Key Takeaways
Fiber does more than support digestion—it feeds beneficial gut bacteria that help maintain the gut barrier, immune, and overall health.
Not all fiber works the same—prebiotic soluble fibers support your microbiome, while insoluble fiber promotes digestive regularity.
Eating a variety of fiber-rich whole foods helps support a diverse, healthy microbiome and overall digestive wellness.
Dietary fiber is a special group of non-digestible carbohydrates and plant structures that can be further broken down into soluble and insoluble fibers. These play important roles in digestion, gut microbiome health, gut barrier integrity, immune health, and other aspects of wellness.1 The Institute of Medicine (IOM) and USDA recommend 14 grams of fiber per 1,000 calories consumed daily.2 However, research shows that roughly 95% of Americans don't get enough fiber each day.3 Why? The “Western diet” often consists of ultra-processed foods that are low in fiber. Additionally, low-carb and gluten-free diets can unintentionally reduce fiber intake by excluding whole grains.4,5
When we talk about fiber and gut health, we're mainly referring to soluble fiber.
This type includes pectins, inulin, oat- or barley-derived beta-glucans, FOS, GOS, and other fibers that dissolve to form a viscous gel in the gut.1 Our bodies lack the digestive enzymes to process these fibers, so healthy gut bacteria in our gut step in. They feed on these “prebiotic” fibers, fermenting them to produce short-chain fatty acids (SCFAs) and other biologically relevant molecules.
There are many strains of helpful bacteria, and each prefers particular kinds of fiber and may create different SCFAs from them. These SCFAs serve various purposes in supporting digestive health. (For example, butyrate supports the health of cells in the digestive tract. This helps support gut barrier function.6 Propionate and acetate play roles in supporting healthy appetite and immune function.7,8)
If you're looking to incorporate more fiber foods for gut health, aim for a mix from these categories:
Foods in this category are among the most nutrient-dense sources of combined dietary fiber.9 Examples include lentils, chickpeas, beans, and dry peas.
Unlike refined grains, whole grains retain the bran and germ layers, which contain most of their fiber and micronutrients.10 Good sources include barley, quinoa, oats, brown rice, and even popcorn (air-popped for the healthiest option—try it with nutritional yeast).
In addition to packing micronutrients, fruits and vegetables are great sources of fiber. Artichokes, green peas, collard greens, Brussels sprouts, and broccoli are all high in fiber. While asparagus, garlic, leeks, and onions don't have the highest total fiber content, they are rich in prebiotic fibers like inulin and FOS.11
As a general rule of thumb, if there is an edible skin (e.g., sweet potatoes), leave it on. That goes for fruit, too. Apples and pear skins hold a large percentage of their fiber. Passion fruit, avocado, guava, raspberries, and blackberries are also high-fiber fruits.
When assessing the fiber content of foods, look at the ratio of total carbohydrates to dietary fiber. Aim for 1 gram of fiber per 5 grams of carbohydrates, with a 1:10 ratio being the upper limit of a good range.12
In general, a healthy microbiome is made up of a diverse community of helpful bacterial strains. To support microbial diversity, include a wide variety of fiber-rich whole foods in your diet, rather than relying on a few favorites. A common rule of thumb is to eat at least 30 different plant species per week.13
Look for places in your diet where you can substitute refined-flour products and processed snacks with high-fiber foods for gut health. Look beyond marketing phrases like “multigrain” and “12 grain” and check the ingredient label for “whole grain.” Replace between-meal snacks with raw nuts, seeds, or fresh berries.
While diverse whole foods are the essential foundation for getting your recommended daily fiber and nutrients, it's not always easy to consistently hit those targets. In these cases, can be a convenient way to help common nutrition gaps. More specifically, psyllium husk supplements are a popular choice for those seeking fiber for digestive health, while is specifically studied for its prebiotic, bacteria-feeding effects.
AG1 Essentials Gummies deliver 5 grams of dietary fiber (inulin + tapioca). Additionally, they include 50 whole-food-sourced ingredients for daily nutritional support in a convenient, great-tasting gummy. AG1 Essentials Gummies are also NSF Certified for Sport®, meaning they've been rigorously third-party tested for label accuracy and 280+ banned substances. Try it today.
Both nuts and seeds pack tons of fiber, though seeds are generally higher. Chia and flax are powerhouses, while pumpkin, sesame, and sunflower seeds also deliver. For nuts, almonds, pistachios, and pecans are a good bet.