IngredientsMaltase bears the formal enzyme commission number EC 3.2.1.20 and is also known by a range of synonyms including alpha-glucosidase, glucoinvertase, glucosidosucrase, maltase-glucoamylase, alpha-glucopyranosidase, glucosidoinvertase, alpha-D-glucosidase, alpha-glucoside hydrolase, alpha-1,4-glucosidase, and alpha-D-glucoside glucohydrolase. It is a type of alpha-glucosidase enzyme found in the small intestine's brush border. Maltase is a member of the GH13 (Glycoside hydrolase family 13) of intestinal enzymes responsible for transforming complex carbohydrates' glucosidase linkages into simple glucose molecules. It is defined as an enzyme that catalyzes the hydrolysis of the disaccharide maltose into simple sugar glucose.
In the human genome, the term "maltase" encompasses several related but distinct enzyme entities encoded by different genes. The MGAM gene encodes maltase-glucoamylase, a brush border membrane enzyme that plays a role in the final steps of digestion of starch. The protein has two catalytic sites identical to those of sucrase-isomaltase, but the proteins are only 59% homologous. Both are members of glycosyl hydrolase family 31, which has a variety of substrate specificities. A second form, acid maltase (also called acid alpha-glucosidase or lysosomal alpha-glucosidase), is encoded by the GAA gene and operates in a completely different cellular compartment. Pompe's disease is a metabolic myopathy caused by a deficiency of acid alpha-glucosidase (GAA), also called acid maltase, an enzyme that degrades lysosomal glycogen.
Maltases are specialised alpha-glucosidases — exo-acting enzymes that release alpha-D-glucose from the non-reducing end of their substrates — that act preferentially on maltose, producing glucose. Maltases are also able to release alpha-D-glucose from the non-reducing end of generic alpha-glucosidase substrates such as 4-nitrophenyl alpha-D-glucopyranoside (pNPG), but at rates lower than that for maltose hydrolysis.
Maltase is an enzyme that catalyzes the hydrolysis of the disaccharide maltose to the simple sugar glucose. The enzyme is found in plants, bacteria, and yeast; in humans and other vertebrates it is thought to be synthesized by cells of the mucous membrane lining the intestinal wall.
In plants, maltase plays an especially prominent role during grain germination. During germination and early seedling growth of barley (Hordeum vulgare), maltase is responsible for the conversion of maltose produced by starch degradation in the endosperm to glucose for seedling growth. Despite the potential relevance of this enzyme for malting and the production of alcoholic beverages, neither the nature nor the role of maltase is fully understood. Research has shown that all of the maltase activity in the barley endosperm can be accounted for by a single gene, Agl97. Multiple forms of the enzyme most likely arise from proteolysis and other post-translational modifications.
In yeasts and fungi, maltase activity is essential for fermentation of maltose derived from starch. In the human intestine, human maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) are small intestinal enzymes that work concurrently to hydrolyze the mixture of linear alpha-1,4- and branched alpha-1,6-oligosaccharide substrates that typically make up terminal starch digestion products.
The NIH Office of Dietary Supplements Dietary Supplement Label Database (DSLD) classifies maltase under the category "Enzyme." Related terms on supplement labels include "Acid maltase" and "Maltase." In the dietary supplement industry, maltase is commonly obtained through microbial fermentation. The vegetarian supplement form of this enzyme is produced by a natural fermentation process of Aspergillus oryzae. Maltase is commonly included as an ingredient within supplements, such as in digestive enzyme formulas, to support individuals who experience difficulty digesting starches and maltose-containing foods. Maltase is also regularly used within the food and beverage industry for brewing, baking (e.g., for bread), and malt processing to aid the conversion of complex carbohydrates into fermentable sugars. Supplement products appear in capsule, tablet, powder, and chewable tablet forms, typically within multi-enzyme blends rather than as single-ingredient preparations.
