In the old days (like tens of thousands of years ago), humans had to eat a lot to get enough energy to survive. That’s because most of the food that didn’t run away or fight back — that is, plants — were very high in insoluble fiber and low in calories.
Think roots, stems, grasses — all the tough stuff necessary to obtain the precious macro- and micronutrients we need to live.
Humans can’t digest that fiber (meaning we can’t turn it into energy or building blocks for our bodies), so we did the next best thing. We partnered with critters who could and gave them a warm and safe place to live in exchange for some of that energy.
Those critters I speak of are the bacteria that live in our colons. They get their crack at our food after we’ve extracted everything we can as it moves through our digestive system. And microbiota digests that leftover fiber, turning it into, among other things, compounds known as short-chain fatty acids (SCFAs).
These SCFAs provide us with additional energy but do so much more. They can help prevent chronic disease, improve overall health, and keep our guts running smoothly. They can also fight inflammation and counter the development of cancers, neurological disorders, and metabolic diseases.
So, what are these amazing molecules? How do our gut bacteria make short-chain fatty acids? And what are the best sources of fiber to feed our gut microbiome?
What Are Short-Chain Fatty Acids?
SCFAs are a group of organic compounds produced through fermentation in your gut. There are specific bacteria in your intestinal tract — and particularly in your large intestine — that metabolize complex carbohydrates such as dietary fibers and resistant starch, turning them into SCFAs.
The gut colonocytes (cells that line the colon and play a central role in shaping the gut microbiota) have first access to the energy that comes from SCFAs. Your gut cells get about 70% of their energy from them. Gut cells’ favorite SCFA is butyric acid (also known as butyrate). After your gut gets first dibs, the remaining SCFAs are sent to your liver and then through circulation to your other tissues for energy. In total, SCFAs provide about 10% of your daily energy requirements.
Types of SCFAs
The three most common SCFAs produced by your gut microbes are acetic acid (also known as acetate), propionic acid (propionate), and butyric acid (butyrate).
Acetate
Acetate serves as an important energy source for host cells, particularly in the brain and peripheral tissues. It’s needed for your body to make cholesterol. It may also play a role in metabolic health, influencing insulin sensitivity and weight.
Propionate
This SCFA regulates the release of specific gut hormones related to appetite. It’s also critical in helping your body synthesize proteins from amino acids and make glucose from non-carbohydrate sources (which comes in handy if you’re fasting or engaging in intense exercise). Propionate is needed for your liver to turn any extra carbs into fat for long-term storage. While you might not appreciate this if you’re food secure, it’s a lifesaving strategy during times of frequent famine.
Butyrate
Butyrate can modify the expression of various genes, including those related to metabolism, inflammation, neurotransmitters, and maintenance of the gut barrier (the cells that keep undigested food particles from leaking into your bloodstream, where they can trigger all sorts of unwanted effects). It also affects how your body expends energy.
All three SCFAs possess anti-inflammatory effects, help uphold the integrity of the gut barrier, and may influence the gut-brain axis by boosting serotonin production in the colon. They influence the pH, nutrient uptake, and microbial balance in the gut environment.
And thanks to all this activity, they can provide a host of health benefits.
The Health Benefits of SCFAs
The more researchers study SCFAs, the more health benefits they discover. Some of the strongest recent evidence connects the compounds with gut health, brain health, immune function, and inflammation reduction, as well as the prevention of cancer and type 2 diabetes. SCFAs are also associated with a healthier body weight.
Short-Chain Fatty Acids and Gut Health
SCFAs are really important for the intestines. They provide energy to colon cells, regulate immune responses, and promote the integrity of the gut barrier.
On the other hand, when SCFAs are lacking, gut health is compromised. Without enough SCFAs, especially butyrate, there’s insufficient energy to carry out tissue repair processes within the gut, so tissues damaged by inflammation cannot heal. This can lead to abdominal pain and cramping, diarrhea (which may be accompanied by blood or mucus), and even rectal bleeding.
One form of inflammatory bowel disease (IBD), ulcerative colitis (UC), also appears to be worsened by reduced SCFA levels. A 2020 study found that UC patients had much lower concentrations of SCFAs compared with healthy subjects.
