Lactose, also known as milk sugar, is present in milk as well as milk products. This type of sugar is also found in human milk. This disaccharide does not naturally occur in any other food. This type of sugar is composed of carbon, oxygen and hydrogen and its chemical formula is C12H22O11. While children usually do not have any problem in digesting milk sugar, as they initially feed on breast milk, some adults, however, are not able to digest lactose and this medical condition is known as lactose intolerance.
In 1834, a French chemist named Jean Baptiste André Dumas named this type of sugar as lactose.
An Italian physician named Fabrizio Bartlett (1576-1630) is credited with discovering lactose and his finding was published after his death in 1633. Several years later, a Venetian pharmacist named Lodovico Testi published a booklet in 1700 comprising testimonials to show that milk sugar possesses the power to offer relief from various ailments, including the symptoms of arthritis. In 1715, an Italian medical scientist Antonio Vallisneri, also rendered as Antonio Vallisneri, published the procedure followed by Testi to produce milk sugar. In 1780, a Swedish Pomeranian Carl Wilhelm Scheele named lactose as sugar. In 1812, an evangelical theologian named Heinrich Vogel identified that hydrolyzing lactose could produce glucose. In 1856, Louis Pasteur crystallized galactose, a component of lactose. Later, by 1894, Emil Fisher established the different configurations of sugar components.
Infant mammals feed on their mother's milk, which contains rich amounts of lactose. They are able to digest lactose easily due to the presence of the enzyme lactase (β-D-galactosidase) secreted by the intestinal villi. Enzyme lactase helps to break down the lactose molecules into two simpler two sub-units - these are simple sugars called glucose and galactose. The baby's body can easily digest or absorb these simpler sugars. Since lactose is mostly found in the milk produced by mammals, its production decreases gradually as a person matures owing to continuous breast milk consumption.
Many people who have their ancestry in Europe, South Asia, West Asia, East Africa, West Africa and some regions of Central America continue their lactase production till they attain adulthood. This is because most people in these regions consume milk from different mammals like goats, cow and sheep in large quantities and it is one of their main food sources. This is the reason why the genes that help lactase production throughout one's life was first evolved in these regions. This aside, the evolution of genes of lactose tolerance in adults occurred independently among different ethnic groups. According to ancestry, over 70% people in Western Europe are able to consume milk even when they are adults. Compare this to the fact that below 30% adults hailing from Africa, Oceania and Eastern Asia and South Eastern Asia have lactose intolerance and are able to consume milk. The problem with people who suffer from lactose intolerance is that the milk sugar is not broken down into simpler sugars in their system. As a result, when they drink milk, lactose contributes to the development of gut flora that produces gas. This, in turn, can result in flatulence, bloating, diarrhea and several other gastrointestinal problems.
It is interesting to note that the amount of lactose present in milk can differ from one type of animal to another. Moreover, it can also vary depending on an individual animal or human. Generally, human milk contains a higher concentration of lactose - normally anything between 7% and 9% by weight, compared to the milk produced by other animals. For instance, milk produced by other mammals like cows, sheep and goats usually contain below 5% lactose by weight. Then again, in the case of nearly all processed milk, the percentage of lactose or milk sugar is inversely proportional to their fat content.
In other dairy products like butter, cheese, yogurt and margarine, milk sugar is present in varying degrees. Even the content of milk sugar in powdered milk and whey varies depending on many aspects. Butter, cheese and margarine contain very little quantity of milk sugar. On the other hand, powdered milk, condensed milk and whey contain a higher percentage of milk sugar - in some cases it is about 50% or even higher. Even the percentage of sugar found in yogurt can differ, but usually it is anything between 2% and 6%.
Lactose has a gentle flavour and is easy to handle. These two properties of the sugar milk have led people to utilize it in the form of a carrier as well as preservative for aromas. The same properties make it a useful component in pharmaceutical products.
Since lactose is less soluble compared to other sugars that generally are used in various foods, it is advisable not to add it directly all foods. In fact, it should never be added to infant formula directly. It is necessary to add lactose to infant formula because that helps to make the formula's composition similar to human milk.
One advantage of using lactose is that during brewing it does not ferment by most yeast. For instance, this advantage of lactose is utilized to make stout beer sweeter. The beer produced by sweetening stout beer with lactose is called a cream stout or milk stout.
