The 15 best prebiotic foods for gut health
The importance of maintaining a healthy gut microbiome has been gaining more attention.
The gut microbiome contains trillions of microorganisms, most of which are bacteria, and plays a major role in various aspects of our health.
Probiotics and fiber have gotten a lot of fanfare lately when it comes to gut health, but in order to feed the “good bugs” or beneficial bacteria in our intestines, we also need to eat adequate prebiotics.
Unlike probiotics, prebiotics are not live microorganisms, and although most prebiotics are different types of fiber, not all prebiotics are fiber. So what are they?
Prebiotics are defined as substrates that are selectively used by the gut microbiota that produce a health benefit for the host (i.e. us humans). Substrates are molecules that enzymes act upon and can include indigestible fiber, polyphenols and polyunsaturated fatty acids. So in essence prebiotics serve as food for beneficial microbes in our guts that result in the production of beneficial metabolites like short chain fatty acids that have anti inflammatory and anticancer properties for humans among other health benefits.
According to UK researcher Glenn R. Gibson who introduced the term prebiotics to the scientific world, “Prebiotics are safe, efficacious, and user friendly. They can also be used prophylactically [and] as an adjunct to existing therapy.”
Some of the health benefits of regularly consuming prebiotics include:
Improved immune health and reduced inflammation
Reduction in diarrhea and constipation
Reduced risk of allergies
Improved mineral absorption
Improved metabolic health (insulin resistance, blood lipid levels)
Protective effects against cardiovascular disease and colon cancer as well as irritable bowel syndrome (IBS) and Crohn’s disease.
A low consumption of prebiotics may be detrimental to human gut health resulting in a lower production of short chain fatty acids, increased intestinal permeability and increased pathogen infection. In fact, a low FODMAP diet that’s often recommended as a treatment for IBS and is low in fermentable fibers such as prebiotics is not recommended long-term as it has been shown to cause a reduction in beneficial bacteria.
Common prebiotic fibers include: inulin, human milk oligosaccharides found naturally in breast milk, galato-oligosaccharides (GOS), and fructo-olgiosaccharides (FOS). Luckily prebiotics are found in a variety of foods.
15 best prebiotics
Vegetables
Onions are rich in the polyphenol quercetin, contain about 10% inulin fiber by weight and also contain the prebiotics fructan and FOS which have been shown to increase the amounts of beneficial bacteria and the short chain fatty acid butyrate production in the intestines.
Leeks belong to the Allium family like onions, and contain up to 16% inulin fiber by weight. They’re also high in the antioxidant kaempferol which has anti-cancer, anti inflammatory and antimicrobial properties. They’re also rich in vitamins B6, C and K as well as folate and manganese and of course maintain a healthy gut.
Garlic is a tasty condiment that has antimicrobial effects and is one of the best prebiotics. It contains inulin and FOS and has been found to stimulate the growth of beneficial Bifidobacteria and may reduce gastrointestinal disease. Eating raw garlic has more health benefits for your immune and digestive systems.
Jerusalem artichokes: Although their name is deceiving, this tuber vegetable is actually related to sunflowers and not globe artichokes. They’re high in inulin which feeds beneficial bacteria and can be eaten cooked or raw.
Chicory root is one of the richest sources of the prebiotic inulin and is often used as a caffeine free coffee replacement. Chicory can decrease constipation, increase beneficial bifidobacteria and improve gut function. It contains almost 65% of fiber by weight making it one of the best prebiotics you can consume.
Asparagus is rich in antioxidants and fiber, especially inulin. The polysaccharides found in asparagus may be protective against liver cancer. It’s prebiotic benefits are more potent when eaten raw.
Fruits
7. Bananas are rich in carbohydrates, vitamins and minerals. Consuming bananas has been shown to increase beneficial bifidobacteria in the gut. Eating unripe green bananas may confer even more benefits as they contain high amounts of resistant starch, which exerts prebiotic effects, and may also reduce insulin resistance.
