12 Concept of Balanced Diet

Ms. Sukhmani Kaur and Dr. Meenal Dhall

Contents:

1. An introduction

2. Balanced diet

2.1 Definitions

2.2 Importance of balanced diet

2.3 Goals of balanced diet

2.4 Components of balanced diet

3. Carbohydrates

3.1 Classifications of carbohydrates

3.2 Sources of carbohydrates

3.3 functions of carbohydrates

3.4 daily requirements of carbohydrates

3.5 disease condition

4. Proteins

4.1 classifications of proteins

4.2 sources of  proteins

4.3 functions of proteins

4.4 daily requirements of proteins

4.5 disease condition

5. Fats

5.1 classifications of fats

5.2 sources of fats

5.3 functions of fats

5.4 daily requirements of fats

5.5 disease condition

6. Vitamins

6.1 classification of vitamins

6.2 sources of vitamins

6.3 functions of vitamins

7. Minerals

7.1 distribution of minerals in the body

7.2 sources of minerals

7.3 funtions of minerals

8. Water

8.1 distribution of water

8.2 functions of water in the body

8.3 daily requirement of water

8.4 disease condition

9. Summary

LEARNING OBJECTIVES:

• To understand the meaning of a good health.
• To know different types of food groups.
• To understand the concept of balanced diet.
• To find out the importance of a balanced diet.
• To explore the goals of a balanced diet.
• To discuss the components of balanced diet.

1. AN INTRODUCTION:

Food is the very basis of our life. The food we eat, through the process of digestion, is converted into nutrients, and these nutrients are absorbed, transported to different parts of the body, and utilized for the day-to -day functioning, at the end of which they are disposed off by further metabolism and transformation into the end products. We all need to consume a variety of foods in order to remain healthy. Foods are classified into different food groups. The basic five food groups concept is useful in getting a balanced diet that helps us to remain healthy. The basic five food groups are:

1) Cereal grains and products

2) Pulses and Legumes

3) Milk and Meat products

4) Vegetables and Fruits

5) Fats and Sugar

The five food group plan permits an individual to plan a menu to achieve nutrient intakes as specified by RDA.

The five food groups and their main nutrients suggested by ICMR are given in Table 1.1

An easy way to understand the balanced consumption of these five food groups is represented as four steps to a healthy diet as shown in Figure 1.1. Our daily diets for maintaining good health should be made up of generous amounts of vegetables and fruits, adequate amounts of cereals, pulses, milk and milk products, moderate amounts of meat and flesh foods and limited quantities of fats and oils, nuts and oil seeds and sugars as shown in the Figure below.

Figure: Four steps to a healthy diet

Now with this basic understanding, let us get to know what we mean by a good health. Can good health, also be referred to as positive health? Does it merely mean freedom from diseases or is it more than that? Let us see.

What constitutes good health?

Good health has been defined as a “state of complete physical, mental, and social well being and not merely the absence of disease or infirmity” (World Health Organization). The requirements for good health are many and these are outlined below.

To maintain good health, it is essential that we combine and consume a variety of foods in such a way that the nutrient needs for the above functions are all provided. Good nutrition thus provides all essential nutrients in correct balance which are further utilized to promote the highest level of physical and mental health. Such a state of nutrition can be attained through balanced diets. So, let us now understand the concept of balanced diet.

2. BALANCED DIET:

2.1 What is Balanced Diet? – A definition

Balanced diet can be defined as one which contains different types of foods (from all food groups) in such quantities and proportions that the need for calories, minerals, vitamins, proteins, and other nutrients is adequately met and a small extra allowance is made as a margin of safety. It can also be defined as a diet, which provides all the nutrients in the amount and proportion required to one’s age, sex and activity. Balanced diet not only meets our day-to-day nutrient requirements but also provides for an extra allowance of the nutrients to be stored in our body, which can be used in conditions of stress.

2.2 Importance of a Balanced diet

Thus, balanced diet enhances quality of life.

2.3 Goals of a Balanced Diet

• A balanced diet should provide around 50-60% of total calories from carbohydrate, 10-15% from protein and 20-30% of total calories from fat.
• Calorie allowance can be +50, while for all other nutrients minimum RDA must be met.
• Energy from cereals should not be more than 75 percent.
• Include two cereals in one meal; for e.g. rice and wheat.
• Two to three servings of pulses should be taken a day.
• To improve protein quality, the ratio of cereal protein to pulse protein should be 4:1.
• Include at least one medium size fruit. The fruit can be given raw without much cooking.
• Five servings of fruits and vegetables should be included in a day.
• Foods rich in fibre should be included.
• The diet should include minimum 100ml milk per day.
• One third of the nutritional requirements, at least calorie and protein should be met by lunch or dinner.

