High carbohydrate diets with varied FODMAP content on the development of exercise-associated gastrointestinal symptoms during endurance exercise in endurance-trained athletes

Participants are provided with a high carbohydrate high FODMAP (HC-HFOD) or high carbohydrate low FODMAP (HC-LFOD) diet 48-h before endurance exercise. The HC-HFOD is the comparator diet, and the HC-LFOD is the intervention. The HC-HFOD diet provided was 813 g +/- 101 g total carbohydrate daily (11.3 +/- 1.0 g/kg bodyweight/d) or 72% of carbohydrate with a high FODMAP load (54.8 +/- 10.5 g daily). The HC-LFOD diet provided was 888 g +/- 71 g total carbohydrate daily (12.6 +/- 2.0 g/kg bodyweight/d) or 73% of carbohydrate with a low FODMAP load (3.0 +/- 0.2 g daily). Participants were provided with all meals, snacks, and drinks, excluding water, for the 48-h prior to the exercise test and the test day breakfast. Meals were designed, prepared and administered by a research registered dietitian. Examples of the meals and snacks for the diets are: HC-HFOD diet (note the HC-LFOD diet has a similar meal pattern except all HFOD meals or snacks were designed to be LFOD - e.g., LFOD fruity oats - had less sugar and less raisins or cows milk was replaced for lactose-free milk). Breakfast: HFOD fruity oats (oats, quinoa, raisins, brown sugar) Low-fat cow’s milk (1%) (250 mL) Greek yoghurt (200 g) Honey (25 g) Morning Tea: Spelt sourdough bread (2 slices) Butter (10 g) Strawberry jam (10 g) Kiwifruit (2 medium green fruit) Lunch: HFOD vegetable soup (red capsicum, zucchini, carrot, corn, barley, potato, LFOD stock cubes, garlic, onion) Spelt sourdough bread (2 slices) Greek yoghurt (200 g) Afternoon Tea: Orange (1 medium fruit) HFOD creamed rice (white rice, white sugar, low-fat cow’s milk, butter, vanilla essence, cinnamon) Dinner: HFOD meat sauce (beef mince, tomato pasta, canned tomatoes, carrot, olive oil, onion, garlic, salt) Wheat pasta cooked (400 g) Cheddar cheese grated (30 g) Cranberry juice (300 mL) Supper: Cranberry juice (300 mL) Raisins (40 g) Drinks: Powerade (about 2L daily) Plus additional Dextrose (if required) Smoothie (Low-fat cow’s milk, dextrose, protein powder, blueberries, honey). Pre-Exercise breakfast of trial days was the same for both trials: LFOD fruity oats Lactose-free yoghurt (200 g) Lactose-free cow’s milk (250 mL) Maple syrup (25 g) Participants received the diet for 48-h before exercise (i.e., 2 days before) and the breakfast for the trial day. During the 3-h seated recovery period, participants were provided with a recovery meal (after 2 -h), plus some fruit. The diets were based on a carbohydrate loading protocol (or high carbohydrate diet), as recommended for endurance athletes by sports nutrition guidelines. Diets were based on 10-12g carbohydrate/kg of body mass; only the FODMAP content varied between diets. To ensure food adherence, participants monitored all food and drink consumed in a food log. A research dietitian reviewed and confirmed the food log with participants. As this was a cross-over trial, there was a wash-out period of 7 days between trials.