The components of the food we eat: carbohydrates
Carbohydrates are organic compounds divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides and disaccharides are commonly referred to as sugars, while oligosaccharides and polysaccharides are complex carbohydrates and are often referred to as starch or starchy foods. Carbohydrates perform numerous functions in the human body and are an ideal source of energy, as they can be easily converted to glucose compared to fats and proteins. There are two types of carbohydrates, simple carbohydrates like sugars (found in sweets, honey, jams, and desserts) and complex carbohydrates like cereals, bread, rice, and pasta, etc.
SIMPLE CARBOHYDRATES
SUGARS: There are two types of sugar, (a) simple sugars, which include glucose, fructose, and galactose; and (b) complex sugars, consisting of at least two simple sugars, for example, sucrose, maltose, and lactose.
SIMPLE SUGARS
Glucose: Glucose, also known as dextrose, is found naturally in fruits, fruit juices, and the blood of live animals. Most of the carbohydrates in food are eventually converted to glucose in the body.
Glucose Syrups – Glucose syrups, also known as liquid glucose, are less sweet than glucose. They are used in many manufactured foods, including sugar, confectionery, soft drinks, and jams. Dried glucose is also made for domestic and industrial use.
Fructose: Fructose is found naturally in some fruits and especially in honey. It is the sweetest sugar known. It is also a component of sucrose, from which it can be derived.
Galactose: Galactose is produced primarily as part of lactose (milk sugar), but can be found in the free state in some foods.
SUGAR COMPLEX
Sucrose: Sucrose, known as table sugar, is found naturally in sugar cane and sugar beets and to a lesser extent in fruits and some root vegetables such as carrots and sweet potatoes. Chemically, it is a combination of two simple sugars (glucose and fructose).
Maltose: Maltose is formed during the breakdown of starch by digestive enzymes and when grains germinate for the production of malt liquors such as beer. It is a combination of two glucose units.
Lactose: Lactose is known as milk sugar and therefore is found (only) in milk, including breast milk. It is less sweet than sucrose or glucose and is a combination of glucose and galactose.
Although all sugars dissolve in water, they vary in sweetness. All provide readily available sources of energy. Glucose, galactose and fructose provide 3.75 kcal / g and sucrose, maltose and lactose provide 4 kcal / g. Sugars are used for various purposes in food preparation, for example, as preservatives in jams, marmalades, etc. and they also provide certain characteristics such as texture and consistency in cookies, cakes, soft drinks, etc. Although sugars and starch provide similar amounts of calories, they have different physiological effects on the human body. It should be noted that excessive consumption of these foods should be avoided due to serious health consequences. For example, eating large amounts of sugary foods at frequent intervals, especially between meals, is associated with an increased risk of cavities. Additionally, sugars are energy nutrients and should be consumed in moderation to avoid weight gain, especially if a reduction in energy intake is needed in order to lose or maintain weight.
Emphasis should also be placed on reducing visible and hidden sources of sugar, including cakes, cookies, ice cream, chocolate, candy, and carbonated beverages, not just sucrose / table sugar and fruit juices.
When a reduction in the fat content of the diet is desired, the best way to replace some of the lost energy is to increase the consumption of foods rich in fiber and starch, such as whole grains for breakfast, whole wheat pasta, wild rice. and cereals, including oats and millet.
The UK government has now set targets for the amount of sugar, starch and fiber that the population should consume on average. Sugars in fruit juices, sucrose and sugars added to food should not contribute more than 10% of the average dietary energy of the population. 40% of the energy in food should come from starch and other sugars, such as those found in milk and whole fruits and vegetables.
SWEETENERS WITHOUT SUGAR
Besides natural sugars, other substances also taste sweet. Unsweetened sweeteners include sorbitol, mannitol, and xylitol. They are also known as sugar alcohols and are sometimes used in diabetic products because they are absorbed slowly compared to sugar. However, diabetic products are no longer recommended for diabetes. The energy value of sugar-free sweeteners is similar to that of glucose, but for labeling purposes they are considered to provide 2.4 kcal / g. In contrast, saccharin, aspartame, and acesulfame-K are classified as food additives since they have no chemical or nutritional relationship with sugars. They are about 200-500 times sweeter than sucrose and are therefore used in very low concentrations, so that even aspartame, which is the only one metabolized by the body, does not essentially provide energy.
