Palatinase is a digestive enzyme in your small intestine that breaks down palatinose (also called isomaltulose) into its two component sugars: glucose and fructose. It works slowly compared to other sugar-digesting enzymes, which is why palatinose produces a gentler rise in blood sugar than table sugar. Palatinase is not actually a standalone enzyme but rather a specific activity of the sucrase-isomaltase complex, a well-studied enzyme anchored to the lining of the small intestine.
How Palatinase Works
Your small intestine is lined with tiny finger-like projections called villi, and on the surface of those villi sit enzymes that break down different sugars. Palatinase is one of these “brush border” enzymes. Its job is to split the bond in palatinose, a naturally occurring sugar found in honey and sugarcane, releasing individual glucose and fructose molecules that can then be absorbed into your bloodstream.
What makes palatinase notable is how slowly it works. When researchers compare the activity levels of different sugar-digesting enzymes in human intestinal tissue, palatinase ranks near the bottom. If you set maltase activity (the enzyme that digests malt sugar) at 100, sucrase activity comes in around 20 and palatinase activity at just 5. That means palatinase digests its sugar roughly four times more slowly than sucrase digests table sugar, and about twenty times more slowly than maltase handles maltose.
Despite this slow pace, palatinose is completely digested and absorbed. It just takes longer, and the digestion tends to happen further down the small intestine rather than right at the top. This has meaningful consequences for blood sugar and energy metabolism.
Its Relationship to Sucrase-Isomaltase
Palatinase is not a separate protein. It is one of several names for the isomaltase portion of the sucrase-isomaltase enzyme complex. This dual enzyme sits on the surface of intestinal cells and handles two jobs: the sucrase half breaks down sucrose (table sugar), while the isomaltase half breaks down isomaltose, palatinose, and certain starch fragments. In scientific literature, you may see the isomaltase side referred to as palatinase, alpha-limit dextrinase, or dextrin 6-alpha-D-glucanohydrolase. These are all names for the same catalytic activity, which specifically cuts alpha-1,6 bonds between sugar molecules.
Why Slow Digestion Matters for Blood Sugar
Because palatinase works slowly, the glucose and fructose from palatinose trickle into your bloodstream gradually rather than arriving in a rush. This produces a lower spike in blood sugar and, critically, a lower spike in insulin. Insulin is the strongest hormonal suppressor of fat burning, so when insulin stays low, your body can continue drawing on fat for energy.
The slow digestion also shifts where in the intestine the sugars are released. With sucrose, most of the glucose and fructose appears in the upper small intestine, where it triggers the release of one type of gut hormone (GIP). With palatinose, more of the sugar reaches the lower small intestine, where it stimulates a different gut hormone (GLP-1) that plays a role in appetite regulation and blood sugar control. This difference in gut hormone signaling is one reason nutritional scientists have taken interest in palatinose as a carbohydrate source.
Importantly, this slower digestion does not cause digestive discomfort. Unlike sugar alcohols or fiber-based sweeteners that can ferment in the gut, palatinose is fully broken down and absorbed. The effect is simply a gentler, more drawn-out process.
Palatinase and Exercise Performance
The slow-release profile of palatinose digestion has attracted attention in sports nutrition. In a randomized, double-blind trial, cyclists who consumed a palatinose-based drink before exercise maintained more stable blood glucose levels during a 90-minute endurance ride compared to those who drank a maltodextrin (fast-digesting carbohydrate) beverage. The palatinose group also burned significantly more fat during exercise, with fat oxidation rates 88% to 99% more likely to be higher than the maltodextrin group.
The practical payoff: the palatinose group finished a subsequent time trial about 2.7% faster and produced 4.6% more power in the final five minutes. The likely mechanism is that lower insulin levels allowed greater fat burning during the steady-state portion of exercise, which spared stored muscle glycogen for the harder effort at the end. The researchers also noted that the common “rebound” drop in blood sugar that happens shortly after starting exercise was substantially reduced with palatinose.
What Happens When Palatinase Is Missing
Because palatinase is part of the sucrase-isomaltase complex, people born without a functional version of this enzyme have a condition called congenital sucrase-isomaltase deficiency (CSID). This genetic condition usually becomes apparent after an infant is weaned onto solid foods, particularly fruits, juices, and grains. Without the enzyme to break these sugars down, the undigested carbohydrates pass into the large intestine, where gut bacteria ferment them and produce gas.
Typical symptoms include stomach cramps, bloating, excessive gas, and diarrhea after eating foods containing sucrose or maltose. In infants and young children, ongoing malabsorption can lead to failure to thrive, meaning the child does not gain weight or grow at the expected rate. Palatinase activity in intestinal tissue is sometimes measured directly through a biopsy. Normal values are considered to be 5 units per gram of tissue or above; levels below that threshold suggest deficiency.
Normal Enzyme Levels
Palatinase activity is measured from a small tissue sample taken from the small intestine, typically during an upper endoscopy. The threshold for normal palatinase activity is at least 5 units per gram of tissue. This test is most commonly ordered when a person, often a child, has unexplained chronic diarrhea, bloating, or poor growth after eating starchy or sugary foods. Low palatinase activity, because it reflects the broader sucrase-isomaltase complex, usually coincides with low sucrase activity as well.