Up to a 61% decrease in gut discomfort reported in ultramarathoners who followed a low-FODMAP diet before races
Ultramarathons are any footrace longer than a traditional 26.2-mile marathon. As these grueling events can last over 6 hours, runners exert themselves to the point of experiencing gastrointestinal distress like cramping, nausea and diarrhea.
This is concerning as gut discomfort is a leading cause of not finishing ultramarathons. 😣 Thankfully, new research shows following a low-FODMAP diet can significantly reduce gastrointestinal symptoms.
What are FODMAPs?
FODMAPs are types of carbohydrates that can be hard to digest:
- Fermentable – broken down by bacteria in the large intestine
- Oligosaccharides – fructans and galactans
- Disaccharides – lactose
- Monosaccharides – fructose
- Polyols – sugar alcohols like sorbitol
Common high-FODMAP foods include apples, milk, beans, wheat bread, and artificial sweeteners.
How FODMAPs Trigger Gut Discomfort
FODMAPs are osmotic, meaning they pull water into the intestinal tract. This extra fluid can cause bloating and distension. 💧
They also get fermented by gut bacteria, producing gas and stomach pain. 💨
During exercise, blood flow to the gut decreases, slowing digestion. This leaves undigested FODMAPs lingering in the intestines, exacerbating symptoms.
Research Findings on Low-FODMAP Diets and Ultramarathons
👩🔬 In a 2019 case study, an ultramarathoner with IBS followed a low-FODMAP diet leading up to and during a 6-day, 186-mile race [1].
Her gut symptoms decreased from severe (Visual Analog Scale score of 60-100 mm) during training to mild (VAS 30 mm) during the race. 📉
👨🔬 In a 2020 double-blind trial, 18 ultramarathoners followed either a high or low FODMAP diet for 24 hours before 2 hours of treadmill running [2].
- Low FODMAP diet: ✅ 61% less gut discomfort
- High FODMAP diet: ❌ More frequent and severe symptoms
👩⚕️ These studies show restricting FODMAPs before and during long endurance events like ultramarathons can significantly reduce runner’s gastrointestinal distress.
Tips for Following a Low-FODMAP Ultramarathon Diet 🥦
- 🌱 Eat more: Gluten-free grains, lactose-free dairy, eggs, meat, fish, leafy greens, carrots, citrus fruits
- 🚫 Avoid: Wheat, beans/lentils, milk, apples/pears, artificial sweeteners
- 🍞 Opt for low-FODMAP gluten-free breads and cereals
- 🥛 Choose lactose-free milk and yogurt
- 🥑 Limit high-fructose foods like mango, honey and agave
- 🧃 Use stevia or monk fruit sugar instead of sorbitol sweeteners
- 🍏 Bananas and blueberries are great low-FODMAP fruits
- 🏃♀️ For gut training, gradually increase FODMAP foods leading up to race day
The Bottom Line
Following a low-FODMAP diet can significantly reduce gastrointestinal distress during ultramarathon races lasting over 6 hours.
Restricting intake of poorly absorbed carbs like wheat, dairy and certain fruits may alleviate cramping, bloating and nausea.
Gradually reintroducing high-FODMAP foods through gut training could further improve gut health and performance.
Ultramarathoners should work with a dietitian to create a personalized low-FODMAP meal plan for optimal nutrition and racing success.
Behind the Research
🔬 Study Type: Systematic review of 7 clinical trials on low-FODMAP diets in ultramarathoners
🔗 Link to original research paper: Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms-A Systematic Review – PubMed (nih.gov)
👩🔬 Authors: Tansy Ryan, Ed Daly, Lisa Ryan, Atlantic Technological University, Galway, Ireland
References
[1] Gaskell, S.K. and Costa, R.J.S., 2019. Applying a low-FODMAP dietary intervention to a female ultraendurance runner with irritable bowel syndrome during a multistage ultramarathon. International journal of sport nutrition and exercise metabolism, 29(1), pp.61-67.
[2] Gaskell, S.K., Taylor, B., Muir, J. and Costa, R.J., 2020. Impact of 24-h high and low fermentable oligo-, di-, monosaccharide and polyol diets on markers of exercise-induced gastrointestinal syndrome in response to exertional heat stress. Applied Physiology, Nutrition, and Metabolism, 45(5), pp.569-580.
Ryan, T., Daly, E., & Ryan, L. (2023). Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms-A Systematic Review. Nutrients, 15(20), 4330. https://doi.org/10.3390/nu15204330
Study Summary
| Key Finding | Meaning |
|---|---|
| 61% less gut discomfort on low-FODMAP diet | Restricting poorly absorbed carbs alleviates symptoms |
| Low FODMAPS before and during race | Continue diet day of event for benefits |
| FODMAPs increase intestinal fluid and gas | Avoid foods that trigger these responses |
| Gut discomfort main reason for DNF | Managing GI distress improves ultramarathon finish rate |
