Carbohydrates are a basic component of human food. Along with proteins, lipids, vitamins and minerals, carbohydrates help humans maintain life, grow and develop.

1. What are carbohydrates?

Carbohydrates are a basic component of food that the human body uses to create energy. Carbohydrates include simple carbohydrates and complex carbohydrates.

Simple carbohydrates have a structure containing only one or two sugar molecules. Simple carbohydrates have one sugar molecule called monosaccharide (including fructose in fruits, galactose in milk, …); simple carbohydrates have two sugar molecules called disaccharide (including sucrose in sugar, lactose in dairy products, maltose in beer and some vegetables, …).

Complex carbohydrates have a structure containing three or more sugar molecules, called polysaccharides, which are the main components of starchy foods. Polysaccharides include two types: branched polysaccharides and unbranched polysaccharides. Complex carbohydrates are found in beans, peanuts, potatoes, corn, beets, cereals, whole grains, etc. Fiber is also a type of complex carbohydrate.

Natural sources of carbohydrates that people often use include:

• Fruits
• Vegetables
• Milk
• Nuts
• Cereals
• Spears
• Legumes

Carbohydrates are a basic component of food that the human body uses for energy.

2. Digestion and metabolism of carbohydrates in the body

Carbohydrates are the body’s main source of energy. Carbohydrate digestion begins with the activity of α – amylase in saliva (but not significantly), and mainly occurs in the upper part of the small intestine. At this stage, α – amylase will hydrolyze α – 1,4 glucoside into dextrin and maltose.

In the intestinal mucosal epithelial cells, there is also a similar enzyme, which then proceeds to hydrolyze the 1,6 glucoside bond and the 1,4 glucoside bond in the α – dextrin molecule to finally hydrolyze dextrin and maltose into glucose. The enzymes sucrase and lactase will hydrolyze sucrose and lactose into fructose, galactose and glucose.

The small intestine mucosa completes the active absorption of monosaccharides, in which glucose and galactose are selectively transported into the blood and transferred to the cells. Among the monosaccharides, hexoses are absorbed relatively quickly, while pentoses are absorbed relatively slowly.

The fastest absorbed hexoses are glucose and galactose, followed by fructose. If glucose is not needed by the body immediately, the conversion process into glycogen for storage will occur. Glycogen will be stored in the liver and skeletal muscles. If the glycogen reserves are full, the conversion process into lipids will occur. Thus, carbohydrates after being absorbed in the body will have three directions:

• Into the blood
• Stored as glycogen
• Converted into lipids

If the amount of stored or absorbed carbohydrates is not enough, the body will generate energy from protein (by breaking down proteins into amino acids and converting them into energy-producing substances), and thus, muscle mass will be affected, because protein is the building block of muscle.

One gram of carbohydrate provides approximately 4 kcal, equal to the amount of energy provided by one gram of protein, and one gram of lipid provides approximately 9 kcal.

According to the US nutritional recommendations, the body should receive 45 – 65% of total energy from carbohydrates, of which a maximum of 10% should come from simple carbohydrates. Thus, if the total daily energy intake is 2000 calories, the amount of energy provided by carbohydrates will be around 900 – 1300 calories, equivalent to the amount of carbohydrates consumed each day is 225 – 325 g.

The human body does not have the necessary enzymes to digest fiber, so fiber cannot be converted into energy. However, fiber is very necessary and beneficial for the digestive system. The amount of fiber adults need to eat each day is:

• Men 50 years and younger: 38g
• Men over 50 years: 30g
• Women 50 years and younger: 25g
• Women over 50 years: 21g

Fiber is essential and beneficial for the digestive system.

Information about carbohydrate content can be found on the label attached to the food package, in the Nutrition Facts section. The sections to look for are:

Total carbohydrates: This section identifies the total amount of carbohydrates in the product, including the amounts of ingredients such as sugars, fiber, and other carbohydrates.

• Dietary fiber: This section identifies the total amount of fiber in the product.
• Sugars: This section identifies the total amount of carbohydrates from sugars in the product, which can be natural sugars such as lactose and fructose or added sugars such as high fructose corn syrup.
• Other carbohydrates: This section identifies the total amount of digestible carbohydrates other than sugars.
• Sugar alcohols: Some product labels list sugar alcohols below the total carbohydrates section. For some people, sugar alcohols can cause digestive problems such as bloating, stomach pain, or diarrhea. If you are concerned about this ingredient, it will be listed under names such as lactitol, mannitol, maltitol, sorbitol, xylitol, etc. Many “sugar free” or “reduced calorie” products still contain some sugar alcohols, even though they have other sweeteners in the product such as Splenda.

3. Choose good sources of carbohydrates for your body

Carbohydrates are an essential part of a healthy, balanced diet. Carbohydrates provide many important nutrients, but not all carbohydrates are equally good. To have a healthy, balanced diet, consider the following when choosing carbohydrates:

• Focus on fresh vegetables and high-fiber fruits: Focus on whole fruits and vegetables that are fresh, frozen, or canned but have no added sugar. Other options are fruit juice and dried fruit, which are natural sources of sugar, and therefore provide more energy. Whole fruits and vegetables are rich in fiber, which helps the body feel fuller for longer while absorbing less energy.
• Choose whole grains: whole grains are better than refined grains, because they are rich in fiber and other important nutrients (such as B vitamins). After being refined, grains will no longer retain their original composition.
• Choose skimmed dairy products: dairy products are a valuable source of nutrients, and try to choose low-fat varieties to limit the amount of energy intake as well as the amount of saturated fat. Avoid products with added sugar.
• Eat foods from legumes: beans, peas, lentils are easy to find and valuable sources of nutrients. They are low in fat but rich in folate, potassium, iron and magnesium, along with fiber. Legumes are rich in protein and can be a substitute for animal protein sources.

Legumes are rich in protein and can be a substitute for animal protein sources.

Refined foods (white flour, white rice, etc.) are not as good as unrefined foods. And foods to avoid include foods and drinks with added sugar. Although they do provide energy, they are empty calories, and they provide little or no other nutrients.