Also known as: Palatinose, Slow carb, Low GI carbohydrate, Sucrose isomer
EnduranceGood evidence
A carbohydrate made by rearranging sucrose so the body breaks it down slowly. Supplies the same energy as sugar with a far gentler blood glucose curve, which makes it useful for long efforts.
Typical dose
30.0–60.0 g per day
45-90 minutes pre-session, or during longer efforts
What it is
Isomaltulose is a disaccharide made from sucrose by enzymatically rearranging the bond between its glucose and fructose units. It occurs naturally in honey and sugar cane extract in small amounts.
That rearranged bond is harder for the enzymes in the small intestine to break, so digestion takes considerably longer than for ordinary sugar. The energy content is identical; the delivery is spread out.
It is roughly half as sweet as sucrose, which is useful in formulation, and it is not fermented by the bacteria that cause tooth decay.
How it works
The enzyme that splits isomaltulose works around four to five times more slowly than the one handling sucrose. Glucose therefore enters the bloodstream gradually rather than in a spike.
The result is a lower and flatter blood glucose and insulin response, with the same total energy delivered over a longer period.
For endurance work, lower insulin means less suppression of fat oxidation, so the body continues drawing on fat alongside the incoming carbohydrate. That combination is the main argument for using it during long sessions.
What the evidence shows
The slower digestion and flatter glucose response are well demonstrated and not in dispute. Isomaltulose reliably produces a lower glycaemic response than sucrose or maltodextrin.
Exercise research has reported higher fat oxidation during exercise when isomaltulose is used in place of high-glycaemic carbohydrate, with some trials also reporting improved performance in longer efforts.
Findings on performance are mixed rather than uniform, and the advantage appears specific to longer sessions where the flatter curve matters. For short high-intensity work, faster carbohydrate is the better choice.
Dosing
For fuelling during exercise, 30 to 60 g per hour, in line with general carbohydrate guidance. It can also be taken 45 to 90 minutes before a session as a slower-releasing pre-workout carbohydrate.
Because absorption is slower, it suits longer steady efforts better than short intense ones. For a sprint session or a heavy lifting workout, faster carbohydrate is more appropriate.
The slower digestion has a practical downside: more of it is still in the gut for longer, which can cause discomfort at high intake rates. Combining it with a faster carbohydrate source is a common approach, and gut tolerance improves with practice.
At a glance
Common forms
Palatinose, Generic isomaltulose, Within endurance drinks and gels, Combined with maltodextrin
Half-life / duration
Digested over several hours rather than minutes
Timing
45-90 minutes pre-session, or during longer efforts
Competition status
Permitted — not on the WADA Prohibited List
Category
Endurance
Safety and side effects
Isomaltulose is a food carbohydrate and is safe. It is fully digested rather than fermented, so it causes less gas than sugar alcohols or fermentable fibres.
At high intake rates during exercise, the slower digestion means more remains in the gut, and discomfort is the main complaint. Building up tolerance in training rather than trialling it on race day is sensible.
It contains glucose and fructose and supplies the same calories as sugar, so it should be counted as carbohydrate rather than treated as a free ingredient. Anyone who cannot tolerate fructose should avoid it.
Who should avoid it
Avoid if you cannot tolerate fructose. Count it as carbohydrate, since it supplies the same energy as sugar. Build up intake in training rather than trialling high rates on race day. Take care if your blood sugar is being managed, and speak to your doctor first in that case.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