The enzyme maltase itself was not identified or named in historical periods; however, the foods and preparations that are richest in natural maltase activity — principally malted grains — have a very long history of human use. Starch degradation in the endosperm of barley seedlings provides the glucose substrate for the early growth of the seedling. Conversion of starch polymers to glucose involves four classes of enzyme: alpha-amylase, beta-amylase, limit-dextrinase, and maltase. While the first three of these classes are well understood, relatively little is known about maltase. Its nature, its role in endosperm starch degradation, and its importance for brewing and distilling remain subjects of debate.
The malting of barley and related cereals — a process that activates and concentrates these starch-degrading enzymes, including maltase — is one of humanity's oldest food technologies and underlies the production of beer and fermented grain beverages across multiple ancient civilizations, including Mesopotamian, Egyptian, and later European traditions. Barley (Hordeum vulgare) is one of the most important ingredients in beer brewing. Malting is a critical step in beer production, alongside mashing and fermentation. It is a form of controlled grain germination that stabilizes barley seeds, leading to physical and chemical changes. Maltase, invertase, and alpha-glucosidase contributed to the starch hydrolysis process during mashing.
Malt extracts — liquid or solid concentrates derived from sprouted, dried barley grain — were widely used in 19th- and early 20th-century Western medicine and popular nutrition as tonics and restorative preparations, particularly for convalescents, infants, and the elderly. These preparations were implicitly leveraging the enzyme activity present in malted grain, including maltase activity. The formal scientific isolation and characterization of individual digestive enzymes, including maltase, emerged from research in the late 19th century as biochemistry developed as a discipline.
The deduced 1,857-amino acid MGA protein has a putative type II membrane anchor, 2 WIDMNE catalytic sites characteristic of carbohydrate hydrolases, and 2 glycosyl hydrolase family 31 signature 2 sequences. MGA also has 19 potential N-glycosylation sites and 253 potential O-glycosylation sites. The MGA protein shares 59% sequence identity with sucrase-isomaltase (SI). RT-PCR detected MGA expression in human small intestine, granulocyte, and kidney but not in salivary gland or pancreas.
MGAM consists of two subunits with differing substrate specificity. Recombinant enzyme studies have shown that its N-terminal catalytic domain has highest activity against maltose, while the C-terminal domain has a broader substrate specificity and activity against glucose oligomers. In the small intestine, this enzyme works in synergy with sucrase-isomaltase and alpha-amylase to digest the full range of dietary starches.
Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities.
MGAM and SI are each composed of duplicated catalytic domains, N- and C-terminal, which display overlapping substrate specificities. The N-terminal catalytic domain of human MGAM (ntMGAM) has a preference for short linear alpha-1,4-oligosaccharides, whereas N-terminal SI (ntSI) has a broader specificity for both alpha-1,4- and alpha-1,6-oligosaccharides.
The N-terminal maltase domain (ntMGAM) mainly hydrolyzes short length oligomaltoses having two to four glucose residues. More recent structural biology work has illuminated the interaction between these two major mucosal disaccharidases. The two major intestinal alpha-glycosidases, sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM), are active towards alpha-1,4 glycosidic linkages that prevail in starch. These enzymes share striking structural similarities and follow similar biosynthetic pathways. SI interacts avidly with MGAM concomitant with a hetero-complex assembly in the brush border membranes. This interaction is resistant to detergents such as Triton X-100 or Triton X-100 in combination with sodium deoxycholate. By contrast, inclusion of sodium deoxycholate into the solubilization buffer reduces the enzymatic activities towards sucrose and maltose substantially, most likely due to alterations in the quaternary structure of either enzyme.
The mechanism of all Family GH13 enzymes is the hydrolysis of alpha-glucosidase linkage. Maltase is an exo-acting hydrolase: it cleaves glucose units sequentially from the non-reducing end of maltose and short oligosaccharide chains via an acid-base catalytic mechanism involving a pair of conserved aspartate residues in the active site. In humans, both the N-terminal catalytic domain (NtMGAM) and the C-terminal catalytic domain (CtMGAM) of small intestinal maltase-glucoamylase (MGAM) are alpha-glycosidases that catalyze the hydrolysis of alpha-(1→4) glycosidic linkages in the process of starch digestion, and are considered to be the main therapeutic targets for type 2 diabetes.
