Lactose Intolerance
Disaccharides are sugars that get formed when two simple sugars (monosaccharide) come together. Sucrose, maltose, and lactose are the most common disaccharides out there. You are already familiar with the latter one, that is, lactose. It is the primary element found in the milk of all mammals. In contrast with the majority of saccharides, lactose is not sweet. In simple words, lactose is a sugar that’s in milk. It gets used by the body for energy and numerous other functions. However, most people have difficulty in digesting lactose. In this article, you can learn about lactose intolerance, its symptoms, and the structure of lactose.
What is Lactose?
Lactose is a disaccharide containing two units, glucose and galactose. These units get bonded together by 1-4 glycosidic bonds in a beta orientation. Our bodies use an enzyme called lactase to digest the lactose, so it gets absorbed into the body. But, people not having adequate lactase in their body suffer from lactose intolerance.
Lactose Monohydrate
You can find lactose monohydrate mainly in milk and dairy products. It’s a naturally occurring disaccharide. You should know that lactose crystals have the water of crystallization due to which molecular mass becomes 360.3 g/mol as compared to 342.3 g/mol of anhydrous lactose. It is available in the white, crystalline powder.
Lactose monohydrate is soluble in water and slightly soluble in ethanol. Also, when the disaccharide gets heated to 418K temperature, it results in the loss of one of the molecules of water from lactose anhydrous. Below you can have a look at the structure of lactose monohydrate.
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Formation of Lactose Monohydrate
Lactose monohydrate is the crystalline form of lactose, and it’s the primary carbohydrate in cow’s milk. It gets composed of two simple sugars, galactose and glucose bonded together. It is found in two forms having different chemical structures – alpha and beta-lactose.
Lactose monohydrate gets produced when alpha-lactose from cow’s milk gets exposed to low temperatures until crystals begin to form. Further, the unwanted moisture gets dried off to render a dry, white or pale yellow powder.
It tastes slightly sweet and much similar to the milk. In simple words, lactose monohydrate gets produced by crystallizing lactose, the primary sugar in cow’s milk, into a dry powder.
Uses of Lactose Monohydrate
In food and pharmaceuticals, lactose monohydrate gets known as milk sugar. Since it has long shelf-life, sweet taste, great mix-ability, it has a great range of applications.
Mostly, it gets used as a food additive and filler for drug capsules. A major chunk of its application involves industrial use and not domestic.
Fillers such as lactose monohydrate get added to an active drug in a medication. So, it can render a pill or tablet, which is easy to swallow or consume.
As a matter of fact, 20% of prescription drugs and 65% of OTC drugs like calcium supplements, birth control pills, and acid reflux medications use lactose.
It also gets added in infant formulas, packaged snacks, and frozen meals. Further, processed cookies, cake, pastries, soups, sauces, and other food items contain the lactose too.
The main purpose of using lactose is to add sweetness or serve as a stabilizer so that ingredients don’t mess up.
Animal feeds have lactose monohydrates as it facilitates an affordable way to up the food volume and weight.
Lactose Intolerance
If your body cannot digest lactose, a sugar found in milk and other dairy goods, you have lactose intolerance. The condition occurs when the small intestine doesn’t produce adequate lactase, the enzyme that helps digest the lactose.
So, when your body is not producing enough lactase, the lactose you consume via dairy products doesn’t get digested. Instead, it gets treated or broken down by the bacteria in your colon, which further causes gas. It all can escalate quickly and show unpleasant symptoms.
Symptoms of lactose intolerance: These symptoms rely on the lactase production in your body. The typical symptoms of lactose intolerance include diarrhoea, vomiting, gas, gurgling, bloating, aches or cramps, etc.
FAQs on Lactose
1. What is lactose and what are its monosaccharide components?
Lactose is a type of sugar known as a disaccharide, naturally found in the milk of mammals. It is formed from two simpler sugar units, called monosaccharides. Specifically, a molecule of lactose is made up of one unit of β-D-galactose and one unit of β-D-glucose.
2. How are the glucose and galactose units joined together in lactose?
The two monosaccharide units in lactose are connected by a specific type of covalent bond called a glycosidic linkage. In lactose, this is a β-1,4 glycosidic linkage. This means the bond forms between carbon-1 (C1) of the galactose unit and carbon-4 (C4) of the glucose unit, with the galactose unit in its beta configuration.
3. Why is lactose classified as a reducing sugar?
Lactose is classified as a reducing sugar because the glucose unit in its structure possesses a free hemiacetal group. This group can open to form a free aldehyde group, which can be oxidised. This ability to be oxidised allows lactose to act as a reducing agent in chemical tests, such as with Benedict's or Tollens' reagent.
4. What are the main dietary sources of lactose?
Lactose is primarily found in milk and dairy products. Key sources include:
- Cow's milk, goat's milk, and human breast milk
- Cheese, especially soft cheeses like cottage and ricotta
- Yoghurt and kefir
- Butter and cream
- Ice cream and other dairy-based desserts
5. What is the chemical basis of lactose intolerance?
Lactose intolerance occurs when the small intestine does not produce enough of an enzyme called lactase. The function of lactase is to hydrolyse (break down) lactose into its simpler components, glucose and galactose, which can then be absorbed into the bloodstream. Without sufficient lactase, undigested lactose passes into the colon, where it is fermented by gut bacteria. This fermentation produces gases (like hydrogen, carbon dioxide, and methane), leading to symptoms like bloating, gas, and diarrhoea.
6. What are some important industrial applications of lactose?
Beyond being a nutrient in dairy, lactose has several important industrial applications. It is widely used in the pharmaceutical industry as a filler or excipient in tablets and capsules because it is inert, has a mild taste, and compresses well. In the food industry, it serves as a stabiliser, contributes to browning (the Maillard reaction) in baked goods, and adds texture to processed foods and infant formulas.
7. What is the difference between lactose and lactose monohydrate?
The primary difference lies in the presence of water within the crystal structure. Lactose (C₁₂H₂₂O₁₁) refers to the disaccharide molecule itself. Lactose monohydrate (C₁₂H₂₂O₁₁·H₂O) is the crystalline form of lactose that has incorporated one molecule of water (known as water of crystallisation) for every molecule of lactose. This monohydrate form is the stable state of lactose at room temperature and is the form commonly used in food and pharmaceutical products.
8. How is it possible for someone to develop lactose intolerance later in life?
Developing lactose intolerance in adulthood is a common genetic trait known as primary lactose intolerance or lactase non-persistence. For most mammals, including a majority of humans, the gene that produces the lactase enzyme naturally becomes less active after infancy. This is a biologically programmed decline, as the dietary dependence on milk typically ends after weaning. It is not an allergy but a reduced capacity to digest lactose that becomes more apparent over time.
