What's (Not) in Your Supplement? An Energy and Macronutrient Analysis of Commercially Available Carbohydrate Gels.

Carbohydrate (CHO) gels are a staple among endurance athletes. When ingested during competition, CHO gels can improve endurance performance by acting as an external energy substrate, sparing endogenous glycogen, mitigating the risk of hypoglycemia, and engaging the central nervous system via receptors in the mouth and gastrointestinal tract. However, published studies and a growing number of anecdotal reports have raised concerns about possible energy and macronutrient deficiencies in several products. We therefore performed a content analysis on CHO gels from Gu Energy, Honey Stinger, Hüma, Maurten, Näak, Precision Fuel, Science in Sport, and Spring Energy. On average, products contained significantly less energy than stated on the labels (n = 8, p = .047, large effect) but with no discrepancy in CHO content (n = 8, p = .219, medium effect). Bland-Altman analyses revealed a systematic bias toward less energy and CHO in measured samples relative to the label-derived nutritional information. Moreover, the Spring Energy product fell outside the 95% limits of agreement for both energy and CHO, containing ∼71% less energy (53 vs. 180 kcal) and ∼72% less CHO (12.5 vs. 45 g) than stated on the label. A follow-up analysis revealed similar discrepancies in several Spring Energy products from multiple lots. These findings have performance, clinical, and legal implications.