Short-chain fatty acids (aka SCFA's), are as their name suggests, fatty acids that contain 6 carbon atoms or less (hence "short-chain"). These fatty acids play a very important role in our gastrointestinal health.
SCFA's are produced as a byproduct of the fermentation process by various bacterial strains that live within our gut microbiome. They provide the cells of the colon (our colonocytes) with an important source of energy, PLUS a wide range of other benefits (which we'll dig into shortly).
There are three main SCFA's that we're going to cover here:
Butyrate
Acetate
Propionate
What are the health benefits of SCFA's?
Butyrate
Butyrate is the SCFA that is a major energy source for the cells that line the colon. It's really important for the health of the mucosal lining in the colon (helping to bring down inflammation levels in the mucosa, butyrate could be helpful in cases of IBD), and has also been shown to reduce colorectal cancer risk.
It's also been shown to strengthen intestinal barrier function (protecting the mucosal lining from potentially harmful pathogens), play a role in lowering oxidative stress, improving intestinal motility, and regulating immunity.
The main producers of this specific SCFA in the gut seem to be Faecalibacterium prausnitzii, and Eubacterium rectale/Roseburia spp. You cannot take these strains in a probiotici so supporting these bugs through nutrition and lifestyle is important!
Acetate
Acetate is the most abundant SCFA produced by bacteria in the colon. This specific SCFA plays an important role in maintaining homeostasis (or "balance") within the gut microbiome. It may also play a role in appetite regulation and satiety.
Members of the Bifidobacterium and Lactobacillus species are known to produce acetate, as well as strains like Akkermansia muciniphila.
Propionate
This SCFA has been shown to reduce serum cholesterol levels, plays a role in gluconeogenesis in the liver (it's a precursor to this process, where the liver produces glucose in the case of low availability of serum glucose), and may have anti-cancer properties, similar to butyrate.
Produces of propionate in the gut are mainly gram-negative members of the Bacteroidetes phyla.
How do we support the production of SCFA's?
So now that you've learned about what SCFA's are, and how they can benefit your health, you may have the question: well how do I make sure my microbiota can make enough of them?
Great question!
Here are some ways you can support the production of SCFA's:
Certain types of indigestible fibers (like galacto-oligosaccharides, and inulin) are fermented by certain species to create acetate. You can get more of these types of fibers by eating (xyz): chicory root, onion, banana, garlic, leek, legumes, cashews, blueberry, pear, pistachio
Resistance starch and dietary fibers (like prebiotic fibers), are fermented by bacteria in the microbiome to make these SCFA's. Here are some that you can incorporated on a daily basis: onion, garlic, cooked and cooled potatoes, berries, apples, oats, chicory root, leeks, shallots, cooked and cooled rice, plantain flour, green banana
The species Akkermansia muciniphila can be supported via consuming fructo-oligosaccharides, polyphenols, and potentially polyunsaturated fats found in fish oil (and/or well-sourced oily fish).
The species Faecalibacterium prausnitzii can be supported via consuming polyphenols, inulin-type fructans and arabinoxylans. Incorporate these foods on a daily basis: chicory roots, onion, banana, garlic, leek, rice, barley, oat, sorghum, kiwi
Supplementing with SCFA's
In certain cases, it could be beneficial to lean on supplemental SCFA's — especially when commensal bacteria levels are very low (this could be discovered through a GI-MAP stool test which all of my clients get access to).
When commensal bacterial levels are low, and there may not be enough to produce SCFA's. This can lead to inflammation in the gut, a compromised intestinal lining, and a lack of energy for the colonocytes to use. Therefore, in cases of inflammatory conditions of the bowel, and intestinal permeability, this can be really helpful in the interim while you support your commensal flora, too!
As always, I recommend chatting with your practitioner to see if this is something that could benefit you.
If you're struggling with digestive issues, and you'd like to look deeper into your gut microbiome to see what might be responsible (including whether or not it might be low commensal bacteria and SCFA's like mentioned above), then definitely check out my Gut Reset Program and Gut Rehab Intensive where we can look into this via functional testing.