Fueling your Gut with Carbohydrates and Prebiotic Fiber: An Update on the Science for Competitive Athletes and Weekend Warriors

10 min read

Fueling your Gut with Carbohydrates and Prebiotic Fiber: An Update on the Science for Competitive Athletes and Weekend Warriors

Carbohydrates And Sports

Carbohydrates, along with protein and fat, are major macronutrients required in the diet daily. For an average person on a 2,000 calorie per day diet, it is recommended to consume between 45-65% of those calories from nutrient-dense carbohydrate foods.1 For active adults and competitive athletes, carbohydrate recommendations are even more personalized and would consider a person’s body weight, type and duration of exercise training, intensity, or participation in team sport.

For example, certain athletes who participate in team sports may require between 500-800 grams of carbohydrate per day to help fuel and prepare for competition (for context, 1 slice of whole wheat bread provides about 15 grams of carbohydrate); so yes that’s a lot of carbohydrate! Including high amounts of carbohydrate in the diet, helps promote carbohydrate availability for working muscles and ensures that fuel targets are met for performance.2

Nondigestible Carbohydrates And Sports

Due to the demand for carbohydrates in the active population and the role that they play in providing energy for the brain, central nervous system and working muscles, carbohydrates have received considerable attention in the sports nutrition world.2 Nondigestible carbohydrates including prebiotic fibers and resistant starches are also of interest, due to their ability to help support microbial diversity in the gut, and to support overall gut health.3 While the science in the athletic population is still evolving, a study in endurance trained athletes found that supplementation with a prebiotic resistant starch for 28 days increased favorable microbial species including Parabacteriodes distasonis and Faecalibacterium prausnitzi. The promotion of these types of microbial species are important because low diversity has been associated with compromised gut health.4

Exercise Performance And The Gut

Furthermore, the connection between dietary intake, exercise performance and the gut has been explored.5 6 7 The gut is a very active organ and regular exercise and training plays a beneficial role by affecting the structure and diversity of the gut microbiota.5 For example, research in athletes have reported higher gut microbiota diversity, along with a higher relative abundance of butyrate-producing bacteria compared to sedentary individuals.7 8

Butyrate, as one of the major short-chain fatty acids (SCFAs) produced in the colon, can be used as fuel by colonocytes. In terms of exercise performance, SCFAs can be incorporated into glucose or increase the availability of it during exercise.3 SCFAs produced from the fermentation of prebiotic fiber has also been positively associated with muscle function.3 For these reasons, athletes who are interested in optimizing performance, should consider incorporating prebiotics as a nutrition and fueling strategy to promote a healthy gut microbiome.

Prebiotics are non-digestible carbohydrates that can pass through the digestive system, until they hit the colon where they are fermented by naturally present bacteria to produce metabolic by-products (SCFAs), including acetate, propionate, and butyrate. A number of foods and beverages contain prebiotic fibers including oats, chickpeas, asparagus, leeks, chicory, garlic, artichoke, onion and functional prebiotic fiber containing beverages such as OLIPOP.

Exercise, Fiber and Gut Health

While prebiotic fiber is important and has many benefits for gut health, some athletes may follow a low-fiber plan prior to exercise, training or a major event or competition. This is because ingestion of too much fiber close to a workout may cause gastrointestinal disturbances. Endurance athletes particularly experience GI disturbances9, due to reduced blood flow to the gastrointestinal tract over time, resulting in the depletion of energy (ATP), stress, and low oxygen levels. In response to this, the gastrointestinal tract releases signals that are associated with gastrointestinal disturbances. This is particularly the case when adequate nutrition and rest are not followed post-workout.3 However, this is not the case for all athletes; especially if habitual fiber intake is well tolerated and adequate during training and days leading up to a major competition or event. While research in this area continues, active individuals and athletes should consider that their gut is an active organ that needs to be properly nourished with nutrient-dense carbohydrate choices for beneficial effects on performance. Prebiotics can help alter the gut microbiota, with potential benefits for athletic performance.3

Optimizing Performance and Training Your Gut

Here are some practical takeaways for athletes and weekend warriors to help optimize performance and train your gut:

  • Think about including nutrient-dense carbohydrates, including prebiotics, in your diet such as whole grains, a variety of fruits, veggies, and starches
  • Consider working with a registered dietitian (RD) to help design an eating plan that fuels optimal performance during the pre-exercise, during exercise and post-exercise recovery period
  • Troubled by GI disturbances on occasion? Modify your diet during training and work with a dietitian to help customize a plan that minimizes disturbances and symptoms of it during competition day
  • Are you a low-fiber consumer to begin with? Consider introducing one fibrous food or beverage at a time to give your gut time to acclimate to these new foods or beverages
  • Understand that each athlete and person have a unique GI tract and finding a nutrition regimen that works best may take adaptation and time


  1. Institute of Medicine: Dietary Reference Intakes. Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, DC: National Academy Press; 2002.
  2. Thomas D.T., Erdman K.A., and Burke L.M. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance J Acad Nutr Diet 2016; 116(3): 501-528.
  3. Hughes R.L., Holscher H.D. Fueling Gut Microbes: A Review of the Interaction between Diet, Exercise and the Gut Microbiota in Athletes Adv Nutr 2021; 12: 2190-2215.
  4. West N.P. et al. Butyrylated starch increases colonic butyrate concentration but has limited effects for immunity in healthy physically active individuals. Exercise Immunol. Rev 2013; 19: 102-119.
  5. Jang L.G., Geunhoon C, Sung-Woo K, Byung-Yong K, Sunghee L, Park H. The combination of sport and sport-specific diet is associated with characteristics of gut microbiota: an observational study Journal of the International Society of Sports Nutrition 2019; 16:21.
  6. Rios J.L., Bomhof M.R., Reimer R.A., Hart D.A., Collins K.H., Herzog W.H. Protective effect of prebiotic and exercise intervention on knee health in a rat model of diet-induced obesity Nature 2019; 9:3893.
  7. Estaki M, et al. Cardiorespiratory fitness as a predictor of intestinal microbial diversity and distinct metagenomic functions Microbiome 2016; 4(1): 42.
  8. Barton W, et al. The microbiome of professional athletes differs from that of more sedentary subjects in composition and particularly at the functional metabolic level Gut 2018; 67 (4): 625-33.
  9. de Oliveira EP, Burini RD, Jeukendrup A. GI complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Med 2014; 44(81): 79-85.
Cheat Sheet
  • Consider including nutrient-dense carbohydrates in your diet such as whole grains, a variety of fruits, veggies, and starches
  • Talk to a registered dietitian (RD) to help design an eating plan that fuels optimal performance
  • Try introducing one fibrous food or beverage at a time to give your gut time to acclimate to new foods or beverages

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