Why butyrate foods are essential to gut health
Butyrate is produced when gut bacteria break down fiber and other prebiotic foods—and it’s vital for a healthy gut and metabolism. Learn how to boost your levels with food.
By now, you’re familiar with probiotics—the “good” bacteria residing in your gastrointestinal tract that not only support gut health but, in turn, may help treat a slew of health issues, ranging from diabetes and obesity to autoimmune diseases and mental health conditions.
Maybe you’ve even heard of _pre_biotics, which serve as a food source for these good bacteria, allowing them to thrive. Butyrate, a byproduct of the body’s processing of prebiotics, is another lesser-known component of gut health. But what exactly does it do for your health, and how can you optimize your body’s levels with your diet? Below, we’ll explain.
What is butyrate?
Butyrate is a short-chain fatty acid (SCFA) produced when the bacteria in your gut (i.e., your large intestine or colon) break down prebiotics. These include soluble dietary fiber (found in legumes, fruits, and vegetables) and other non-digestible food components (like the resistant starch found in unripe bananas and cooked and cooled starchy foods like rice and potatoes).
While butyrate is one of several SCFAs produced by the breakdown or fermentation of prebiotics (others include propionate and acetate), it has an outsized impact on gut health because it’s the primary energy source for cells lining the large intestine (colonocyte cells), providing 70-80 percent of their energy needs.
Butyrate plays a crucial role in maintaining proper gut barrier function and gut microbial balance, and in activating anti-inflammatory signaling cascades. Because butyrate can pass into blood circulation, it may also have body-wide effects: Research suggests that butyrate may influence local and systemic inflammation, metabolism, blood sugar, and more.
What to know about _pre_biotics, butyrate, and gut health
Since butyrate is not provided directly by your diet but rather through the digestion of prebiotics, it’s helpful to know more about what prebiotics are and the foods they’re found in.
Prebiotics are non-digestible components of food that resist breakdown until they reach the colon. There are multiple categories of prebiotics, most of which are in carbohydrate-containing foods. These include fructans, galacto-oligosaccharides (GOS), trans-galacto-oligosaccharides (TOS), and starch and glucose-derived oligosaccharides. Common prebiotics you’d recognize from these categories are soluble fibers (e.g., inulin and pectin) and resistant starch.
Inulin is found in garlic, asparagus, and soybeans; pectin is in various fruits and vegetables, including apples, pears, and raspberries. Resistant starch is in foods like unripe green bananas and cooked-and-cooled lentils and rice.
Additionally, research suggests that some non-carb compounds, such as polyphenols (e.g., catechins in green tea and flavonols in cocoa), may function as prebiotics.
All prebiotic compounds resist digestion in the stomach and small intestines but are then metabolized and fermented by beneficial bacteria in the colon. As a result, two key things happen: 1) “good” gut bacteria multiply and thereby help crowd out populations of pathogenic and opportunistic bacteria, and 2) these “good” bacteria release fermentation byproducts like butyrate and other SCFAs (propionate and acetate) that regulate gut health and overall health.
Health benefits of butyrate in the gut and beyond
Butyrate is vital for gut health, which can impact your whole body. But making definitive claims about its benefits is tricky. While some exciting mechanisms have been identified in lab and animal studies, not all have been fully fleshed out in humans—or they’ve yielded mixed results.
Plus, some studies have examined the impact of supplemental butyrate, while others have looked at the relationship between prebiotic intake, subsequent butyrate production, and health outcomes—and these may have somewhat different impacts on health.
That said, the research on butyrate is quite promising, and suggests that many of us should be getting more fiber and resistant starch in our diets to aid butyrate production.
Gut barrier function and inflammation
The gut or intestinal barrier refers to the inner lining of the intestines. It consists of three main layers (from innermost to outermost): the mucus layer that comes into direct contact with digested food, a single layer of intestinal epithelial cells connected by tight junction proteins, and a layer of underlying connective tissue called the lamina propria. A healthy gut barrier is vital for proper immune system function and controlling inflammation, and butyrate strengthens the gut barrier by regulating tight junction proteins and supporting a healthy gut mucosal lining.
- Tight junction proteins (TJPs) are situated between intestinal epithelial cells and regulate the passage of substances between the gut and circulation. For example, when functioning correctly, TJPs allow for ions, solutes, and water to pass back and forth, while preventing harmful substances like toxins and undigested food particles from entering circulation. Thus, TJPs provide the gut with its “selectively permeable” properties. Supplemental butyrate has been shown in animal studies to upregulate tight junction proteins such as TJP1 and claudin 7.
- Butyrate also helps bolster the gut’s protective mucus layer. Specifically, butyrate has been shown in some (but not all) human and lab studies to upregulate the expression of genes such as MUC2 that instruct the body to produce mucin, a key component of mucus, which lines the gut. This mucus layer provides a protective buffer between the contents of the intestines and the cells lining the gut, thereby reducing the likelihood that antigens and bacteria will adhere to and infiltrate the gut lining.
