Sports Nutrition for Food-Sensitive Athletes

Tamara Duker Freuman

As triathalon season approaches each year, my patient roster becomes peppered with endurance athletes emerging from the winter hiatus. As they look ahead to triathlons, half-marathons, marathons and other highly-competitive events, questions arise about the beverages, bars and energy shots they should use to fuel these athletic endeavors.

[See Performance Foods: What and When to Eat Before Your Next Workout.]

I've reported previously about a category of poorly-absorbed carbohydrates called FODMAPs, which range from fructose and lactose to sugar alcohols (or polyols) and bean-derived galacto-oligosaccharides (GOS). In susceptible people--and particularly in larger doses--these carbs can trigger symptoms like gas, bloating and diarrhea. As it turns out, sports nutrition products are generally loaded with high-FODMAP ingredients.

As a result, sports nutrition products are terribly difficult to navigate for endurance athletes with Irritable Bowel Syndrome (IBS) or other food sensitivities. To complicate matters, many of these products are sold as dietary supplements rather than as food; their labels, therefore, may not disclose all the details one needs to decipher what's actually in them and at what levels. What's a sensitive-bellied Ironman to do?

[See Crazy for Exercise: Are We Overdoing It?]

-- Learn the lingo: High-FODMAP ingredients hide behind other terms on ingredient labels, particularly in sports nutrition products. Lactose isn't likely to be listed on a label, but you'll be getting plenty of it in a product with whey, whey protein concentrate, milk protein concentrate or (powdered) milk at the top of the ingredient list.

Fructose is easily recognizable as a stand-alone ingredient or within high-fructose corn syrup--but lurks undercover in ingredients like invert sugar; inulin/chicory root extract; fruit juice concentrates from apple, orange, pear or grape; agave nectar; and fructo-oligosaccharides (FOS). "Low carb" and "reduced sugar" are code words for "sweetened artificially," so be on the lookout for sugar alcohols like xylitol, sorbitol, erythritol or maltitol--these can create bloating and diarrhea. Sucralose, while not technically a FODMAP, can also cause gastrointestinal upset in some, particularly at doses in the 5- to 10-gram range.

-- Take stock of your food sensitivities: If you rely heavily on sports nutrition products but find many don't agree with your stomach, it may be worth getting tested for lactose intolerance, fructose intolerance and/or celiac disease to help pinpoint specific ingredients you may need to avoid.

[See Food Intolerance: Fact and Fiction.]

If you're not fructose intolerant, there's no need to avoid the fructose-containing FODMAPs. If you are fructose intolerant, you'll want to avoid both fructose and sugar alcohols. The more data you have, the easier it will be to zero in on products you're able to tolerate. A qualified registered dietitian can help you assess symptoms as they relate to the foods you eat to narrow down which food intolerances may be worth testing for.

-- Seek out the safest ingredients: Among milk-based proteins, whey protein isolate (WPI) and calcium caesinate have the least lactose and are generally well-tolerated by digestively-sensitive athletes. Other low-FODMAP protein sources include rice, egg, soy protein isolate (but not soy protein concentrate) and nuts.

Hemp protein is as yet untested by the FODMAP research gurus, so no guidance is available at this time. Complex carbs like maltodextrin, rice dextrins, tapioca and oat flour are tummy-friendly sources of sustained energy.

[See Food and Mood: 6 Ways Your Diet Affects How You Feel.]

Regarding simple sugars for rapid-release energy, glucose (sometimes listed as dextrose), sucrose, brown rice syrup and cane syrup are your best choices. Among non-caloric sweeteners, the most digestively-friendly include aspartame and acesulfame potassium, though whether to consume artificial sweeteners at all is certainly a matter of personal preference. Stevia, a natural calorie-free sweetener, is generally well-tolerated by most.

-- Consider the cumulative dose: If sorbitol is listed as the last ingredient in a protein powder of which you only use a single serving, it may be tolerated just fine on its own. But if that shake comes after three hours of training, during which you've been pounding fructose-rich energy gels and sports drinks, it may put you over the edge.

When it comes to FODMAPs, cumulative dose matters a lot. Look at the full array of sports nutrition products you use--electrolyte drinks, bars, protein shakes, energy gels or chews and consider the cumulative "FODMAP-iness" of your overall regimen. Test out your full nutrition program adequately during training to determine which combination of products you tolerate, and don't stray from the regimen that works best on race day.

It's worth mentioning that these highly functional sports nutrition products--electrolyte beverages, protein shakes, energy chews, gels and shots--are formulated for endurance athletes. For us mere mortals sweating through the occasional 10K or lifting weights at the gym a few times per week, specialized sports nutrition products aren't likely to be necessary.

[See The Energy Drink, Deconstructed.]

Replenishing fluids, salt and carbs during a 90-minute run can easily be done with water and a fanny pack stocked with salty pretzel sticks. Replenishing protein and carbs after recreational weight lifting is effectively accomplished with chocolate milk (lactose-free if necessary) or a turkey sandwich.

Frankly, protein shakes and bars with 20 to 30 grams of protein per serving are overkill for the vast majority of people. Real, minimally-processed food is more likely to be tolerated digestively and should be every bit as "functional" as designer sports nutrition supplements for healthy, fit people engaging in 30- to 90-minute bouts of non-competitive physical activity.

Lastly, if you are an athlete experiencing troubling gastrointestinal symptoms--especially blood in the stool or vomiting--don't assume that diet alone is the only factor to consider. A high fitness level doesn't discount the possibility of other serious health conditions.

[See Top-Ranked Hospitals for Gastroenterology.]

Hungry for more? Write to with your questions, concerns, and feedback.

Tamara Duker Freuman, MS, RD, CDN, is a NYC-based registered dietitian whose clinical practice specializes in digestive disorders, Celiac Disease, and food intolerances. Her personal blog,, focuses on healthy eating and gluten-free living.