Introduction

               Carbohydrates are one of the most important nutrients required by the human body. They are the body’s primary source of energy and play a vital role in maintaining health and supporting daily activities. Every movement we make, from walking and running to thinking and breathing, requires energy. Most of this energy comes from carbohydrates present in our food.

               The term carbohydrate is derived from the words “carbon” and “hydrate,” indicating that these compounds are made up of carbon, hydrogen, and oxygen. Carbohydrates are found in a wide variety of foods such as rice, wheat, bread, potatoes, fruits, sugar, and cereals. Since they are readily available and economical, carbohydrates form a major part of the diet of people all over the world.

Definition of Carbohydrate

               Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen. They are the main energy-giving nutrients in our diet and provide energy for various bodily functions.

               Nutritionists often describe carbohydrates as the body’s fuel because they are broken down into glucose, which is used by cells to produce energy.

Importance of Carbohydrates

               Carbohydrates are essential for maintaining normal body functions. They provide the energy required for physical activities, growth, and development. The brain and nervous system mainly depend on glucose, a simple form of carbohydrate, for their energy needs.

               Carbohydrates also help spare proteins from being used as an energy source. This allows proteins to perform their primary functions of growth and tissue repair. In addition, carbohydrates assist in the proper metabolism of fats and help prevent the accumulation of harmful substances called ketones in the body.

               Many carbohydrate-rich foods, especially whole grains, fruits, and vegetables, are also good sources of dietary fiber, vitamins, and minerals. Thus, carbohydrates contribute to overall health and well-being.

Classification of Carbohydrates

Carbohydrates can be classified into three main groups based on their chemical structure and complexity.

1. Monosaccharides (Simple Sugars)

               Monosaccharides are the simplest form of carbohydrates and cannot be broken down into smaller carbohydrate units. They are easily absorbed by the body and provide quick energy.

The most common monosaccharides are:

Glucose

Glucose is the most important carbohydrate in the body. It is often referred to as blood sugar and serves as the primary source of energy for cells.

Fructose

Fructose is known as fruit sugar because it is naturally present in fruits, honey, and some vegetables. It is sweeter than glucose.

Galactose

Galactose is usually found combined with other sugars, especially in milk.

2. Disaccharides

               Disaccharides are formed when two monosaccharide molecules join together. They must be broken down into simpler sugars before the body can absorb them.

Common disaccharides include:

Sucrose

Sucrose is commonly known as table sugar. It is obtained from sugarcane and sugar beet.

Lactose

Lactose is called milk sugar and is present in milk and dairy products.

Maltose

Maltose is found in germinating grains and malted foods.

3. Polysaccharides

Polysaccharides are complex carbohydrates made up of many monosaccharide units joined together. They provide sustained energy and are generally digested more slowly.

Starch

Starch is the main storage carbohydrate in plants. Foods such as rice, wheat, potatoes, and corn are rich in starch.

Glycogen

Glycogen is the storage form of carbohydrate in animals and humans. It is stored mainly in the liver and muscles.

Cellulose

Cellulose forms the structural component of plant cell walls. Humans cannot digest cellulose, but it acts as dietary fiber and supports digestive health.

Sources of Carbohydrates

Carbohydrates are widely distributed in both plant and animal foods.

Plant Sources

Plants are the primary source of carbohydrates. Important plant sources include:

• Rice
• Wheat
• Maize
• Barley
• Oats
• Potatoes
• Sweet potatoes
• Fruits
• Sugarcane
• Honey
• Pulses and legumes

These foods supply a significant portion of the energy required by the body.

Animal Sources

Animal sources contain smaller amounts of carbohydrates. Examples include:

• Milk
• Yogurt
• Dairy products

The carbohydrate present in milk is lactose.

Digestion of Carbohydrates

               The digestion of carbohydrates begins in the mouth. Saliva contains an enzyme called salivary amylase, which starts breaking down starch into simpler sugars.

               After reaching the stomach, carbohydrate digestion temporarily slows because stomach acids inhibit the activity of salivary amylase. The process continues in the small intestine, where pancreatic amylase further breaks down carbohydrates into smaller units.