2.4 Components of a Balanced Diet

A balanced diet must provide the building blocks for growth and repair, and sufficient energy. The components of a balanced diet are:

• 1) Carbohydrates- the majority of energy intake should come from these molecules, which provide an energy source.
• 2) Proteins- needed for growth and repair, and are minor energy source.
• 3) Fats- major energy source, used for insulation and cell membranes, hormones and cholesterol.
• 4) Vitamins- these play an important role in the chemical processes taking place inside cells; some vitamins are water-soluble and some are fat-soluble.
• 5) Minerals- these are the inorganic elements occurring in the body that are essential for its normal functions.
• 6) Water- an important transport medium. Water is essential for the body to function, and it is involved directly in some metabolic reactions.

Now, let us understand these six components in detail.

3. CARBOHYDRATES:

Carbohydrates are simple sugar, which consists of hydrogen, oxygen and carbon. Main sources of energy are provided through the carbohydrates.

3.1 Classification of Carbohydrates

1. Monosaccharides

• Monosaccharides are simple form of carbohydrates. Monosaccharides of hexose’s group are glucose or dextrose, fructose or levulose and galactose.
• Glucose: Glucose is an aldose sugar, it is also known as grape sugar. Glucose is present in fruits and honey.
• Glucose is readily absorbed from the stomach.
• Fructose: Fructose is known as fruit sugar or levulose. It is the sweetest of all sugars, and it is sweeter than glucose. Honey is a rich source of fructose.
• Galactose: On hydrolysis of lactose, galactose is formed. It is not found free in nature. It is present in milk, sugar (lactose).

2. Disaccharides

Disaccharides are the complex sugar. Important disaccharides are sucrose, maltose and lactose.

• Sucrose: Sucrose is present in sugarcane, beetroot, honey, fruits and vegetables. Sucrose is easily hydrolyzed to glucose and fructose by diluted mineral acids or by enzyme sucrase present in intestinal juice.
• Maltose: Maltose is also known as malt sugar. It is present in sprouted grains and cereal grains. Maltose is formed when starch present in the food is digested by salivary and pancreatic amylase. It is hydrolysed to glucose by the enzyme maltase.
• Lactose: Lactose is also known as milk sugar. It is produced in the mammary gland. It is hydrolysed to glucose and galactose by the enzyme lactase present in intestinal juice.

3. Polysaccharides

• Common polysaccharides are starch, dextrin, glycogen, pectin and cellulose.
• Starch: Starch is present in cereal grains, seeds, root vegetables like potato, etc.
• Dextrin: Starch is broken down to dextrin, and dextrin is broken down to maltose.
• Glycogen: Glycogen is stored in the body in liver and muscles of animals. There are two types of glycogen-amylose and amylopectin.
• Indigestible Polysaccharides (or Dietary fibres)
• Indigestible Polysaccharides are cellulose, hemicelluloses, pectin and gum.
• Pectin: Pectin is used in the preparation of jam and jelly. Addition of pectin improves taste.
• Cellulose: Cellulose does not have any food value. It provides bulk to the diet and helps in movements in the large intestine. It prevents constipation. It helps in decreasing cholesterol level in the blood and reducing weight. It is present in bran, legumes, peas, vegetables of cabbage family, outer covering of seeds, apples.

3.2 Sources of Carbohydrates

There are three main sources of carbohydrates.

• Starch– Starch is present in cereals, roots and tubers.
• Sugars- Sugars are present in monosaccharides such as glucose, fructose and galactose and disaccharides such as sucrose, lactose and maltose.
• Cellulose- Cellulose is present in fruits, cereals and vegetables.

3.3 Functions of Carbohydrates

• Carbohydrates supply energy. One gram of carbohydrates gives four calories.
• Carbohydrates remove poisonous substances from the liver.
• Carbohydrate is used for synthesis of non-essential amino acids.
• Carbohydrate provides taste and flavor to the diet.
• Carbohydrate helps in formation of nucleic acid and matrix of connective tissues.
• Carbohydrates help in retention of water in the colon.

3.4 Daily Requirement of Carbohydrates

Indian diet mainly consists of carbohydrates mainly in the form of chapatis or phulkas, bread, potatoes, milk, sugar, etc. About fifty to sixty percent of diet is made up from carbohydrates. Daily diet consists of 300-500 gm of carbohydrates.

3.5 Disease Condition

Disease conditions caused due to excess consumption of carbohydrates are obesity and diabetes. Excess intake of carbohydrate in the form of sweet may lead to irritation of gastro intestinal mucosa and increases formation of gas. 

