Hannah L Notbohm, Joshua F Feuerbacher, Finn Papendorf, Nils Friese, Mats W Jacobs, Hans-Georg Predel, Jonas Zacher, Wilhelm Bloch, Moritz Schumann
Journal: Journal of the International Society of Sports Nutrition 2021;18(1):38
PMID: 34001166
Isomaltulose is a low-glycaemic index carbohydrate that lowers insulin and glucose levels postprandially. The benefits of taking Isomaltulose in an exercise setting are not well studied. This double-blinded, randomised, crossover study evaluated the effects of Isomaltulose intake on metabolic responses, hormonal responses, exercise performance and gastrointestinal disturbances in runners. Twenty-one male recreational endurance runners took part in four separate experimental sessions to compare Isomaltulose to maltodextrin and glucose. Fat and carbohydrate oxidation rates were not different among groups. This might be because the lower dose of Isomaltulose (50g) was used in this trial. Compared to glucose and maltodextrin, isomaltulose lowered metabolic and hormonal responses to exercise. In the study, Isomaltulose, glucose, and maltodextrin did not differ in exercise performance or gastrointestinal disturbances. A higher dose may be needed in order to demonstrate exercise performance, but caution should be exercised since a higher dose may cause gastrointestinal upset. A robust investigation of Isomalulose dose and its effects on glucose, insulin, and glucose-dependent insulinotropic polypeptides is required to determine if exercise leads to hypoglycaemia in the clinical population. Healthcare practitioners can use the findings of this study to understand the advantageous effects of 50g Isomaltulose in regulating glucose, insulin and glucose-dependent insulinotropic polypeptide during aerobic exercise.
BACKGROUND
Isomaltulose has been discussed as a low glycaemic carbohydrate but evidence concerning performance benefits and physiological responses has produced varying results. Therefore, we primarily aimed to investigate the effects of isomaltulose ingestion compared to glucose and maltodextrin on fat and carbohydrate oxidation rates, blood glucose levels and serum hormone concentrations of insulin and glucose-dependent insulinotropic polypeptide (GIP). As secondary aims, we assessed running performance and gastrointestinal discomfort.
METHODS
Twenty-one male recreational endurance runners performed a 70-min constant load trial at 70% maximal running speed (V), followed by a time to exhaustion (TTE) test at 85% V after ingesting either 50 g isomaltulose, maltodextrin or glucose. Fat and carbohydrate oxidation rates were calculated from spiroergometric data. Venous blood samples for measurement of GIP and insulin were drawn before, after the constant load trial and after the TTE. Capillary blood samples for glucose concentrations and subjective feeling of gastrointestinal discomfort were collected every 10 min during the constant load trial.
RESULTS
No between-condition differences were observed in the area under the curve analysis of fat (p = 0.576) and carbohydrate oxidation rates (p = 0.887). Isomaltulose ingestion led to lower baseline postprandial concentrations of blood glucose compared to maltodextrin (percent change [95% confidence interval], - 16.7% [- 21.8,-11.6], p < 0.001) and glucose (- 11.5% [- 17.3,-5.7], p = 0.001). Similarly, insulin and GIP concentrations were also lower following isomaltulose ingestion compared to maltodextrin (- 40.3% [- 50.5,-30.0], p = 0.001 and - 69.1% [- 74.3,-63.8], p < 0.001, respectively) and glucose (- 32.6% [- 43.9,-21.2], p = 0.012 and - 55.8% [- 70.7,-40.9], p < 0.001, respectively). Furthermore, glucose fluctuation was lower after isomaltulose ingestion compared to maltodextrin (- 26.0% [- 34.2,-17.8], p < 0.001) and glucose (- 17.4% [- 29.1,-5.6], p < 0.001). However, during and after exercise, no between-condition differences for glucose (p = 0.872), insulin (p = 0.503) and GIP (p = 0.244) were observed. No between-condition differences were found for TTE (p = 0.876) or gastrointestinal discomfort (p = 0.119).
CONCLUSION
Isomaltulose ingestion led to lower baseline postprandial concentrations of glucose, insulin and GIP compared to maltodextrin and glucose. Consequently, blood glucose fluctuations were lower during treadmill running after isomaltulose ingestion, while no between-condition differences were observed for CHO and fat oxidation rates, treadmill running performance and gastrointestinal discomfort. Further research is required to provide specific guidelines on supplementing isomaltulose in performance and health settings.
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