Lysosomal acid maltase or GAA hydrolyzes linear alpha-1,4 glucosidic linkages in substrates ranging from large polymers (glycogen) to maltose and the artificial substrate 4-methylumbelliferyl-alpha-D-glucoside. This enzyme, located in lysosomes rather than the intestinal brush border, is responsible for intracellular glycogen catabolism and represents a functionally and genetically separate entity from the brush-border MGAM, despite sharing alpha-glucosidase activity.
During the digestion process, starch is partially transformed into maltose by salivary or pancreatic enzymes called amylases; maltase is secreted by the intestine and then converts maltose into glucose. The body either uses the glucose or stores it as glycogen, also known as animal starch, in the liver. The nutritional and clinical importance of small intestinal maltase and isomaltase activities are due to their crucial role in the digestion of food starches to absorbable free glucose.
While unequivocal data on the existence of genetically-determined carbohydrate malabsorption due to MGAM alone do not exist, the maltase and glucoamylase activities of this enzyme complex are substantially reduced in many cases of congenital sucrase-isomaltase deficiency (CSID). One possible explanation for this reduction is that SI contributes to about 60–80% of the total maltose digesting capacity in the intestine.
The role of MGAM in starch digestion is robustly established through biochemical, genetic, and clinical evidence. Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The synergistic relationship between MGAM and sucrase-isomaltase was illustrated in a 2023 study in Frontiers in Molecular Biosciences: it has been hypothesized that starch digestion can be modulated via "toggling" of activities of these mucosal alpha-glycosidases, suggesting a possible interaction between these two enzyme complexes in the intestinal brush border membrane.
Evidence strength: The core digestive function of MGAM is supported by decades of biochemical data, structural crystallography, and genetic studies. This is among the most firmly established functions in human nutritional biochemistry.
The mucosal maltase enzymes are characterized by an activity that produces glucose from linear glucose polymers, assayed with the disaccharide maltose. The related enzyme isomaltase produces glucose from branched glucose polymers. On one peptide, sucrase (maltase Ib) and isomaltase (maltase Ia) activities shared maltase activities but identified the enzymes as sucrase-isomaltase; on the other peptide, no distinguishing characteristics of the two maltase activities (maltases II and III) were detected and the activities identified as maltase-glucoamylase.
A notable human case study published in PMC (NIH) described a patient with a genetically confirmed loss of MGAM. The patient had a homozygous deletion within the gene encoding maltase-glucoamylase (MGAM), an intestinal starch digestion enzyme, predicting absence of enzyme activity and potential starch indigestion. The patient had a homozygous deletion within the gene encoding maltase-glucoamylase (MGAM), predicting absence of enzyme activity and potential starch indigestion. Validation testing using a functional MGAM analysis involved starch ingestion followed by measuring blood glucose and insulin levels as well as hydrogen breath levels. This clinical case, while a single-patient report, provides direct human evidence that MGAM loss impairs starch digestion.
In the context of congenital sucrase-isomaltase deficiency (CSID), CSID is an autosomal recessive disorder of carbohydrate maldigestion and malabsorption caused by mutations in the sucrase-isomaltase (SI) gene. SI, together with maltase-glucoamylase (MGAM), belongs to the enzyme family of disaccharidases required for breakdown of alpha-glycosidic linkages in the small intestine.
Evidence strength: Moderate to strong for genetic deficiency states. Clinical human data for MGAM-specific isolated deficiency are limited to individual case reports. Evidence for SI-related maltase reduction in CSID is more robust.
