Alpha galactosidase is an enzyme that has several different functions. It is used by intestinal microorganisms to degrade the sugars in the complex carbohydrates found in vegetables and grains. This process often leads to the production of gases that can cause bloating and flatulence. This temporary condition may be treatable with dietary supplements containing alpha galactosidase. The absence of this enzyme can cause a genetic disorder known as Fabry’s disease.
Complex carbohydrates, like beans, broccoli, Brussels sprouts, and whole grains, are composed of many complex sugars. These sugars are present as polysaccharides, long chains of sugars, and oligosaccharides, shorter chains. They are degraded by various enzymes to smaller units. The end goal is for them to be degraded to monosaccharides — which are single molecules of sugars, such as glucose and galactose — that can be absorbed by intestinal cells and used as energy sources.
The sugars are joined in an alpha galactoside linkage. This is a relatively easy linkage to break chemically, but requires the action of alpha galactosidase adding a molecule of water. This enzyme has exo activity, it cleaves the terminal galactose unit and not within the molecule. The sugar is known as a glycoside, and this enzyme is referred to as a glycoside hydrolase enzyme. Unfortunately, since the human stomach and intestinal tract lack alpha galactosidase, compounds composed of two or three sugar molecules, like melobiose and raffinose, pass directly into the large intestine.
Once in the large intestine, these small polymers can be degraded to galactose and other sugars, such as glucose or sucrose, by the microorganisms that naturally live there. These microbes degrade the sugars anaerobically by fermentation, however, and produce a number of gases. They include methane, hydrogen, and carbon dioxide. This build-up of gases can lead to a feeling of bloatedness and gastrointestinal discomfort, along with increased flatulence.
There are a number of dietary supplements that include alpha galactosidase, and one can take these to help with this gas problem. The most prominent is Beano®. Such products facilitate the degradation of complex carbohydrates into simple sugars, making them more digestable. Studies sponsored by the manufacturer suggest that taking such products reduces the discomfort experienced by some people after eating these complex carbohydrates. Those with diabetes and a rare disorder affecting galactose should see a doctor before taking such supplements, as should pregnant women or those who are breast-feeding.
Although not involved in digestion, alpha galactosidase does have a physiological function in humans, and is encoded by the GLA gene. It hydrolyses the terminal galactose group from proteins and lipids with galactose on them. These molecules are involved in many different processes, from the functioning of nerve cells to being involved in the communication between cells.
There are a number of mutations in the GLA gene that can be inherited. This can result in a devastating disorder called Fabry’s disease, particularly among males. These patients do not produce alpha galactosidase and suffer from a variety of symptoms that can be hard to diagnose. There is an expensive treatment for this disorder, involving the use of alpha galactosidase produced recombinantly by the fungus Aspergillus niger. While not a cure, this has been able to ameliorate the symptoms of this serious disorder.