Some unsweetened sweeteners are frequently used as sweetening agents when caloric restriction is indicated, especially from sugar. Certain sweetening agents, which are available in granular form, are mixtures of an intense sweetener and a carbohydrate diluent and, as such, are sources of energy.
STARCH CARBOHYDRATES
Examples of starchy carbohydrates include cereal grains, bread and bread products, potatoes, flatbreads, pasta, rice, couscous, noodles, and breakfast cereals. Vegetables and legumes also contain starchy carbohydrates. These foods increase the concentration of glucose in the blood even though they do not taste sweet. The body digests them and breaks them down into glucose (sugar).
Examples include potato, sweet potato, pasta, rice, cracked wheat, couscous, polenta, cereals, grains, breakfast cereals, and oatmeal.
One gram of starch provides approximately 4.2 kcal of energy (similar to that provided by sugar), but a calorific value of 4 kcal is usually used for food labeling.
It should be noted that some forms of processing, for example the dry heat used in making certain breakfast cereals, can render some of the starch indigestible. This fraction, known as resistant starch, is considered fiber, along with NSP.
According to recent guidelines for healthy eating, complex carbohydrates or starchy foods should form the basis of energy in the diet and should provide the majority of dietary energy for humans. Therefore, it is recommended that carbohydrates contribute at least 50% of the total energy intake. This means that in a 2000 kcal diet, 1000 kcal must be provided by carbohydrates, which is equivalent to 240 g evenly distributed throughout the day, instead of being consumed in one or two meals.
However, until recently, sucrose and glucose syrups contributed 29% of total carbohydrate intake, 7% from lactose and the rest from starch. This is in contrast to what was the norm a century ago, when the consumption of flour and potatoes was much higher than that of sugars.
POLYSACCHARIDES WITHOUT STARCH (FIBER)
In addition to starch, there are other carbohydrates found in the cell walls of fruits, vegetables, legumes and cereal grains, where they provide structural support to the plant. This range of different compounds is classified as fiber or dietary fiber.
The fiber found in wheat, corn, and rice is primarily insoluble cellulose and related materials. But those found in fruits, vegetables, oats, barley, rye, beans, and legumes are soluble and include pectin and gum. Insoluble fiber fractions are not absorbed into the body, but they add bulk to the stool and thus help prevent constipation. This property is beneficial for health and plays a very important role in the prevention of many serious diseases, such as diverticulitis and colon cancer.
The soluble fiber in fruits like apples and oranges, vegetables, and legumes (beans and lentils) can be absorbed and can help lower blood cholesterol levels and increase high-density lipoprotein (HDL) cholesterol. More importantly, soluble fiber plays a key role in regulating blood sugar levels in people with diabetes.
Pectin is present in apples and many other fruits, as well as tubers like turnips and sweet potatoes. Pectin is not fibrous, and because it is completely digested, it has little effect on regulating bowel movement. However, pectin and other soluble fiber components can help lower blood cholesterol levels and blood glucose levels.
Since the effects of soluble and insoluble fiber are beneficial, it is recommended to include a variety of foods rich in fiber (NSP) in the diet. Daily fiber intake in the UK is around 12g / day on average, mainly provided by vegetables and grains. An increase in the average fiber intake to 18 g / day is currently recommended. In Therapia the contribution of all types of fiber is maximized by promoting the consumption of a variety of fruits and vegetables grown naturally, as well as a huge variety of vegetables and legumes, as well as cereals for breakfast.
However, there has been an increase in recent years (especially in the 1990s) in the consumption of whole wheat bread and breakfast cereals that contain bran, including soft cereal varieties. It is necessary to take into account that some components of the fiber, namely phytate, can bind to certain mineral metals such as calcium, copper, zinc and iron, thus they are not available for absorption. However, only those with low or marginal mineral intake are likely to be adversely affected by high fiber diets.