Galactose is a member of the simple milk sugar class. It enters the human body primarily as part of milk, is metabolized in the liver cells, and then enters the bloodstream. Cleavage is possible thanks to a special enzyme. In its absence, a violation occurs, called galactosemia. As a result of galactose oxidation, blood cells are formed in the body, complex carbohydrates are burned, metabolic processes are regulated.
What is galactose?
Galactose is a monosaccharide of the hexose class, which is a part of lactose disaccharide and other polysaccharides. It is not an essential nutrient. This white crystalline powder is slightly soluble in ethanol, and in water at 25 degrees Celsius. The melting point is about 165-170 degrees, caramelization of the substance begins at 160 Celsius.
It is found in milk, sugar beets, gums and in some energy drinks. There is a monosaccharide in the complex carbohydrates present in various fruits and vegetables, such as tomatoes, potatoes, celery, beets, kiwi, cherries. In addition, the human body is able to independently synthesize this substance, which is a compound of glycolipids and glycoproteins. Found in brain cells, nerve tissues.
This is one of three monosaccharides found in nature (the other two are glucose and fructose). It serves as a building block for another equally important carbohydrate – lactose, which a person receives from milk. This monosaccharide is essential for the production of milk in nursing mothers. But as a sweetener, galactose is used extremely rarely, although this substance belongs to sugars. Sweets in it are two-thirds less than in ordinary sugar. Meanwhile, given that galactose, like fructose, has a low glycemic index, it makes sense to talk about it as a safe sugar, in particular for people with diabetes. This substance is also used as a light sweetener in sports and other diet drinks.
Galactose, like glucose, belongs to the class of hexoses. Both monosaccharides are very similar in structure: they contain 6 carbon molecules, 6 oxygen and 12 hydrogen. But, despite the fact that all three monosaccharides (fructose, glucose, galactose) have the same formula – C6H12О6, there are still some biochemical differences. First of all, due to the different arrangement of atoms in each particular case, which makes these substances structural isomers.
It can exist in two different stereoisomeric forms:
D-isomer is a part of oligosaccharides, glycosides, polysaccharides. L-form, being a component of some polysaccharides, is found in red algae.
Sometimes galactose is called smart sugar, since a small amount of the substance can provide the body with a significant level of additional energy. Thanks to a structure different from other sugars, it is a useful substance for diabetics and people on a diet for weight loss.
In all mammals, galactose is synthesized in the body mainly from glucose. In chemical laboratories, scientists produce galactose from lactose – as a result of hydrolytic breakdown of the substance. After the oxidation of galactose, galactonic and galacturonic acids arise.
Characteristics of galactose:
- calories per 1 gram – 4;
- sweetness index – 0,3;
- glycemic index – 23.
Galactose metabolism through glycolysis requires a continuous supply of UDP-glucose (the active form of glucose). Galactose is metabolized from milk sugar, and as a result of several stages of glycolysis it is converted to glucose-1-phosphate.
Most of the monosaccharide absorbed by the body enters the liver, where it is converted to glucose, which is then used as an energy source or incorporated into glycogen. Compared with glucose, galactose is not able to significantly increase blood sugar.
Functions in the human body
In the human body, most of the galactose obtained from food is converted to glucose.
Galactose, combining with glucose, forms lactose (for breast milk). In combination with lipids, it creates glycolipids (including molecules that form A, B and AB blood groups). Galactose in combination with proteins serves as the basis for glycoproteins (important for cell membranes).
Role in the body:
- prevents diseases of the nervous system;
- regulates the functioning of the digestive organs;
- important for creating cell membranes;
- participates in the production of hemicellulose (to maintain cell structure);
- positively affects the functioning of the central nervous system;
- prevents the occurrence of Alzheimer’s disease;
- It is a component of lipids contained in connective tissue, brain, blood.
Perhaps one of the main advantages of galactose is its low glycemic index. Therefore, this simple sugar is useful for people involved in sports. In order to provide the body with energy during exercise, galactose is transformed into glucose and gradually raises blood sugar levels.
Usually the body metabolizes galactose in the liver without any problems. But in some individuals, the use of this monosaccharide can cause poor health. This disease is called galactosemia. Its cause is a genetic factor – the lack of an enzyme in the body that is responsible for the breakdown of galactose. In addition, non-perception of carbohydrate can also be through impaired liver function.
