Galactose is special type of sugar that appears to provide a massive amount of energy from even a small quantity. At the same time, it has very good nutritional qualities. Because of this double benefit, it is sometimes classified as a nutritive sweetener. Galactan is a polymer of galactose and has been particularly targeted by modern research.
Chemically, galactose is part of the monosaccharides group. In order to produce disaccharide lactose, it has to be combined with glucose, the result being a reaction based on condensation. Two enzymes, lactase and β-galactosidase, act like a catalyst to the hydrolysis reaction between galactose and glucose. One of these enzymes is generated by the lac operon in the Escherichia coli bacteria.
Milk and every product based on milk are the most important natural sources of lactose. Since dairy products are an ingredient in numerous food items, lactose is now found in a wide range of products, including bread or cereals.
The Leloir pathway is the scientific name for the process of galactose metabolism that converts it to glucose with the help of three different enzymes. The three enzymes ordered by the stages of the pathway are: galactokinase (GALK), galactose-1-phosphate uridyltransferase (GALT), and UDP-galactose-4'-epimerase (GALE).
Human females also produce galactose when lactating. In human metabolism, our body uses hexoneogenesis to transform glucose into galactose, which allows the breast glands to secrete lactose. Lactose in human milk actually comes from several sources. Most of it is produced from blood galactose but some of it is synthesized through the process described above, while glycerol can also be a source for galactose production.
Industrially, galactose is also produced through a process of hydrolysis, by using hemicellulose as a raw material because of its richness in natural precursors. It has the same taste as sugar but it is much sweeter and a lower quantity is needed to get the same result. Another advantage is the much longer term of viability. However, it has the major drawback of being insoluble in liquids, which greatly limits its use and makes it rarely available in shops. For this reason, it can't actually replace sugar in many recipes and dishes, especially home-made ones. It can still be used as an ingredient in industrial produced food. Commercially, it is not only used as a sweetener because it has several other valuable properties: it balances the acidic and tart ingredients in food in order to give them an acceptable taste.
Our bodies also synthesize galactose naturally, as part of our metabolism. In lactation, this mostly happens through the production of galactose from glucose. This is important during the nursing process, because it stimulates secretion and enables the mammary glands to produce lactose. Another usage for galactose inside the body is as part of some tissues, where it can be found as glycolipids and glycoproteins.
Besides being produced in the human body, galactose is a natural product that can be found in numerous combinations in food items. One of the richest natural sources of galactose is sugar beets, this compound being responsible for their sweet taste. Another great source for galactose are dairy products of any type. It is added to gum, since it can make it sweet very easy, without the need of dangerous and expensive additives. Mucilages also have an important content of this compound. Macro-algae release galactose as a by-product of the third-generation production process of ethanol.
Galactose can easily be produced by the body from glucose and the other way around, when more energy is needed. However, in order to have a proper epimerase equilibrium mediated by enzymes, it is still quite helpful to have a source of galactose included in your diet. Significant test results have been reported from people who suffer from metabolic diseases. When these were treated with diets featuring low amounts of protein and lactose, sizeable amounts of galactose have been detected in both their red and their white cells.
Perhaps the most promising feature of galactose is that it doesn't increase the secretion of insulin when consumed. This could make it an alternative sweetener for diabetics, since it has no influence on serum galactose levels.
Other studies as well as clinical reports suggest that galactose can counter a wide range of problems, it reduces inflammation, speeds up the healing of wounds, increases the absorption and assimilation of calcium and can even prevent eye cataract.
While the exact mechanism is not understood yet, people with arthritis (both youngsters and adults) and lupus have low levels of galactose. This could mean that an increase intake of this compound might potentially cure these diseases.
The role of galactose as an antioxidant is not fully researched. However, animal tests have concluded that it can limit the development of tumours and the metastasis. People with colon cancer have decreased levels of galactose in their intestinal mucus, which suggests that more galactose in their food could stop the disease or even cure it completely.
At the same time, galactose is present in most of the important body internal organs. It seems to play a key role in the brain, being a catalyst of long-term memory storage. It must be critical to the kidney functions as well, since it was detected in both the proximal and distal tubules. Perhaps it also provides health benefits to the heart because it is a part of the intestinal mucus that limits the absorption of cholesterol and its build-up in the blood stream.
Along with other sugars, it has a high concentration in male testicles. This proves the saccharide is a key compound in human reproduction and it could be a component in the production of sperm.
Scientists have noticed that people with rheumatoid arthritis have a severely reduced level of galactose in the blood. Actually, the most severe cases of the disease also have the lowest level of this sugar in their blood stream. During times when arthritis is in remission, the galactose levels also increase back to normal, while moments when galactose was low seemed to trigger a critical metabolic failure, reducing the quantity of other important sugar types. This suggests that galactose is a very important component of our immune system, since it is also found in the composition of blood white cells and immunoglobulins.
Numerous other diseases, especially chronic and very severe ones, have been associated with low levels of galactose. For some reason, epithelial cells in the upper airways show the most catastrophic drop in the levels of this essential sugar. The consequence is that people become more vulnerable to breathing infections from bacteria and other pathogens, which can cause pneumonia or bronchitis.
Galactose is also important in the digestive system, especially because it keeps the intestinal bacteria at a healthy level. This provides two benefits at the same time: it improves digestion and strengthens the response of our immune system. Eating increased amounts of galactose boosts the numbers of bifidobacteria in particular but all of the symbiotic bacteria living in the human gut benefit from it.
A very exciting potential use for galactose is in the research of the currently incurable multiple sclerosis. Some scientists believe this horrible lethal disease can be directly linked to galactose deficiency. It is already known there is a connection between multiple sclerosis and the lack of xylose, which is another essential sugar, modern research now focuses on galactose as well. Multiple sclerosis develops when our own white cells start attacking the myelin layer that covers the nerves, damaging them beyond repair. Since this layer is rich in galactose and other bioactive sugars, increasing their levels might allow the body to repair the nerves and reverse the disease.
