Slow release carbohydrates are a preferred carbohydrate source in human nutrition because of their benefits for blood sugar management and metabolic health: The slow and steady supply of glucose keeps blood sugar levels low and more stable. Less insulin is required and allows to create a better metabolic profile. Hence, as a means to lower glycaemia, slow release carbohydrates can contribute to a healthy diet and support efforts in the prevention and management of non-communicable diseases like diabetes, CVD and obesity.
The availability of fully digestible slow release carbohydrates is limited, though. Most carbohydrates are readily digestible, causing fast and high blood sugar spikes, like highly processed starch, maltodextrins or most common sugars. Isomaltulose is different: As a fully digestible slow release carbohydrate, it supplies the body with glucose in a more balanced and sustained way, with low effect on blood sugar and insulin levels.
The slow release carbohydrate isomaltulose
The particular difference of isomaltulose lies in its slow and sustained release of carbohydrate energy. The slow release properties of isomaltulose are well demonstrated and reflected in its physiology:
- Slow digestion by intestinal enzymes: Being a disaccharide carbohydrate, isomaltulose needs to be split by intestinal enzymes prior to absorption. Its digestion involves the enzyme isomaltase, which is located in the intestinal wall (as part of the sucrose-isomaltase enzyme complex) and otherwise involved in the digestion of starch. Enzyme kinetic data reveal that the digestion of isomaltulose is much slower than that of sucrose (with a difference in Vmax by a factor of 4 to 5).
- Digestion and absorption along the small intestine: Observations on the different incretin response to isomaltulose and sucrose further illustrate that the enzymatic cleavage of isomaltulose and subsequent absorption is a slow process that occurs along the entire length of the small intestine, including also more distal parts: Unlike sucrose, isomaltulose digestion triggers a low GIP release from K-cells in the upper part of the small intestine, and a higher GLP-1 release from L-cells in the lower part of the small intestine (Maeda et al 2013, Ang & Linn 2014, Keyhani-Nejad et al 2016). Despite is slow intestina release, isomaltulose is a fully digestible carbohydrate (Holub et al 2010). The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are involved in blood glucose regulation after food intake, stimulating glucose-dependent insulin secretion.
- Low blood glucose response: The blood sugar response curve of isomaltulose reflects the slow and sustained intestinal glucose release. It shows a slower and overall lower rise in blood sugar levels over a longer period of time. With its low effect on blood sugar levels (GI: 32) and insulin release, isomaltulose creates a metabolic profile that favors fat burning and supports normal blood glucose control. Reducing glycemia of the diet has been linked with health benefits.
- Incretin response and metabolic health: Emerging science postulates that the hormone GIP plays a key role in the metabolic effects and quality of carbohydrates in human nutrition (see review of Pfeiffer & Keyhani-Nejad 2018). GIP release is triggered by monosaccharides, which are either present as such in the food or result from rapid digestion of readily available carbohydrates by intestinal enzymes. Its physiological functions largely promote the storage of energy in the body.
The low effect of isomaltulose on GIP release has been linked with less fat storage in the liver and resulting positive effects on insulin sensitivity in a well-designed animal study by Keyhani-Nejad et al 2015), suggesting its potential as a nutritional strategy in the prevention of non-alcoholic fatty liver and insulin resistance. Moreover, the intake of isomaltulose for 4 to 20 weeks in controlled diet studies improved blood glucose control and insulin sensitivity in humans, while sucrose showed no such effect. Reductions in fasting blood glucose and improvements in insulin resistance (HOMA-IR) have been observed in healthy persons or those with poor insulin sensitivity (Holub et al 2010, Okuno et al 2010, Sakuma et al 2009, Yamori et al 2007). Emerging science proposes that isomaltulose may even have positive effects on arterial stiffness, which was observed in parallel with higher GLP-1 levels and higher insulin sensitivity in a study with active healthy men who consumed isomaltulose- instead of sucrose-drinks (Keller et al 2016).
Slow release carbohydrates like isomaltulose can contribute to lower blood sugar levels when being consumed as preferred carbohydrate choices in a healthy diet. They support blood sugar management and metabolic health in people who want to care for their blood sugar levels (see health conscious eaters) or need to care for their blood sugar levels, for instance during pregnancy, or for health reasons when facing raised blood sugar levels and the metabolic syndrome or when being diagnosed with diabetes mellitus.
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Holub I, Gostner A, Theis S, Nosek L, Kudlich T, Melcher R, Scheppach W (2010) Novel findings on the metabolic effects of the low glycaemic carbohydrate isomaltulose (Palatinose™). Br J Nutr 103(12):1730–1737. http://www.ncbi.nlm.nih.gov/pubmed/20211041
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