Maltase is most commonly used in supplement form as part of multi-enzyme blends. Evidence for multi-enzyme preparations (which typically include amylase, protease, lipase, and disaccharidases including maltase) in functional gastrointestinal complaints has been reviewed in the peer-reviewed literature.
In recent years, several well-designed clinical studies have shown that pancreatic or digestive enzyme supplements could be promising alternative approaches in managing functional dyspepsia (FD) syndrome. A few studies have suggested that therapy with multienzyme preparations is beneficial for reducing symptoms of flatulence, bloating, belching, fullness, and postprandial distress in patients with FD.
A randomized, double-blind, placebo-controlled study of a multienzyme complex including carbohydrase activity in patients with functional dyspepsia (published in Journal of Medicinal Food, 2018, PMC6249666) found that multi-enzyme supplementation was associated with symptom improvement compared to placebo; however, the specific contribution of maltase within the blend could not be isolated in that design.
A study published in PMC (2014, PMC4094108) comparing a digestive enzyme complex (Similase) against domperidone in patients with common GI complaints reported: significant improvements of all symptoms were seen following treatment with domperidone or Similase as evidenced by decreased scores. After five days of treatment, Similase was significantly better in reducing abdominal pain compared to domperidone (p=0.021). For the other gastrointestinal complaints, no significant differences were seen between domperidone and Similase.
An exploratory randomized, double-blind, placebo-controlled study published in PMC (2024, PMC11292951) examined an enzyme blend (Elevase®) in ileostomy patients and noted: molecules linked to the metabolism of complex carbohydrates such as amylose or maltose were not statistically significant between the groups. The reason for this could be the fact that amylose was broken down by the action of salivary and pancreatic amylases and Elevase® into glucose and maltose. Then, the presence of maltase in the small intestine would have further catabolized maltose to glucose.
Evidence strength: The evidence for multi-enzyme supplementation in functional dyspepsia is preliminary to moderate. No clinical trials have isolated maltase as a single active agent; all human studies to date involve combination enzyme formulas. Attributing specific outcomes to maltase alone is not currently possible based on available evidence.
One of the most scientifically significant and extensively researched aspects of maltase/MGAM relates not to its supplementation, but to its inhibition as a therapeutic strategy for managing postprandial hyperglycemia in type 2 diabetes.
MGAM has become an efficient drug target for insulin resistance. In order to explore the conformational changes in the active pocket and unbinding pathway for NtMGAM, molecular dynamics (MD) simulations and adaptive steered molecular dynamics (ASMD) simulations were performed between two inhibitors (DSK and acarbose) and NtMGAM.
Alpha-glucosidase inhibitors have been used to control postprandial glucose levels caused by type 2 diabetes since 1990. Maltase-glucoamylase (MGAM) belongs to glycoside hydrolase family 31. The main function of MGAM is to digest terminal starch products left after the enzymatic action of alpha-amylase; hence, MGAM becomes an efficient drug target for insulin resistance.
Acarbose and miglitol, which were clinically used for treating type 2 diabetes, may control blood glucose levels by targeting alpha-amylases and alpha-glucosidases. Structural studies using X-ray crystallography have elucidated how acarbose binds to the active site of MGAM. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. Crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å, have been reported.
These structural findings contribute to the advancement of functional foods and therapeutic interventions for postprandial hyperglycaemia and type 2 diabetes.
Research into novel, more selective MGAM inhibitors is ongoing. A virtual screening procedure was applied to identify new potential nt-MGAM inhibitors as a possible medication for type 2 diabetes. A series of salacinol analogues were investigated by docking analysis for their binding to the X-ray structure of the biological target nt-MGAM.
Evidence strength: The role of MGAM as a drug target for postprandial glycemia is well-established. Clinical evidence for approved alpha-glucosidase inhibitors (acarbose, miglitol) acting through this mechanism is strong. Research into novel MGAM-specific inhibitors is currently at the in-silico and preclinical stage.