There are three types of illness. The first type is classical galactosemia, which occurs due to a lack of enzyme. Belongs to congenital pathologies and the first symptoms appear in the neonatal period (in infancy). The usual incidence of 1 to 40 is thousands of newborns. However, researchers say that representatives of certain nationalities are more prone to the onset of this disease. For example, in Ireland, the risk of congenital galactosemia is equal to 1 to 16 thousands of newborns.
Classical galactosemia is manifested by digestive disorders, a delay in the development of newborns. Sometimes this disease is mistaken for lactose intolerance. To determine which saccharide is the cause of the disease can only laboratory methods. If a baby suffering from galactosemia continues to consume lactose or galactose, he has liver dysfunction (eventually develops into cirrhosis), hypoglycemia, bilirubin rises, and the level of galactose in the blood rises. If this process is not stopped in time, a fatal outcome caused by liver failure, as well as damage to the brain or blindness, is possible. In addition, against the background of classical galactosemia, chronic complications may develop, including speech defects, cognitive impairment, infertility in women, caused by ovarian dysfunction.
The second type of galactosemia is a genetic disorder found in newborns with a frequency of 1: 10000. The symptomatology is very similar to the classic. The main difference is that it does not cause chronic complications. The third type of metabolic disorder of monosaccharide is accompanied by changes in the blood formula.
Today, traditional medicine cannot offer a cure for this disease. The only thing that doctors advise such patients is to avoid foods containing a high concentration of monosaccharide as much as possible.
In addition, people with intestinal disorders should be wary of galactose-containing foods. In enteropathy, for example, the mucosa of the small intestine is not able to absorb simple carbohydrates, such as galactose and glucose. As a result, severe diarrhea occurs, leading to dehydration, bloating. This disorder in most cases is congenital and is diagnosed in the first days of life. Less commonly, the disease develops with age.
The main source of food galactose is milk and yogurt lactose.
In addition, there is a small amount of free galactose in other milk foods, regardless of the presence of lactose in it. Including lactose-free milk, cheeses, sour cream, and ice cream can serve as a source of monosaccharide.
Dairy products containing monosaccharide: milk, kefir, whey, fermented baked milk, yogurt, yogurt, sour cream, ice cream, cottage cheese, cheese, cream, butter, margarine.
It was also found in fruits, vegetables (especially celery), nuts, grains, fresh meat, eggs. True, in this category of products the content of the substance usually does not exceed 0,3 g per serving. Also, carbohydrate reserves are in peas and milk chocolate. Well, a very small amount of galactose is found in some medicines.
To date, few use galactose. This is because most people are not even aware of the existence of this sugar. In the food industry, this simple carbohydrate is used to create a gum food supplement. Some athletes resort to this substance during training. But so far this sugar has not received wide distribution.
In medicine, galactose has found its application as a contrast medium for ultrasound diagnostics. Microbiologists use simple saccharide as a means of determining the type of microorganism.
Galactose consumed in excess, like any other sugar, can be harmful to the body. In particular, excessive use of galactose can cause tooth deterioration. Like lactose, it causes tooth decay. An overdose of monosaccharide can cause a mild laxative effect, which, however, is harmless, since the symptoms of diarrhea disappear with the removal of excess substances.
Galactose does not belong to irreplaceable substances. Meanwhile, scientists determined: for normal functioning of the body, it is necessary that the level of this substance in the blood be at least 5 mg per deciliter. It is easy to provide yourself with this norm if you consume galactose-rich foods (mainly dairy, containing lactose).
Particular attention to the list of these products should be paid to people in a state of stress and overwork, with increased mental and physical stress. Galactose should also be present in the diets of infants and nursing mothers.
For older people, people with intolerance or allergies to dairy food, as well as in the presence of intestinal diseases or inflammation of the female genital organs, it is better to refuse abundant consumption of galactose.
Excessive consumption of foods rich in this monosaccharide, especially in the presence of galactosemia, can adversely affect the condition of the liver, cells of the central nervous system, and the lens of the eye.
Symptoms of deficiency and overabundance
The body will tell about the lack of galactose by various symptoms. Of the most frequent – fast fatigue and distraction. People with a carbohydrate deficiency easily give in to depression, feel physical weakness.
Excessive consumption of galactose affects the nervous system and is manifested by hyperactivity. Other effects of galactose excess are serious liver and eye diseases.
Unlike other sugars, glucose is poorly soluble in water.
This monosaccharide is not suitable for cooking.
Cells of the brain and other organs need galactose to function.
It is part of milk without lactose.
Galactose is the substance that a person needs from the first days of life. And mother’s milk is the main source of carbohydrates for the baby. Although the need for this monosaccharide decreases over the years, it does not cease to be one of the most important components of a healthy diet.