrome. A layer of mucus forms a physical barrier that separates the epithelium from the luminal environment, and this contributes to gut integrity by limiting physical access of bacteria to the epithelium, thus limiting prospects for breach and inflammation
Support a healthy gut microbiome
Apart from acting on the epithelial layer, SCFAs might promote gut integrity by maintaining symbiosis. Indeed, by lowering the luminal pH, SCFAs can directly promote the growth of symbionts, and on the other hand inhibit growth of pathobionts
Supports metabolic health
It is well established that supplementing resistant starch and dietary fibers in diet, which raises intestinal and circulating SCFAs, confers metabolic benefits in humans
Do Short Chain Fatty Acids Support Brain Health?
Pharmacologically, butyrate has had a profoundly beneficial effecton brain disorders ranging from neurodegenerative diseases to psychological disorders…Indeed,there are many reports of high fiber diets increasing blood levels of circulating butyrate. These later reports raise the possibility that increases n circulating butyrate could affect CNS functiondirectly.
The above image summarises the various proposed mechanismsin which butyrate may influence brain health in a number of different neurological disorders. Pharmacologically, butyrate is capable of targeting many pathways with multiple mechanisms of action that are disease specific. The dietary sources of butyrate througha high fiber diet or a diet rich in natural sources of butyrate is a highly appealing approach, as it presents a simple and relatively low risk method to potentially improve outcomes in patients with brain disorders.
As the current literature suggests, we can no longer overlook the importance of the gut-brain axis and nutrition in disease pathogenesis and treatment.
Increasing Fibre To Increase Short Chain Fatty Acid Levels
For some general guidelines around supporting digestive health, and sources of different types of fibre, see our article here.
Short Chain Fatty Acid – Conclusion
At Conquering Fatigue Solutions we frequently see low levels of key bacteria, such as lactobacillus, and low levels of butyrate. Ensuring adequate fibre intake is a key dietary intervention to support a healthy gut and thus healthy body. This needs to be put in to context alongside the health of the individual as certain fibres may exacerbate symptoms such as constipation. As always recommendations need to be personalised the best they can, and even then there is a degree of trial and error. We can’t always be 100% sure how the body will react to an intervention.