The lysosomal form of maltase, acid alpha-glucosidase (GAA), has a well-characterized role in a rare but serious genetic disease. Pompe disease (also known as acid maltase deficiency or glycogen storage disease Type II) is a rare, autosomal recessive genetic disorder caused by the deficiency of lysosomal acid alpha-glucosidase (GAA), an enzyme that degrades glycogen.
The clinical presentation of Pompe's disease is variable with respect to the age of onset and rate of disease progression. Patients with onset of symptoms in early infancy (infantile-onset Pompe disease) typically exhibit rapidly progressive hypertrophic cardiomyopathy and marked muscle weakness. Most of them die within the first year of life from cardiac and/or respiratory failure. In the majority of cases, onset of symptoms occurs after infancy, ranging widely from the first to sixth decade of life (late-onset Pompe's disease). Progression of the disease is relentless and patients eventually progress to loss of ambulation and death due to respiratory failure.
Genzyme (a Sanofi company) developed alglucosidase alfa, which contains the active ingredient recombinant human acid alpha-glucosidase (rhGAA), as long-term enzyme replacement therapy (ERT) for patients with a confirmed diagnosis of Pompe disease. Alglucosidase alfa treatment is globally approved (tradenames: Myozyme® and Lumizyme®) for the treatment of Pompe disease based on its efficacy to prolong invasive ventilator-free survival in infants and its ability to improve walking distance and to stabilize respiratory function in children 8 years and older and adults.
Evidence strength: Strong clinical and regulatory evidence for enzyme replacement therapy in Pompe disease. This area involves a pharmaceutical drug (alglucosidase alfa), not an over-the-counter dietary supplement; it is included here for completeness of the maltase enzyme family's clinical relevance.
Several animal studies have investigated how modulation of intestinal maltase activity affects systemic glucose levels. In a rodent study (PMC3617660), the supplement of trigonelline to surviving diabetic rats significantly decreased intestinal alpha-amylase and maltase by 36 and 52%, respectively, which led to a significant decrease in the blood glucose rate by 46%. Diabetes induced a considerable increase in the alpha-amylase and maltase activities in the mucosal small intestine by 204 and 290% respectively, which led to an increase of the glucose rate by 236% in the serum of diabetic rats.
Evidence strength: This body of work is preclinical (animal model, in-vitro) only. Results from diabetic rodent models cannot be directly extrapolated to human supplementation outcomes.
Maltase in dietary supplements does not have a universally established or regulatory-approved dose. The FDA has not reviewed maltase-containing digestive enzyme products for safety or effectiveness. Supplement labels typically express maltase activity in enzyme activity units (e.g., Degrees of Diastatic Power [DU], or Alpha-Glucosidase Units [AGU]) rather than by mass, because enzymatic potency varies by source and preparation.
Such products are typically taken by mouth with meals and snacks. The dosage is based on the individual's medical condition, diet, and response to treatment.
In the multi-enzyme clinical study (PMC6249666), the evaluated multienzyme complex included amylase, protease, lipase, and cellulase at defined activity units; specific maltase activity amounts were not reported separately. In the in-vitro digestion study (PMC11066670), the digestive enzyme supplement (DigeSEB Super) contained amylase 20,000 SKBU/g, protease 13,000 PC/g, lipase 5 LU/g, cellulase 1000 CMC/g, lactase 1000 ALU/g, and hemicellulase 15,000 XU/g — again without separately specifying a maltase dose.
Alglucosidase alfa (Myozyme®/Lumizyme®), containing recombinant human acid alpha-glucosidase (rhGAA), is used as long-term enzyme replacement therapy (ERT) for patients with a confirmed diagnosis of Pompe disease. Specific intravenous dosing for this pharmaceutical agent is determined by clinical protocol and is outside the scope of a dietary supplement reference; it is not available over the counter.