8. Apples are high in antioxidants, vitamins A, C, E, folate, and potassium as well as the fiber pectin. The fiber in apples along with their phenol content, which have prebiotic effects on the gut, can improve digestion and lipid metabolism. For the most nutritional benefit, be sure to eat the peel where the antioxidant content is the highest. Compared to conventionally grown apples, organic apples have been found to harbor less pathogenic bacteria and more beneficial bacteria like Lactobacilli offering additional probiotics. So skip the apple juice and eat the whole fruit for the best prebiotic benefits.
Legumes and Grains
9. Chickpeas, like other legumes like lentils and beans, contain various types of prebiotic fibers including FOS, GOS and fructans and are a rich source of vitamins and minerals. GOS consumption can lead to increased Bifidobacteria levels in the gut, whereas fructans have been shown to increase lactic acid bacteria. To enjoy their prebiotic benefits, chickpeas can be eaten boiled, canned or as used as a flour in baked goods.
10. Wheat bran is the hard outer layer of the wheat kernel and is high in not only fiber but also starch, protein, vitamins, and minerals. It’s a major source of cereal fiber intake in Western countries and one of the best prebiotics because it contains arabinoxylan-oligosaccharides which exerts a pronounced prebiotic effect that can improve stools and transit, lead to a healthy gut environment, and increases the amount of beneficial bacteria as well as short chain fatty acid production in the gut.
11. Oats contain one of the best prebiotics studied called beta-glucan. Of all the types of oats, oat bran has the highest fiber and beta-glucan content. The prebiotics in oats have been shown to increase beneficial Bifidobacteria species in the gut which can also reduce plasma cholesterol concentrations. Consuming oatmeal porridge has also been shown to improve the gut microbiota composition. The beta-glucan found in oats also have anticancer properties and may improve blood sugar.
12. Barley, like oats and wheat, contain the prebiotic beta-glucan and can also lower blood sugar. Studies have shown that barley can increase short chain fatty acid production in the gut and can significantly change the gut microbiota composition, such as increasing Lactobacillus strains in the gut. Beta-glucans found in barley have also been shown to reduce total and LDL cholesterol.
Seeds
13. Flaxseeds are rich in fiber, the omega 3 fatty acid alpha linoleic acid (ALA), lignans and antioxidants that promote regular bowel movements and regulate blood sugar. One study showed that the gut microbiota fermented the flaxseed fiber into short chain fatty acids which were protective against obesity. Due to its high omega 3 content, it’s best to eat flaxseeds raw so that cooking doesn’t oxidize the fatty acids. Lignans may prevent certain cancers, especially hormone related cancers they’ve been found to regulate estrogen levels.
14. Walnuts are packed with vitamins, minerals, antioxidants and essential fatty acids including ALA, antioxidants. Consuming walnuts regularly (43g/day, or about 3oz) has been shown to enhance probiotic and butyric acid-producing species in the gut. In addition to its fiber content, the prebiotic effect may come from the main polyphenols in walnuts, ellagitannins. Besides positively affecting the gut microbiota composition, walnuts can also reduce LDL cholesterol.
Other
15. Polyphenols are plant components necessary for the plant’s survival that benefit our overall health and recently have been found to have prebiotic effects on the gut microbiota. Common polyphenols are often found in so-called “superfoods” that include flavonoids, tannins, curcumins, and resveratrol. The foods that contain high levels of polyphenols that act as some of the best prebiotics include dark chocolate, caffeinated and decaffeinated green tea, red wine, and berries.
For example, consuming cacao flavonols has been shown to increase beneficial bifidobacteria and Lactobacilli in the gut. Other benefits polyphenols exert include decreasing inflammation and pathogenic bacteria and increasing short chain fatty acid production in the gut. They also have antimicrobial properties in the gut and may also improve cardiovascular health.
Conclusion
Despite the positive impact fiber consumption has on the gut microbiome and digestive health, most people in Western countries do not consume the recommended 25-30 grams of fiber per day. Additionally, low carb diets have become popular which may have detrimental effects on the gut since they tend to be low in the best prebiotics.
Current studies suggest that consuming between 2.5-10g of prebiotics a day is needed to experience their health benefits. On the other hand, consuming high doses (40-50g/ day) may cause gas and diarrhea.
Although many processed foods now contain prebiotics ranging from yogurt to infant formula, focusing on including these best prebiotics is an easy and effective way to support your overall gut and physical health.
***This article was originally written for Happiness.com
