The ULTRA: Gut Impact.

The ULTRA: Gut Impact.

So now you have a combined situation of reduced blood supply to the gut, and heat build-up in the gut – leading to a direct threat to the integrity of the gut lining.

But the threats and damage from an endurance sports lifestyle don’t stop there.

Simple Sugar/Fructose adding further, Gut inflammation

We have already published articles that summarize the concern over intense simple-sugar ingestion by endurance athletes, and the potential health risks this places on the athlete and the longevity of their lifestyle-sport.  But let’s come back to the Gut, and focus on the sugar (sucrose) and fructose impact to the gut alone.

In a recent study, documented in the Journal of Nutrition and Diabetes, it was shown that excess free fructose consumption, creates a fructose-reactive state in the gut resulting in the formation of advanced glycation end-products (pro-inflammatory mediators) in the gut.  Furthermore medical studies, even from over 10 years ago, began showing that 3 in 4 tested people have a fructose-intolerance triggering digestive disturbances like pain, bloating, flatulence, and diarrhea.

Foods high in fructose?  Dates, syrups, cereals, energy-bars, dried-fruits, Colas, ‘sports-drinks’.  If you’re an endurance athlete you’ll know all these foods have been consistently included in packaged endurance foods for the past 30 years.  



We then see the food industry attempting to bypass this by adding artificial sweeteners to foods – including endurance food energy foods. But this only further complicated the problem, as these too are well published in terms of their impact on gastro disturbances like gas, bloating and flatulence.

And now to add insult to injury, we see careless sports food products, mixing refined sugar carbs with ‘Band-Aid’ natural compounds, to help mask the symptoms of sugar-induced gut damage.  This is shockingly scary, since masking symptoms of progressively damaging the Gut is a recipe for severe-chronic disease.

One last note on certain foods effecting the gut during endurance exercise. In addition to simple sugar-carbs, a recent study in 2016 looking at the cycle-run of Ironman 70.3 races, it was highlighted that caffeine (typically in the form of coffee) was the other pre-race morning food consumed that specifically caused issues for lower-gastro issues,  namely  lower abdominal cramps, flatulence and urge to defecate.


Finally, Gulping food while exercising.

The last comment worth mentioning here is with respect to food-design and digestion, while exercising.  There is a disservice going on in the food industry – whereby packaged processed foods are by design made of a texture and consistency that seeks to minimize, even avoid the need to chew food. This is prominent is energy-gels, energy-drinks and almost all energy bars.  Even at rest, the beginning of the breakdown of foods starts in the mouth. Not just the physical breakdown of foods, but that chewing itself triggers the release of critical enzymes in the mouth (and also stomach, small intestine, pancreas…) to begin carbohydrate and fat digestion. The act of gulping, also encourages food to be swallowed ‘with air’ – causing a dilated stomach, commonly triggering belching/burping, and if on-going, stomach-reflux.

Processed energy food and drink products of a ‘fluid-like’ texture enable rapid gulping, where by the cephalic phase (enzymes triggered by taste, smell, texture) of digestion is dramatically minimized. Furthermore ingested foods that are gulped down (with air), run the risk of minimal mouth-time and direct contact with mouth digestive enzymes like lipase (fat) and amylase (carbohydrate).  The elimination of chewing the food, contributes to bloating, gas and cramping symptoms, so common in endurance racing athletes. Furthermore this slows transit and assimilation time of the foods in the stomach and small-intestine, as food misses out on mouth-based enzymatic digestion.

Now this may be OK once, when at rest – but as noted earlier, with exercise diverting blood supply away from the digestive system, and dehydration commonly seen in endurance athletes, the stomach and small-intestine are already struggling to keep digestion working properly.

It’s no wonder gut symptoms wreak havoc on endurance athlete completing races, as undigested carbs and sugars move from the mouth to an under-functioning stomach and small intestine.

How common is this?  No.1 reason for DNFs at ultra-endurance races.


Minimize the ULTRA Gut Impact

The Big 4.






  • Keep cool, Keep hydrated:  The very nature of endurance exercise will raise our body temperature. But using cool water over our body, and in drinking cool-cold water will help to reduce the known effects of exercise (heat)-driven digestive disturbances.  Obviously you need to become well-sensitized to your own sweat output and fluid intake needs – but make sure you test and document this (weight before/after training, minus total fluid intake of training)…and do this for a variety of temperature/humidity conditions so you know how your body needs/processes water.
  • Take L-Glutamine:  To further enhance your body’s resistance to exercise (heat) derived digestive disturbance, include L-Glutamine capsules (2 x 500mg) every hour, for training sessions in hot, or humid weather. A number of studies have shown how L-Glutamine directly minimizes the heat-shock impact, to the digestive system.
  • Avoid high fructose/sugar foods and processed grains in training-racing: Take a look at your training-racing foods and do your homework on what you’re throwing into your body…most of the sugar, grain based products on the market are high in these nasty ingredients.  Eat whole food complex carb-foods (containing mix of carbs, fats, protein AND prebiotic fiber). Download the QuickStart Guide ‘The Fuel Switch’ to learn about foods to eat in ultra racing and training.  Finally test and make a call if caffeine/coffee pre-race has an effect on your gut (cramping, gas, need to ‘go’).
  • Eat foods that make you chew, and avoid others: Real, whole foods need chewing. Any processed food that minimizes chewing will raise the risk of digestive symptoms. Ensure the energy foods used in racing and training require you to chew the food before swallowing. Again you can read more about these foods, by downloading the How-To-Guide ‘The Fuel Switch’.


The Finishing Comment –

An endurance athlete can train for over a year in the preparation for a major ultra-endurance race. It’s amazing how shockingly common Did-Not-Finishes are, in this sport.  Not because of under-training, not because of muscle soreness or tiredness – but simply because of the Ultra gut impact.

Follow the Big 4 above, Minimize the Ultra Gut Impact, and raise your chances of finishing and posting your new personal-best times.

Happy racing and training – Go Longer.