4. PROTEINS:

Proteins are complex organic nitrogenous compounds. These are the “building blocks of life” and are necessary for good health. It is very essential for the development of brain. Deficiency of protein causes mental retardation and growth retardation. The quality of protein depends upon the presence of number of amino acids.

Figure: Food containing Proteins

4.1 Classification of Proteins

Proteins are classified based on the chemical nature of amino acids, as simple, conjugated and derived proteins.

Let us get to know each of these.

1) Simple Proteins

Simple proteins are those which contain only amino acids or their derivatives and no prosthetic group. They yield only amino acids or their derivatives on hydrolysis. Let us see which are these and where are they found.

Albumins: They are readily soluble in water, dilute acids and alkalies. Serum albumin and egg white are examples. Seed proteins contain albumin in lesser quantities.

Globulins: They are insoluble or sparingly soluble in water, but their solubility is greatly increased by the addition of neutral salts such as sodium chloride. Serum globulin, myosin of muscle and globulins of pulses are examples. It is also found in haemoglobin, potatoes and in groundnuts.

Glutelins: They are insoluble in water and absolute alcohol but soluble in dilute alkalies and acids. They are plant proteins. Glutenin of wheat is a good example.

2) Conjugated Proteins

Conjugated proteins contain some non-protein substances (known as prosthetic groups). Some of the examples of conjugated proteins are glycoproteins, lipoproteins and nucleoproteins.

3) Derived proteins

These are proteins derived by partial to complete hydrolysis from the simple or conjugated proteins by the action of acids, alkalies or enzymes. These are either primary or secondary protein derivatives.

a) Primary Protein Derivatives:

These protein derivatives are formed by processes causing only slight changes in the protein molecule and its properties. Examples includes casein (curdled milk), fibrin (coagulated fibrinogen), cooked egg albumin.

b) Secondary Protein Derivatives

These proteins are formed in the progressive hydrolytic cleavage of the peptide bonds of protein molecule. Examples include proteoses, peptones and peptides.

Essential Amino Acids

The quality of protein depends upon the kind and amount of amino acid present in the food in relation to body’s need. Human body requires 22 amino acids. Out of these, eight are essential amino acids and rest are non-essential amino acids. Essential amino acids are those which our body cannot synthesized in sufficient quantity. These are supplied through the food we eat. These are valine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine and tryptophan. Histidine is also required for infants.

4.2 Sources of Proteins

The important sources of proteins are cereals, legumes, fish, eggs, milk and meat. Oilseeds, oilseed meals and soy are rich potential sources of proteins.

Table: Protein content of some important foods

4.3 Functions of Proteins

• Growth and Development: The primary functions of proteins is tissue growth and maintenance. The growth and development of the muscles, tissues, bones, cartilages, hair, nails, endocrine glands, teeth, skin, organs and body fluids all depend upon proteins.
• Source of Energy: Proteins contribute to the body’s energy need. One gram protein yields 4 Kcal.
• Proteins as Enzymes: Catalysts are needed to enhance each of the many reactions occurring in the cells. These catalysts called ‘enzymes’ are proteins.
• Binding factors: Proteins act as binding factors. Lipoproteins, transferring and serum protein helps in transporting chemical.
• Regulatory Function: Proteins regulate osmotic pressures and water balance within the body. Proteins functions as buffers and maintains pH. Contractile proteins regulate muscle contraction.

4.4 Daily Requirements of Proteins

Daily requirement of protein is one gram of protein per kilogram of body weight. During infancy and childhood protein requirement is more. In pregnancy protein requirement is increased by another 15-20 gram per day. Its requirement depends upon the size of the body, quality of protein consumed by an individual, previous health status of nursing mothers, efficiency of digestion and special physiological needs during illness, growth, pregnancy and lactation.

4.5 Disease Condition

Protein Deficiency

Deficiency of proteins causes mental retardation, Kwashiorkar and marasmus during infancy and childhood. During pregnancy, its deficiency causes abortion, still-births, premature births and anaemia. In adults it causes underweight, anaemia, weakness, delayed wound healing and increases susceptibility to infection.

Symptoms of Kwashiorkor: growth failure, moon-face, mental changes, oedema, muscle wasting, anaemia, liver changes, etc.

Symptoms of Marasmus: Growth retardation, wasting of muscle and subcutaneous fat, eye lesions, dry skin, etc.