SCFAs are also closely linked to a type of IBD called Crohn’s disease (CD). Without the SCFAs maintaining a healthy gut barrier, controlling the immune response, and balancing the gut bacteria, intestinal inflammation can progress to the symptoms of CD: abdominal cramping, diarrhea, and unintentional weight loss due to the intestine’s inability to digest calories.
Short-Chain Fatty Acids and the Brain
Over the past couple of decades, researchers have discovered that the brain and the gut talk to each other — a lot. And that the health of one can significantly affect the health of the other.
A 2020 study found that mice given SCFA acetate supplementation had a reduced risk of developing Alzheimer’s disease. (Our view on the use of animals in medical research is here.) The researchers found that acetate treatment significantly improved the mice’s cognitive function and lowered neuroinflammation markers in their brains.
SCFAs also appear to have helpful effects against the development of amyotrophic lateral sclerosis (ALS), a serious neurodegenerative disease that affects the brain and spinal cord. By influencing communication between the gut and the brain and affecting hormone release, gut health, and immune responses, SCFAs may play a role in pathways related to ALS development.
We’re also discovering that SCFAs produced by gut microbiota play a significant role in influencing emotions and depression. An imbalance of SCFAs in the gut may lead to neuroinflammation, which in turn can affect mood and behavior, potentially contributing to depressive symptoms. Improving the quality of your gut microbiome may be one way to help address depression and improve your overall mood.
SCFAs and Immunity
As we’ve seen, low levels of SCFAs can lead to inflammatory bowel diseases. SCFAs can reduce inflammation in a couple of ways, both of which are related to your immune system.
SCFAs play a critical role in supporting the integrity of your intestinal barrier. This barrier can keep harmful molecules out of your bloodstream and, therefore, keep your immune system from overreacting. By interacting with immune cell receptors, SCFAs help regulate your immune response, promoting a balanced inflammatory environment.
SCFAs can also affect the gene expression of immune cells and suppress the overproduction of inflammatory molecules called cytokines.
What’s more, SCFAs can help with autoimmune diseases by regulating the immune system, reducing inflammation, and promoting the balance of immune cells. In autoimmune liver disease, for example, SCFAs may help maintain a healthy immune system and prevent excessive inflammation.
SCFAs Anticancer Benefits
Enhanced immunity brought about by SCFAs can suppress tumor growth and spread. In gastrointestinal cancers, the levels of SCFAs and the bacteria that produce them are often reduced, weakening the body’s ability to combat tumors. However, increasing SCFAs through dietary fiber, probiotics, or even fecal transplants (yes, it really is what it sounds like — taking a microbially healthy poop and putting it into the colon of someone whose microbiome is struggling) can help restore these levels, boosting the immune response and inhibiting tumor development.
SCFAs and butyrate, in particular, have been shown to help slow down the growth and spread of various types of cancer, including colorectal, lung, breast, and bladder cancers. They do this by affecting how cancer cells grow, send signals, and use energy. SCFAs may also increase the effectiveness of some types of chemotherapy, helping reduce the resistance some cancer cells have to these drugs.
SCFAs and Type 2 Diabetes
Since SCFAs play a role in regulating your body’s balance of glucose and energy, they can help prevent and manage type 2 diabetes. Supplemental acetate, propionate, and butyrate show promise as potential new treatments for type 2 diabetes by enhancing insulin sensitivity, controlling glucose levels, and boosting energy expenditure.
Of course, eating a diet rich in fiber can positively influence your gut microbiota to increase SCFA production, which might keep you from developing type 2 diabetes in the first place. Once insulin resistance is high, studies have shown that giving people supplemental SCFAs might be even more effective in reducing fasting insulin than dietary changes (not that it has to be one or the other!).
SCFAs and Weight Management
SCFAs can influence our hunger and eating behavior, too. A 2021 study found that people with lower levels of SCFAs in their feces had higher body mass index scores than those with higher levels, and had less “cognitive restraint” when it came to eating. (That’s a fancy way of saying that SCFAs made it easier for people to lose excess weight and stop eating when full.)
What Affects SCFA Production in the Body?
