The study, funded by Suntory Beverage & Food NZ Ltd, compared the effects of a sucrose-based caffeinated beverage with an isomaltulose-based caffeinated beverage that also contained a small amount of l-theanine.
Rather than evaluating which drink was superior, the researchers from the University of Auckland in New Zealand employed a “non-inferiority design”, a type of clinical trial aimed at demonstrating that a new treatment is not worse than an existing treatment.
“Non-inferiority between sucrose and isomaltulose was shown for all assessed cognitive domains except for composite memory, verbal memory, and visual memory,” they wrote in the journal Nutrients.
“These findings hold relevance for the health of regular consumers of sugar-sweetened beverages and for commercial manufacturers.”
A healthier sugar alternative
Studies suggest that isomaltulose is a healthier sugar alternative than sucrose. Carbohydrates such as sucrose are included in energy drinks along with caffeine to support physical activity and mental focus.
However, the glucose and insulin response that occurs when energy drinks are consumed can be a risk factor for chronic diseases such as type 2 diabetes.
Isomaltulose, often marketed as Palatinose, is digested more slowly, attenuating insulin response, therefore potentially resulting in a smaller “sugar crash” effect.
Additionally, isomaltulose may have dental benefits because its stable structure is resistant to breakdown by plaque bacteria, making it non-cariogenic.
“Given the associations between glycaemic index, postprandial glucose levels, and markers of cardiovascular disease, as well as metabolic syndrome, isomaltulose-based beverages may provide a lower-risk option for frequent consumers of energy drinks, particularly those with pre-existing health conditions,” the researchers wrote, noting that future research in those populations is required.
Study details
The study assigned 30 adult participants to consume a caffeinated isomaltulose drink, a caffeinated sucrose drink, or a placebo drink after at least three hours of fasting.
All drinks contained vitamin C and B vitamins, and the isomaltose drink contained 77.5 mg of l-theanine.
The crossover study design entailed participants completing all three experimental drinks, with a 1-week gap between them. The order of the remaining two experiments was randomized.
The researchers measured plasma insulin and blood glucose levels and assessed cognitive function, fatigue, and mood. The results revealed that “circulating glucose was greater after ingesting sucrose compared to isomaltulose and placebo beverages,” and the rise in insulin was greater with sucrose than with isomaltulose.
“Non-inferiority was shown between isomaltulose and sucrose for the composite neurocognitive index score,” the researchers wrote. They also found that the sensation of tiredness after consuming isomaltulose wasn’t inferior to that of the sucrose drink.
“However, neither caffeinated beverage consistently improved cognition compared to a placebo, limiting broader generalisation”, they concluded.
The authors noted the study limitations, including the fact that they couldn’t rule out the effects of l-theanine in the isomaltulose drink, which could potentially improve some aspects of cognition when ingested with caffeine.
Source: Nutrients 2026, 18(7), 1163; https://doi.org/10.3390/nu18071163. “Isomaltulose-Based Stimulant Beverages Can Improve Postprandial Metabolic Responses Without Compromising Cognitive Benefits Associated with Caffeinated Energy Drinks.” Authors: P.M. Bloomfield et al.
