Eat fiber-rich foods to help your gut bacteria make short-chain fatty acids. Here’s what to eat and how much fiber you need for healthy digestion. We hear it from our doctors and commercials on TV: a healthy diet means eating more fiber. But why does fiber matter so much for us? Dietary fiber aids digestion by preventing and relieving issues like inflammation and constipation. Adding enough fiber to your diet also offers a lower risk of heart disease, diabetes, and obesity. But dietary fiber does much more than that. It feeds your forgotten organ.

Doctors sometimes refer to the healthy bacteria living in your gut as your “forgotten organ.” Maintaining the healthy bacteria is as important as keeping your intestines or colon healthy, and one of the ways you feed the bacteria is by adding fiber to your diet. Those bacteria love fiber, and while you can’t digest it, they ferment it to turn it into short-chain fatty acids.

Short-chain fatty acids contribute to a whole host of metabolic processes and getting enough of them helps those with digestive or gut disorders like Crohn’s or inflammatory bowel disease (IBD) as well as preventing cancer. What are short-chain fatty acids and where can you get more of them? Keep reading to find familiar sources of dietary fiber, fermentable fiber, and short-chain fatty acids.

What Are Short Chain Fatty Acids?

You won’t find short-chain fatty acids in foods but your gut. Rather than getting them directly from the food you eat, the healthy bacteria found in your colon take food and ferment it. The fermentation turns food into a vital energy source for the cells that line your colon. The fermentation process may change depending on the presence or absence of several factors. It may differ according to the number of microorganisms living in your gut, the time it takes to digest the food, and what food you eat.

Your gut often makes more than your colon needs, so short-chain fatty acids get used to fill in in other parts of your body. For example, your body uses them in metabolic processes that transform carbs or fat into energy. They also provide you with 10 percent of your daily calories.

The biology of short-chain fatty acids is simple: it’s any fatty acid with fewer than six carbon atoms. Almost all short-chain fatty acids fall into one of three categories:

  • Acetate
  • Butyrate
  • Propionate

Acetate has two carbon atoms; butyrate has four carbon atoms; propionate has three carbon atoms. The number of carbon atoms in a fatty acid may dictate its function. For example, acetate gets incorporated into long-chain fatty acids like cholesterol. Propionate serves a different purpose by helping the metabolic function that helps the liver produce glucose.

Food and Short-Chain Fatty Acids

ou don’t eat short-chain fatty acids, but the foods you eat help you make them. If you want to help short-chain fatty acids along, you’ll generally lean towards high-fiber foods like fruits, leafy green vegetables, whole grains, and legumes. Fiber is the essential building block for the fermentation process that creates short-chain fatty acids. Conventional sources of fiber serve the purpose, but nature doesn’t consider all fiber equally. There are several types of fiber, and some of them serve as better fuel for fermentation than others.

Different Types of Fiber Found in Food and What You Need for Short-Chain Fatty Acids

We often think of fiber as a single nutrient. In reality, it’s made up of different types of carbohydrates. What do those carbs have in common? The human digestive system can’t break them down. Although we know fiber as a critical component of digestion, we don’t have the enzymes to break them down ourselves. They pass through our systems mostly unchanged except for the fiber converted into short-chain fatty acids.

There are two formal types of fiber: dietary fiber and functional fiber. Dietary fiber is what you find naturally in foods like whole grains or dark, leafy vegetables. Functional fiber is a supplement that’s removed from whole foods and then mixed into processed foods. Separating fiber into dietary and functional categories don’t tell the whole story. We can also classify them as soluble or insoluble, viscous or non-viscous, or fermentable or non-fermentable. If you want to help your body produce short-chain fatty acids, your biggest concern is whether the fiber is fermentable or non-fermentable because fermentable fibers are critical for the fermentation process.

Fermentable and Non-Fermentable Fiber

If you want to feed the bacteria that ferment fiber into short-chain fatty acids, then you need foods rich in fermentable fiber. Your bacteria prefers this fiber because it feeds the bacteria and creates the acids.

Recognized fermentable fibers include:

  • Pectins
  • β-glucans 
  • Guar Gum
  • Oligofructose
  • Inulin

Meanwhile, fiber made from cellulose or lignin inhibit or resist fermentation.

How to Add Fermentable Fiber to Your Diet

Fermentable fiber comes from pectin, β-glucans, inulin, and oligofructose. These fermentable fibers aren’t as commonly found in our daily diets as we might like, but we don’t need a massive amount of fermentable fiber.

Here’s where to find good sources of each fermentable fiber type:

Pectin

β-glucans 

Inulins

Oligofructose

Guar Gum

How Short-Chain Fatty Acids Help Digestion

Why do we love short-chain fatty acids? In addition to contributing to metabolic processes, short-chain fatty acids help aid digestion in the midst of gut issues or disorders. For example, studies show that short-chain fatty acids help relieve diarrhea among children.

Short-chain fatty acids are found to be particularly helpful in stemming bowel inflammation. Chronic inflammation contributes to two types of disease: Ulcerative colitis and Crohn’s disease. Butyrate, in particular, is useful because it boasts anti-inflammatory properties. Studies also linked lower levels of short-chain fatty acids to an increase in symptoms in ulcerative colitis cases. Low short-chain fatty acid numbers also contribute to a higher risk of colorectal cancer.

Your Recommend Fiber Intake

You can get most of the fiber you need from food without needing a supplement. The American Heart Association says you need 25 to 30 grams of dietary fiber a day. They recommend getting the fiber from food rather than nutritional supplements, and doing it is easy. Add one serving of whole grain to every meal, swap out meat for legumes and beans a few days a week, and get your recommended daily fruits and vegetables.

Fiber is important, but studies show Americans still only get about 15 grams a day on average. That’s just about half of what you need for gut and heart health.

Be Wary of How Much Fiber You Add to Your Diet

On average, Americans get less fiber than they need. One of the reasons you should focus on improving your fiber intake through food rather than prebiotic, probiotic, and dietary supplements is because it’s hard to get too much fiber from food.

Short-chain fatty acids help soothe digestive disorders, but too much fiber itself may cause damage. A healthy diet usually provides enough fiber for all your metabolic functions including short-chain fatty acid production. While eating fiber-rich food is vital for good digestion, it’s important to remember that we can’t digest fiber. Eating more than we need for other processes adds excess fiber to our digestive system, and that comes with complications.

Ask your doctor before considering a fiber supplement. Scientists link fermentable isolated fiber in particular to gastrointestinal distress. Inulin, oligofructose, and guar gum all contribute to cramping, diarrhea, bloating, and gas. Manufacturers may use guar gum in weight-loss products, and those products may add to small bowel obstruction.

Eat More Fiber to Make More Short-Chain Fatty Acids

Short-chain fatty acids don’t exist in food. Instead, your healthy gut bacteria use fermentation to transform undigestable fiber into energy for your colon and all kinds of metabolic processes. Short-chain fatty acids help battle inflammation and promote gut health, but it’s important not to go overboard. Most of us don’t get the dietary fiber we need in the first place, and fresh food should be the first place you turn because getting too much fiber has the opposite effect.

How do you make sure you get enough fiber in your diet? Share your favorite fiber-rich foods in the comments below.

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