So if these SCFAs are so super important for health, what determines how much of them our bodies produce?
Diet Quality
The number one predictor of the SCFA levels in your body is your diet. You don’t have to copy our Paleolithic ancestors and eat tree bark and shrub roots; you can get plenty of fiber by eating unprocessed or lightly processed plant-based foods.
That’s not the default of the modern industrialized diet, though. Instead, it’s low in dietary fiber and consists largely of highly processed foods loaded with artificial ingredients and foods of animal origin (oil, sugar, meat, dairy, and eggs provide no fiber whatsoever). Such a diet leads to decreased production of SCFAs, which means there are fewer of them circulating in your body.
Feeding your gut bacteria enough fiber is critical for SCFA production, but it’s not the only thing that matters.
Antibiotics
Antibiotics can kill disease-causing bacteria, which can, in some cases, save lives. But they can also damage bacterial diversity in your gut. This can create a “vacuum” in your gut ecosystem that gets filled by bacteria that don’t produce SCFAs. Researchers have found a link between antibiotic use and subsequent decreases in the concentrations of SCFAs.
The imbalance in gut bacteria produced by antibiotics is known as “dysbiosis.” To add injury to injury, the bacteria that thrive in the absence of the SCFA-producing ones often cause inflammation throughout the body. As a result, this can compromise the power of your immune system to respond to threats.
Type 2 Diabetes
We’ve seen that SCFAs can improve insulin sensitivity, which can help people manage type 2 diabetes. But the process works in the other direction, too, whereby diabetes can lead to dysfunctions of gut bacteria that decrease SCFA production. People with diabetes tend to have lower levels of SCFAs, and people with lower levels of SCFAs are at increased risk of type 2 diabetes. This is what’s known as a “negative feedback loop.” But it can go the other way, too!
How to Increase Short-Chain Fatty Acids?
There are three main ways to increase SCFA levels in your body: diet, exercise, and supplementation.
Diet
You won’t find a lot of SCFAs in food, but that doesn’t mean diet doesn’t matter. Rather, as we’ve seen, the bacteria in your colon munch on the fiber you can’t digest and ferment it into SCFAs. So, the more fiber you get in your diet, the more SCFAs your microbes will make.
Mice fed a diet free of soluble fiber developed inflammation in their digestive systems and compromised intestinal health, which led to weight gain. It could be considered unethical to conduct such an experiment on humans, but most people eating modern industrialized diets do it to themselves anyway — which at least partly explains the epidemics of chronic inflammatory diseases and obesity that we see in developed countries.
How much fiber do you need to eat to have adequate SCFA stores? While our ancestors (who had pretty much the same physiology as we do) are estimated to have consumed up to 100 grams of fiber per day, current recommendations generally put the number between 25 and 40 grams of fiber daily.
Not all fiber is identical when it comes to conversion to SCFAs, however; some are better precursors than others. (Just like you have your favorite foods, so do your gut bacteria.)
The types of fiber that convert best to SCFAs are prebiotics like inulin and FOS (found in onions and garlic, artichokes, oats, wheat, chicory root, and bananas, among other foods); other prebiotics like GOS (highest in beans and some root vegetables) and fermented foods like kimchi and sauerkraut; and resistant starch (found in potatoes and sweet potatoes, legumes, and whole grains like barley, oats, and wheat). Mushrooms contain two types of fiber: chitin and beta-glucans, which also make your SCFA-producing gut bacteria very happy.
The six categories of foods that are high in fiber and, therefore SCFAs are:
Here’s an infographic to help you remember to include all these short-chain fatty acid food categories in your diet.
Exercise
Something about movement seems to trigger your gut bacteria to increase the production of SCFAs. Some studies report that higher levels of physical activity and cardiorespiratory fitness correlate with higher fecal concentrations of SCFAs (a non-invasive way to measure SCFAs in your body is to assay your poop). It appears that exercise stimulates a system in your body known as the gut-muscle axis, which basically means that your skeletal muscles and gut microbes talk to and affect each other.
Studies show SCFA levels increase after medium- and long-term exercise interventions.
So, in addition to feeding them right, taking your gut bacteria for regular workouts and walks can also increase their production of SCFAs.