Yeasts that are members of the Kluyveromyces have an exceptional industrial use. This is because this type of yeast can ferment lactose to produce ethanol. Moreover, the lactose leftover as a whey by-product during diary process has found to be a probable resource of alternative energy.
Lactose has several other uses too. One notable use of lactose is in the pharmaceutical industry where lactose is a vital ingredient in the manufacture of tablets and capsule drugs. It is added to these pharmaceutical products owing to its physical as well as functional properties. Lactose is not only cost effective, but also has compressibility. It is also used to dilute (water down) illicit drugs for the same properties.
This milk sugar is composed of two sugars and also forms the primary constituent in liquid whey. Most milk products also contain lactose. In addition, it is extremely vital for infants, especially during their development period. Additional advantages of consuming lactose are discussed below.
Very few people are aware of the fact that lactose is basically a type of carbohydrate – an essential nutrient for our body. Compared to sucrose, lactose is less sweet and, hence, it is generally used as a source of energy while preparing infants' food that require sweetening but not too much sugar.
Moreover, the glycemic index (GI) of lactose is significantly low and, therefore, it increases an individual's blood sugar levels gradually and very discreetly. Findings of different studies have revealed that people whose diets comprise foods having low GI actually age in a better way compared to those who consume foods having high GI.
It has been found that lactose consumption helps to enhance growth as well as development of a variety of bacteria in the intestines, such as Lactobacilli. Apart from this, this milk sugar also prevents the growth of specific pathogenic bacteria. Infants and children who consume foods rich in lactose content are able to resist stomach as well as intestinal infections more effectively compared to those who do not. Lactose is also beneficial in promoting good intestinal flora.
In addition, lactose is beneficial for us because it helps the body to absorb the essential minerals from the ingested foods and also facilitates the body in retaining these essential minerals. Our body needs vital minerals such as calcium, manganese, magnesium and zinc for our overall well-being as well as development. Consuming lactose ensures that our body properly absorbs all these minerals and uses them effectively too.
One good thing about lactose is that it is available easily. Many foods like milk, powdered milk and dairy products are good sources of lactose. Lactose also offers a pleasant taste and does not leave behind an aftertaste. As a result children also relish it and this milk sugar is very beneficial for them. Moreover, lactose is inexpensive and is present in dairy solids which are easily available. It also goes well with different ingredients.
Compared to other sugars, lactose is considered to be a low calorie and natural sweetener. It consists of natural sugar that is not harmful for our health. Despite being less sweet compared to granular sugar, lactose provides us with more energy. Moreover, compared to various other sugars, the metabolic effects of lactose is significantly less. Its glycemic index (GI) number is lower compared to glucose. Lactose is very useful for people suffering from diabetes and it also have very little effect on one's blood sugar levels. The lesser impact of lactose on blood sugar is an indication that it is not responsible for the various health problems caused by consumption of other types of sugars.
Often, lactose is added to prepared foods with a view to put off coating or caking. In fact, lactose is just about tasteless and, hence, it is makes the perfect filter in bread as well as other baked items, including cookies, pancakes and cereals. Generally, people also add lactose to frozen and canned vegetables with a view to prevent them from losing their original colors. In different countries and even different regions, this sugar is extracted from different types of milk. Most commonly, lactose is extracted from the milk of cows, sheep and goats. Of course, various other milk sources are also used for the purpose.
As discussed above, lactose is also beneficial because it promotes the growth and development of micro flora in the intestines, thereby helping to maintain a vigorous digestive tract. In the intestines, our body makes an enzyme called lactase that helps to break down lactose into simpler sugars to make it easily digestible. As people become mature, the ability of the body to produce lactase diminishes. In most adults, the body stops producing lactase and, as a result of this, all the lactose is not broken down into simpler sugars and it passes through the entire gastrointestinal tract. The good bacteria present in the digestive system take advantage of the undigested lactose and utilize the sugar as a source of energy for their growth and development. In this way, lactose facilitates the maintenance of a vigorous micro flora in the stomach.
Various ready-to-eat foods, especially powdered products, also contain some amount of milk sugar. Such foods include soups, dehydrated potatoes and even supplements that are taken as substitutes of meals. Food items with non-dairy labels may also enclose some milk sugar in the form of dry milk solids or whey. Even coffee creamers may contain some amount of milk sugars. In addition, they can also be present in candy, a variety of protein supplements, salad dressings and processed meats.