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.
What’s (Not) in Your Supplement? An Energy and Macronutrient Analysis of Commercially Available Carbohydrate Gels
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Burke https://orcid.org/0000-0001-8866-5637
Tiller (nicholas.tiller@lundquist.org) is corresponding author, https://orcid.org/0000-0001-8429-658X
In 1924, researchers discovered that runners at the Boston Marathon ran considerably quicker when they consumed carbohydrates (CHO) as confectionary during the race. In the century since this study, CHO supplements have been extensively researched and highly commercialized, with drinks, gels, and candies sold around the world.
Carbohydrates are among the few products in the lucrative world of dietary supplements that are supported by scientific evidence (e.g., Burke et al., 2011). Eating or drinking CHO during endurance exercise may improve performance by providing the body with energy, sparing the body’s internal CHO stores, and helping to maintain blood sugar levels. Of all CHO supplements, gels are among the most popular. These semiliquid substances are usually made of simple sugars. They are portable, easy to store, and contain CHO in premeasured amounts, making it easy for athletes to fuel on the go. What’s more, people with diabetes—a medical condition where the body has trouble controlling blood sugar levels—sometimes use CHO gels when their blood sugar gets too low.
However, there is growing concern that various sports foods and supplements may not contain the nutrients they claim, prompted by various studies and an increasing number of athlete statements. For instance, research on whey protein bars and powders, fish oils, and vitamin D, among many other supplements reveals considerable shortfalls in the products’ measured versus stated amounts—far outside the acceptable range stated by United States, Canadian, and European regulators. With CHO gels, athletes have voiced their concerns about one brand in particular (Burgess & Ohm, 2024), complaining of fluctuating energy levels when using the product during exercise, noting lower-than-expected feelings of fullness with regular consumption, and an unexpected consistency and taste relative to the ingredient profile. If shortfalls in commercial CHO gels exist, it could have major implications on performance and health.
To provide clarity on this issue, we selected eight brands of CHO gels that we perceived to be among the most popular with athletes and sent them to an accredited laboratory to have their contents analyzed. The brands were Gu Energy, Honey Stinger, Hüma, Maurten 100, Näak, Precision Fuel, Science in Sport, and Spring Energy. The lab used a technique called high-pressure liquid chromatography with tandem mass spectrometry, whereby each gel was separated into its various components (e.g., CHO, proteins, and fats), and the specific number of molecules identified based on their mass. The technique allowed us to accurately determine each gel’s total CHO and energy content.
On average, the eight brands of CHO gel weighed the same as expected based on the product label, and there was no overall (average) difference in stated versus actual CHO content. The measured energy content, however, was significantly lower than stated. Of course, looking at the results overall doesn’t allow us to identify outliers in the data. We therefore performed a follow-up analysis to assess the gels individually. Nearly all of the products (7/8) had energy and CHO values within 20% of that stated on the label, thus conforming to United States, Canadian, and European regulations. However, Spring Energy’s Awesome Sauce gel was a statistical outlier, containing 71% less energy than stated on the label (53.0 vs. 180.0 kcal) and 72% less CHO (12.5 vs. 45.0 g).
Due to the large shortfall in energy and CHO, we performed a follow-up analysis on three Spring Energy products: Awesome Sauce, Hill Aid, and Canaberry, totaling nine gels from multiple lots to test if it was an issue isolated to a single batch. We found a similar trend for all products: compared with the labels, the gels contained considerably less energy (range 57%–71%), CHO (range 43%–72%), and sodium (74%–84%).
The implications could be profound. Athletes using these products during exercise would experience a gross mismatch between their perceived and actual energy and CHO intake. This could predispose them to early fatigue and low blood sugar and compromise their performance. By underconsuming sodium, athletes competing in very long races (e.g., ultramarathon) or in hot and humid conditions may be at greater risk for low blood sodium—a potentially fatal medical condition. Last, people with diabetes require precise and consistent information about the CHO and sugar content of their food. The discrepancy we identified could have serious consequences for blood sugar control, and we recommend that individuals avoid products they cannot rely on
Spring Energy has since reformulated its product line, stating that Awesome Sauce now contains 180 calories, 28 g of CHO, 7 g of fat, and 1 g of protein. However, our data serve as a cautionary tale for athletes. We urge them to remain vigilant, carefully consider the content and quality of their foods and supplements, and generally take more ownership of their sports nutrition. It is also a cue for product manufacturers to pay closer attention to their production values and quality control.
References
Burke, L. M., Hawley, J. A., Wong, S. H. S., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29 Suppl 1, S17–27.
Burgess, B., & Ohm, J. (2024, June). Investigation: Lab Tests Confirm Spring Energy Misrepresents Carbs and Calories, 7 Other Brands Have Accurate Labels. iRunFar. https://www.irunfar.com/spring-energy-awesome-sauce-gel-controversy-lab-results
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