Supplements
Supplements can increase short-chain fatty acids, with some directly providing SCFAs in the form of salts. Butyric acid salts, like sodium butyrate, calcium butyrate, potassium butyrate, and magnesium butyrate, are commonly used and have shown potential benefits in certain cases.
It’s important to note that while these supplements may temporarily enhance butyrate levels and associated benefits, they could also disrupt the balance and eventually lead to a decrease in overall SCFA levels.
Research indicates that there is insufficient evidence to support the effectiveness of SCFA supplements in promoting overall health, and it’s worth mentioning that these supplements are not FDA-approved.
On the other hand, another approach is to promote the growth of SCFA-producing bacteria in the gut by supplementing with certain forms of fiber. Prebiotic fibers like high-amylose maize starch and inulin are frequently utilized for this purpose. Other potential fiber supplements may use acacia or guar gum, methylcellulose, psyllium, or dextrin.
While fiber supplements can provide food for SCFA-producing bacteria, getting your fiber from whole plant-based foods offers additional benefits. Whole foods contain lots of other nutrients, including antioxidants, vitamins, and minerals, that are absent in fiber supplements. And some fiber supplements also include sugars, “natural flavors,” or other additives that you’re probably best off avoiding.
Recipes to Increase Your SCFAs
Get ready to supercharge your gut health with these three amazing recipes designed to enhance your short-chain fatty acid production! Packed with probiotics, prebiotics, and fiber, these dishes are perfect for creating a thriving microbiome that supports optimal health and wellness.
Dive into the delicious flavors and reap the benefits of a balanced, happy gut. Your taste buds and your gut bacteria will thank you!
1. 10-Minute Prep Banana Walnut Baked Oats
If you have organic rolled oats, nuts, seeds, and a variety of spices, you can create one of the simplest and most delicious breakfast recipes around. Just blend all the ingredients in a food processor, transfer to ramekins, and bake. The enticing aroma alone will wake up even the sleepiest family members! Plus, this baked oatmeal is teeming with fiber in the oats, nuts, and seeds. Not only do these oats help reduce inflammation, improve digestion, and support your immune system thanks to their ability to support SCFA production, but this recipe is also a delightful breakfast to start your day off right!
2. Probiotic-Rich Cucumber Salad
Indulge in the healthful benefits of our Probiotic-Rich Cucumber Salad. Crisp cucumbers, crunchy red cabbage, sweet carrots, and tangy kimchi all come together to nourish your gut with short-chain fatty acid-promoting ingredients. The naturally sweet and savory dressing adds a burst of flavor while providing antioxidants and more anti-inflammatory benefits. Garnished with sesame seeds, green onion, and cilantro, this salad is not just delicious but a powerhouse of ingredients to keep your gut bacteria happy and healthy!
3. Creamy Mushroom Soup With Chickpeas and Kale
Creamy Mushroom Soup With Chickpeas and Kale is a cozy and delicious bowl of plant-based goodness, perfect for nourishing your gut. Umami-rich mushrooms, onions, and garlic create a flavorful base and offer prebiotics to support gut health. Meanwhile, mineral-rich kale and protein-packed chickpeas add texture, flavor, and essential nutrients. The fiber in chickpeas and kale, along with chitin and beta-glucans from the mushrooms, promote the production of short-chain fatty acids in your gut. What’s more, all these ingredients come together to delight both your gut bacteria and your taste buds!
Don’t Underestimate the Benefits of SCFAs
Short-chain fatty acids provide significant benefits for gut health, brain function, immunity, blood sugar balance, and overall health.
A diet rich in plant-based fibers is essential for promoting SCFA production. Consuming whole grains, legumes, fruits, vegetables, nuts and seeds, and mushrooms can significantly enhance the levels of these beneficial compounds in the gut. Additionally, regular physical activity has been shown to increase SCFA production, further supporting overall health. By focusing on dietary and lifestyle choices that boost SCFA production, you can harness the power of these compounds to expand the quality and quantity of your life.
Tell us in the comments:
- How do you intend to nurture your short-chain fatty acid levels?
Featured Image: iStock.com/SurfUpVector