Without enough butyrate, gut barrier integrity may suffer, and harmful substances (undigested food particles, digestive enzymes, and toxic and highly inflammatory microbial cell wall components called lipopolysaccharides) can infiltrate the gut lining and enter circulation, where they activate an immune response and subsequent inflammation. Animal studies have shown that resistant starch helps improve intestinal permeability and reduce systemic inflammation.
Inflammatory bowel disease
Butyrate also has direct anti-inflammatory effects on the gut: It inhibits the activation of NF-KB, a transcription factor (or a group of proteins) that turns on proinflammatory genes, and it helps create regulatory T cells, specialized immune cells that help control the production of pro-inflammatory cytokines and prevent autoimmunity.
Given these properties, butyrate may have a beneficial impact on inflammatory bowel diseases (IBDs), like Crohn’s disease and ulcerative colitis, that are characterized by an abnormal immune response, chronic intestinal inflammation, and a compromised gut barrier. IBDs are also associated with decreased butyrate production in the colon.
According to a 2023 research review, current literature suggests butyrate may be a valuable add-on therapy to reduce inflammation and support IBD remission. Per one small study of 13 people in the review, some patients with mild-moderate Crohn’s disease reported improved symptoms and decreased gut mucosal levels of NF-KB after taking 4 g of butyric acid per day for eight weeks. Butyrate-generating foods like germinated barley and oat bran have also been shown to increase fecal butyrate levels (an indicator of butyrate production in the colon) and reduce IBD disease activity.
Results are more mixed for irritable bowel syndrome (IBS), which doesn’t fall under the IBD umbrella. While one study found that butyrate capsules reduced pain, they did not alter the severity or frequency of other IBS symptoms. In fact, studies have shown that some IBS patients actually have elevated butyrate levels, and that butyrate may play a role in visceral hypersensitivity, the lower threshold for abdominal pain some people with IBS experience.
Just keep in mind: It’s possible that some butyrate-generating prebiotic foods could aggravate your IBD or IBS and other GI conditions. Many prebiotic foods are FODMAPs, which may increase symptoms. So, talk to your doctor or dietitian before making significant dietary shifts.
Colon cancer prevention
Butyrate may be one reason fiber-rich diets are associated with reduced colon cancer risk. Chronic inflammation in the colon increases colon cancer risk, and we already know that butyrate has powerful anti-inflammatory properties within the gut. Additionally, studies suggest butyrate can influence the activity of genes that affect cancer, inhibit cancer cell proliferation, and induce apoptosis or cancer cell death.
Many of these anti-cancer activities result from butyrate’s ability to inhibit a class of enzymes known as histone deacetylases (HDACs). But there are other potential mechanisms at play too: Lab studies suggest butyrate inhibits the glucose metabolism and DNA synthesis of colorectal cancer cells, which may slow their growth and enhance the effect of chemotherapy drugs. Butyrate also enhances motility, or movement of food through the GI tract, which is important, as constipation may play a role in the development of various GI cancers. Additionally, butyrate reduces carcinogen-induced DNA damage in lab studies through a variety of mechanisms.
While clinical research on humans has been a bit mixed, small studies suggest that butyrylated resistant starch intake increases fecal butyrate levels, increases butyrate-producing bacteria in the gut, and helps prevent the development of oncogenes (mutated genes with the potential to cause cancer), and cancer cell proliferation among people eating diets high in red meat.
Blood sugar balance
Butyrate may also support balanced blood glucose. A 2019 study found that increased gut production of butyrate was associated with an improved insulin response (i.e., insulin sensitivity) after an oral glucose tolerance test, and a recent not-yet-peer-reviewed clinical trial found that a supplemental prebiotic fiber mixture with resistant starch reduced HbA1C to a similar extent as oral diabetes drugs.
Butyrate’s impact on inflammation, immune cells, and gut hormones may play a role. As mentioned, butyrate supports the integrity of the gut barrier, and improved gut barrier function can reduce inflammation. This, in turn, promotes insulin sensitivity—meaning your cells are more responsive to insulin’s glucose-lowering effect. Research on animals also suggests that butyrate may help maintain proper functioning of insulin-producing pancreatic beta cells, partly through its action on immune cells such as regulatory T cells.
Both butyrate and its prebiotic precursor resistant starch have been shown in animal and lab studies to increase the secretion of the hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in the colon. GLP-1 increases insulin release, while PYY increases glucose uptake by muscle and fat tissue, which, together, can help keep blood sugar levels in check.