5. FATS:

Fats are also known as lipids. These are organic compounds composed of carbon, hydrogen and oxygen. Smaller unit of fats is called as fatty acids. They are essential in diets to facilitate high-energy intakes and absorption of fat-soluble vitamins and provide essential fatty acids.

Figure: Food containing Fats

5.1 Classification of Fats

Fats are classified as:

1) Simple Fats

Simple fats are esters of glycerol and fatty acids. They are called triacylglycerols or triglycerides (for e.g. fats and oils) or higher alcohols (for e.g. waxes). Triglycerides are the major form of lipids present in human dietaries. They are major sources of fatty acids to the body.

2) Compound Fats

Compound fats are simple fats which combine with proteins (lipoproteins), carbohydrates (glycolipids), phosphates (phospholipids) etc. They are found in liver, egg yolk, brain cells and heart.

3) Derived Fats

Derived fats refer to fatty acids, cholesterol, glycerol and other derived compounds including fat-soluble vitamins, hormones and bile. Examples of derived fats are stearic acid, butyric acid, etc.

5.2 Sources of Fats

Fats are available in both plant sources and animal sources. The diet containing nuts, soy beans, oil seeds, avocado (butter fruit) and animal food contains higher amount of invisible fat.

Animal sources of fats are meat, butter, fish liver oil, cream. While the plant sources of fats are coconut oil, ground nut oil, mustard oil.

5.3 Functions of Fats

• Fat gives concentrated energy. One gram of fat gives nine calories of energy.
• Fats are the carriers of fats soluble vitamins A, D, E and K.
• The fat layer below the skin plays an important role in maintaining body temperature.
• Fats reduce gastric motility and remains in the stomach for a long time. It delays hunger.
• Fat provides support to many organs in the body such as heart, kidney and intestine.

5.4 Daily requirement of Fat

Normal person requires 50 to 60 gram of fat. A daily intake of 2400 Kcal Indian diet contains 40 g of fat where 25 g is invisible and 15 g is visible fat.

5.5 Disease Condition

Deficiency of Fat

Deficiency of essential fatty acids causes phrynoderma. It causes rough skin. Vitamin A, D, E and K deficiency occurs when fat is deficient in the body.

Excess Fat

Excess fat in the body causes obesity, high cholesterol level and heart diseases.

6. VITAMINS

Vitamins are defined as organic compounds, which are required for good health and vitality. It is required for the normal growth of the human body. They are required in very small quantity. These are found in fresh fruits and vegetables. Deficiency of vitamin causes structural and functional disorders of various organs.

Figure: Food containing Vitamins

6.1 Classification of Vitamins

Vitamins can be classified into the following two categories:

1) Fat-soluble Vitamins

These include Vitamins A, D, E and K. They can dissolve in fats and are absorbed with the help of fats that are in the diet. Excessive fat soluble vitamins are stored in the liver and will not be eliminated from the body.

2) Water-soluble vitamins

These include Vitamins B (vitamin B complex) and C. They can dissolve in water. Excessive amount of water-soluble vitamins are excreted through urine and sweat.

6.2 Sources of Vitamins

The major sources of vitamins are fresh fruits and vegetables. Other sources include wheat, legumes, oil seeds, nuts, meat, fish, milk, eggs, etc.

6.3 Functions of Vitamins

• Regulate metabolism.
• Help to convert energy in fat, carbohydrate, and protein into ATP.
• Promote growth and reproduction.

7. MINERALS:

Minerals are inorganic substances. For good health minerals are very essential. They form four percent of body weight. The functions of vital organs depends upon the presence of minerals. Names of the minerals are calcium, iron, magnesium, copper, iodine, potassium, cobalt, zinc, bromine, fluorine, arsenic, nickel, etc.

Figure: Food containing different Minerals

7.1 Distribution of Minerals in the Body

Calcium         2%

Phosphorus  1%

Others             1% (Magnesium, iron, zinc, iodine, copper, chromium)

7.2 Sources of Minerals

Different types of minerals are found in different types of food sources which include milk, milk products, peas, beans, potatoes, pulses, fish, green leafy-vegetables, eggs, nuts, oil seeds, dried-fruits, meat, cocoa, fruits, legumes, cereals, etc.

7.3 Functions of Minerals

• Minerals are required for the maintenance of body fluids, water balance, and osmotic pressures.
• Mineral is required to form bones, nervous tissues and formation of body cells of soft tissues.
• They are required for the proper function of vital organs.
• For the maintenance of acid-base balance in the body.

8. WATER:

Water is the largest constituent of the body. Without water life does not exist. For healthy living water is very essential. Sixty to seventy percent of body consists of water. The proportion of water in the body, however, varies in individuals depending on body composition. It is required for vital functions of body. Body gets water from drinking water or fluids, food (from oxidation of carbohydrates, proteins and fats).