               Enzymes present in the intestinal wall convert these carbohydrates into simple sugars such as glucose, fructose, and galactose. These sugars are absorbed into the bloodstream and transported to various cells of the body where they are used to produce energy.

Functions of Carbohydrates

Carbohydrates perform several important functions in the body.

Energy Production

The primary function of carbohydrates is to provide energy. Each gram of carbohydrate supplies approximately 4 kilocalories of energy.

               This energy is required for physical activities, body functions, and maintaining body temperature.

Protein Sparing Action

               When adequate carbohydrates are available, proteins are used for growth and repair rather than being broken down for energy.

Fat Metabolism

               Carbohydrates help in the complete oxidation of fats. Adequate carbohydrate intake prevents ketosis, a condition caused by incomplete fat metabolism.

Storage of Energy

               Excess glucose is converted into glycogen and stored in the liver and muscles for future use.

Maintenance of Brain Function

               The brain relies heavily on glucose as its main source of energy. A continuous supply of glucose is necessary for proper mental functioning.

Dietary Fiber Function

               Certain carbohydrates such as cellulose provide dietary fiber, which helps maintain healthy digestion and prevents constipation.

Dietary Fiber

               Dietary fiber is the indigestible portion of plant foods. Although it does not provide energy, it plays an important role in maintaining digestive health.

               Fiber adds bulk to food, promotes regular bowel movements, and helps prevent constipation. It may also reduce the risk of certain diseases such as heart disease and diabetes.

Good sources of fiber include:

• Whole grains
• Fruits
• Vegetables
• Pulses
• Legumes

Recommended Intake of Carbohydrates

               Carbohydrates should contribute the largest share of daily energy intake. Nutrition experts generally recommend that 45–65% of total daily calories should come from carbohydrates.

               School-going children require adequate carbohydrate intake because they are actively growing and need energy for learning, sports, and daily activities.

               It is advisable to obtain carbohydrates mainly from whole grains, fruits, vegetables, and legumes rather than from sugary foods and beverages.

Deficiency of Carbohydrates

Insufficient carbohydrate intake can lead to various health problems.

A person may experience:

• Fatigue and weakness
• Reduced physical performance
• Dizziness
• Weight loss
• Difficulty concentrating
• Ketosis due to excessive fat breakdown

Children who do not receive enough carbohydrates may have reduced energy levels and impaired growth.

Excess Intake of Carbohydrates

Excessive consumption of carbohydrates, particularly refined sugars, can also be harmful.

Possible effects include:

• Weight gain and obesity
• Increased risk of dental caries (tooth decay)
• Elevated blood sugar levels
• Greater risk of type 2 diabetes
• Increased risk of cardiovascular diseases

Therefore, a balanced intake of carbohydrates is important.

Difference Between Simple and Complex Carbohydrates

               Simple carbohydrates consist of one or two sugar units and are digested quickly. They provide rapid energy but may cause sudden increases in blood sugar levels. Examples include sugar, honey, sweets, and soft drinks.

               Complex carbohydrates contain many sugar units linked together. They are digested more slowly and provide a steady release of energy. Examples include whole grains, cereals, pulses, and vegetables.

               For good health, complex carbohydrates should be preferred over simple carbohydrates.

Healthy Carbohydrate Choices

               A healthy diet should include nutrient-rich carbohydrate sources such as whole grains, fruits, vegetables, and legumes. These foods provide energy along with vitamins, minerals, and fiber.

Refined carbohydrates such as white sugar, candies, pastries, and sugary drinks should be consumed in moderation because they provide calories with limited nutritional value.

Typical Healthy Carbohydrate Sources

Examples of major carbohydrate sources in a balanced diet.

In Short

               Carbohydrates are essential nutrients and the body’s principal source of energy. They support growth, physical activity, brain function, and overall health. Carbohydrates are classified into monosaccharides, disaccharides, and polysaccharides, each serving different roles in the body. A balanced diet rich in whole grains, fruits, vegetables, and legumes ensures an adequate supply of healthy carbohydrates. While carbohydrate deficiency can cause weakness and poor health, excessive intake can lead to obesity and other health problems. Therefore, consuming the right amount and type of carbohydrates is vital for maintaining a healthy lifestyle.