Weight management and obesity
Studies have shown that people with obesity and diabetes tend to have lower levels of butyrate-producing bacteria in their gut microbiome, suggesting low butyrate may contribute to these conditions. If that’s true, replenishing butyrate levels might help prevent or reverse these conditions—and at least some research appears to support this:
- Animal studies have shown that supplemental butyrate helps protect against diet-induced obesity and insulin resistance, which can drive fat storage. As previously mentioned, butyrate and resistant starch may also increase GLP-1 and PYY, which have appetite-suppressing effects; and studies on mice suggest that butyrate increases production of the “fullness” hormone leptin. Additionally, lab and animal studies indicate that butyrate intake may also increase fatty acid oxidation via several mechanisms.
On the other hand, research has also shown that people with overweight and obesity have higher levels of butyrate in their stool than lean people—which has led some researchers to believe it might contribute to obesity, but this has not been proven.
So what’s the consensus? According to a 2023 research review, ample evidence supports the idea that butyrate has beneficial effects on weight and obesity, but more comprehensive human clinical trials are needed to determine these specific effects.
Which foods are high in butyrate?
Prebiotic-rich foods are the best sources of butyrate. Most of the butyrate your body uses comes from the fermentation of prebiotics: resistant starches, soluble fibers, and polyphenols. Some research suggests that resistant starch results in greater butyrate production than some other prebiotic sources—but, overall, aim for a variety of these foods in your diet. Greater variety of plant foods in your diet contributes to greater microbial diversity, a marker of a healthy, resilient gut.
Small amounts of butyrate are found in full-fat dairy products and vegetable oil, but this butyrate is absorbed in the small intestines before it ever gets a chance to benefit the gut. (Plus, too much of these foods may contribute to excess saturated fat and omega-6 intake.)
Below are 39 prebiotic-rich foods to nourish your gut and boost the production of butyrate and other SCFAs. We’ve separated out resistant starches, which are found in fewer foods.
Resistant starches
- Unripe bananas
- Plantains (uncooked)
- Raw cashews
- Uncooked oats (e.g. overnight oats)
- Cooked and cooled potatoes
- Cooked and cooled sweet potatoes
- Cooked and cooled rice
- Cooked and cooled barley
- Cooked and cooled legumes
- Green banana flour
- Potato starch
Note: The resistant starch in potatoes, rice, barley, and legumes is only present in significant quantities if these foods are cooked and subsequently cooled. The good news: Reheating them doesn’t lessen their resistant starch content—so no need to eat cold unless you want to.
Other prebiotic foods
- Artichoke
- Asparagus
- Burdock root
- Chicory root
- Dandelion greens
- Jerusalem artichokes
- Seaweed
- Tomatoes
- Carrots
- Garlic
- Leeks
- Onions
- Mushrooms
- Beans
- Lentils
- Chickpeas
- Soybeans
- Chia seeds
- Flaxseeds
- Almonds
- Cashews
- Barley
- Apples
- Apricots
- Pears
- Raspberries
- Green tea
- Dark chocolate
How much should you eat?
There’s no official recommended daily intake of prebiotic-containing foods—plus, nutrition labels generally don’t distinguish between soluble and insoluble fiber, nor do they list resistant starch or total prebiotic content. A good strategy: Prioritize getting 35-50 grams of fiber per day from a variety of plant sources. Gradually work up to this amount to minimize gas and bloating.
Other ways to boost butyrate
Second to consuming prebiotic foods, taking a prebiotic supplement with minimal ingredients (think: no added sugars or sweeteners) may be your best bet for supporting natural SCFA production in the gut and reaping butyrate’s benefits. The bacterial fermentation of fiber, whether from food or supplements, results in a more prolonged period of butyrate production and absorption in the colon compared to supplemental butyrate (much of which is absorbed in the small intestine before ever reaching the colon). A variety of prebiotic supplements on the market contain prebiotic fibers such as inulin, acacia fiber, and guar gum, or a combination.
Acacia is a gentle fiber and may produce less gas than others on the market. “I love Acacia fiber for its soluble fiber making it a prebiotic, and its ability to help people feel full. It absorbs water helping it to expand and improve satiety,” says Levels advisor Dr. Molly Maloof, MD. Another gentle prebiotic fiber is partially hydrolyzed guar gum (PHGG), often sold as Sunfiber, which has been shown to reduce symptoms of diarrhea- and constipation-predominant IBS.
Butyric acid (or sodium butyrate) supplements, on the other hand, deliver more of a bolus of butyrate, which does not fully replicate natural butyrate production. These may benefit certain people, such as those with inflammatory bowel disease and other GI conditions, but be sure to talk to a healthcare provider knowledgeable about GI health and supplements before starting.
Finally, you can naturally boost butyrate production through exercise. A 2019 research review of animal and human studies found that exercise was associated with increased butyrate-producing bacteria and higher levels of butyrate in the stool—regardless of diet.
Learn how your body responds to your diet
The best way to understand what habits and foods help you achieve balanced blood sugar is with a continuous glucose monitor and an app like Levels to help you interpret the data. Levels members get access to the most advanced CGMs and personalized guidance to build healthy, sustainable habits. Click here to learn more about Levels.