8.1 Distribution of Water

Within the body, water is found in two major compartments- the intracellular compartment (inside the cell) and the extracellular compartment (outside the cell). It is also distributed in blood and lymphatic vessels.

Fifty percent of water is inside the cell known as intracellular water. Twenty percent of water is found outside the cell as extracellular water. Four percent of water is found in the blood. Nine percent of water is found in tissue as interstitial water. Seven percent of water is found in the lymphatic vessels.

8.2 Functions of Water in the Body

Because of its unique chemical and physical characteristics, water plays several key roles in our life processes.

These functions are described below:

• Water as a medium and solvent: Water is the medium of all cell fluids, including digestive juices, lymph, blood, urine and perspiration.
• Water is a solvent for the products of digestion, holding them in solution and permitting them to pass through the absorbing walls of the intestinal tract into the blood stream.
• Water as a lubricant: All fluids have lubricating properties as they can make it easier for the solid materials to slip over one another. Water-based fluids act as lubricants in various parts of the body, most notably within joints where synovial fluid makes movements easier and minimizes wear and tear in cartilage and bone.
• Water as a temperature regulator:
• Water plays an important role in the distribution of heat throughout the body and the regulation of body temperature. Heat is generated in the body due to hard work, exposure to heat, fever or merely by the metabolism of energy-yielding nutrients. The most effective route of heat loss from the body is via the evaporation of water as perspiration from the surface of the skin.
• Water as a source of dietary minerals: The water we drink or use in preparation of food can contain significant amounts of minerals, such as calcium, copper, magnesium, zinc and fluoride. Hard water may contain magnesium and calcium, while the soft water may contain sodium.

8.3 Daily Requirement of Water

The body has no provision for water storage; therefore the amount of water lost every 24 hours must be replaced to maintain health and body efficiency. The precise need for water depends on a person’s body weight and lifestyle. The requirement for water may vary with age; the younger the individual, the greater his/her requirements for water per unit body weight. Our body requires eight glasses or 1500 ml of water or one ml of water for one calorie of food in general.

8.4 Disease Condition

Deficiency of water causes dehydration. It may occur because of inadequate intake, or abnormal loss of body water or a combination of both. The fall in the level of body water associated with dehydration is associated with a fall in blood volume with a subsequent fall in blood pressure. Dehydration causes increased thirst, weakness, loss of appetite, decreased urination, nausea, dryness of skin and mucous membrane, disorientation, delirium and cardiac arrest. Excess retention of water in body causes oedema and fluid collection in the lungs.

9. SUMMARY:

• Food is the very basis of our life. We all need to consume a variety of foods in order to remain healthy. Foods are classified into different food groups: cereal grains and products, pulses and legumes, milk and meat products, fruits and vegetables, and fats & sugars.
• To maintain a good health, we should need all the nutrients in adequate amounts which can be achieved only through the balanced diet and regular physical activity.
• Balanced diet can be defined as one which contains different types of foods in such quantities and proportions that the need for calories, minerals, vitamins, proteins, and other nutrients is adequately met.
• Balanced diet provides all the nutrients in the amount and proportion required to one’s age, sex and activity.
• A balanced diet should provide around 50-60% of total calories from carbohydrate, 10-15% from protein and 20-30% of total calories from fat.
• Carbohydrates are major sources of energy in all human diets. They provide energy of 4 Kcal/g.
• In India, 70-80 % of total dietary calories are derived from carbohydrates present in plant foods such as cereals and millets.
• Proteins are primary structural and functional components of every living cell. They are complex molecules composed of different amino acids.
• Proteins perform a wide range of functions and also provide energy-4Kcal/g and protein requirements vary with age, physiological status and stress.
• Fats are concentrated source of energy providing 9 Kcal/g, and are made up of fatty acids in different proportions. Fats are concentrated source of energy providing 9 Kcal/g, and are made up of fatty acids in different proportions. Excess of fats could lead to obesity, diabetes, cardiovascular diseases and cancer.
• Vitamins are chemical compounds required by the body in small amounts. They must be present in the diet as they cannot be synthesized in the body. They are required for maintenance of the structure of skin, bone, nerves, eye, brain, blood and mucous membrane.
• Minerals are inorganic elements found in body fluids and tissues. They are required for maintenance and integrity of skin, hair, nails, blood and soft tissues.
• Water is the largest constituent of the body and essential constituent of food. For healthy living water is very essential.
• Thus, a well-balanced diet is necessary to meet the nutritional needs of the individual and the family.