Orally administered maltase, like other digestive enzymes delivered as dietary supplements, is generally considered to have a low adverse-event profile in the existing surveillance data. Canada Vigilance adverse event reports identified only 1 report for maltase/glucoamylase among a range of enzyme supplements, compared to 45 each for amylase and protease, 27 for lactase, and 41 for lipase. These data should be contrasted with the dearth of reported adverse events associated with such use of these enzymes.
If the capsule form of a maltase-containing digestive enzyme supplement is opened and the powder mixed with food or liquid, one should be careful not to inhale any of the powder, because doing so can irritate the inside of the nose or cause an asthma attack.
Since MGAM is the target of approved pharmaceutical alpha-glucosidase inhibitors used in type 2 diabetes management, there is a theoretically relevant interaction. Alpha-glucosidase inhibitors have been used to control postprandial glucose levels caused by type 2 diabetes since 1990. Acarbose and miglitol, which were clinically used for treating type 2 diabetes, may control blood glucose levels by targeting alpha-amylases and alpha-glucosidases. Supplemental exogenous maltase administered simultaneously with an MGAM-inhibiting drug (such as acarbose or miglitol) could theoretically interfere with the intended pharmacological effect of those medications; however, this interaction has not been directly studied in controlled clinical trials. The clinical relevance in this context warrants attention.
If the intestinal maltase capacity greatly exceeds the dietary maltose load on any given day, the maltase safety factor — defined as capacity divided by load — is high. The apparently high safety factor for maltase may be related to the multiple natural substrates hydrolysed by the multiple sites of maltase activity. This suggests that under normal dietary conditions, intestinal maltase capacity is not a limiting factor, and supplemental addition in healthy individuals with normal endogenous enzyme production may have minimal additional functional effect.
The FDA has not reviewed maltase-containing dietary supplement products for safety or effectiveness. No formal monograph for maltase as a dietary supplement has been established by the WHO, ESCOP, German Commission E, European Medicines Agency (EMA), or European Food Safety Authority (EFSA) that the available literature identifies. The NIH Office of Dietary Supplements DSLD lists maltase as an enzyme ingredient with the notation "Scientific Resources: N/A," indicating that no specific ODS-reviewed evidence summary is available for this ingredient.
Given that MGAM activity directly governs the rate of glucose release from dietary starch in the small intestine, supplemental maltase could, in principle, accelerate the conversion of maltose to glucose and therefore contribute to elevated postprandial blood glucose in predisposed individuals. This concern is theoretical and has not been quantified in controlled human trials. The preclinical rodent evidence does indicate a direct relationship between intestinal maltase activity and blood glucose levels: the inhibitory effects of alpha-amylase and maltase seem to have limited the process of carbohydrate hydrolysis and absorption in the intestine, which led to a decrease in serum glucose levels.
Maltase as a physiological enzyme is one of the most thoroughly characterized enzymes in human nutrition and gastroenterology. Its necessity for starch digestion, its molecular structure, and its relevance to both genetic disease (Pompe disease, CSID) and diabetes pharmacology (alpha-glucosidase inhibitors) are supported by strong, peer-reviewed, multi-decade evidence.
As a dietary supplement ingredient, however, the evidence base is substantially weaker. No large, well-powered randomized controlled trials have examined maltase as an isolated supplement ingredient in healthy or clinically defined populations. Human clinical evidence for maltase supplementation relates primarily to multi-enzyme combination products, making it impossible to attribute outcomes specifically to maltase. The NIH DSLD classifies the ingredient with no dedicated scientific resources, and no major pharmacopeial monograph governs its supplemental use. Claimed benefits for digestive comfort and energy support in healthy individuals with normal endogenous enzyme production remain unsubstantiated by direct human evidence.
Health conditions that Maltase may help support.
Maltase is a brush-border enzyme of the small intestine that converts maltose into two glucose molecules, completing starch digestion. Supplemental maltase is included in multi-enzyme digestive formulas to ensure complete carbohydrate breakdown and prevent fermentation of undigested maltose by colonic bacteria.
Body systems that Maltase may help support.
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