CH02 Introduction to Nutrition

Nutrition is a vital part of everyone’s life as it is the fundamental step to nurture a Healthier & a Happier body.

Nutrients that we get from food provide the fuel for our bodies to carry out daily activities. Eating a diversified, balanced diet in “Right Portions’ along with appropriate exercises helps us to lead a healthy life.

It is important to educate & empower ourselves with basic understanding of our body functions and how the food we eat, can impact various health outcomes. This will also help us to make more meaningful & informed food choices which will further entail, reducing the risk of many diseases and maintain a healthy lifestyle.

Food is broken down to nutrients by a process called Digestion.

It then gets absorbed and carried to the cells in our body where it performs various functions. We need nutrients for:

  • Providing Energy
  • Growth & Maintenance
  • Regulation of body functions
  • Repair of body tissues
  • Protection of our body

Once the food is digested and absorbed, it undergoes metabolism. Energy metabolism is the method of producing energy from nutrients.

Food energy is released by different components of food like protein, carbohydrate, fat and other organic compounds. Different foods provide different amounts of energy which is measured in units of kilojoules (kJ) or kilocalories (kcal).

One kilocalorie (1 kcal) is equal to 4.18 kilojoules (4.18 kJ).

  • Fat provides 9 kcal (38 kJ) per gram
  • Protein provides 4 kcal (17 kJ) per gram
  • Carbohydrate provides 4 kcal (17 kJ)per gram
  • Alcohol provides 7 kcal (29 kJ) per gram

Understanding Types of Nutrients

Nutrients are broadly classified as Macronutrients and Micronutrients. We all need the same nutrients, but in different quantities depending on age, gender, physiological status and stress.



These provide calories or energy and are required in large amounts to maintain body functions and carry out the activities of daily life.

  3. FATS
  4. WATER
1a. CARBOHYDRATES- Primary source for energy

These are the major sources of energy in all human diets. 60-70% of total dietary calories are derived from carbohydrates. In our food, they exist in different forms such as sugars, starches and dietary fiber. These can be classified into 2 broad parts:

  • Simple Sugars, a class of simple carbohydrates. Present in fruits, vegetables, honey, sugar, milk etc.
  • Complex Starches, a class of complex carbohydrates. Present in cereals, millets, pulses & root vegetable.

Owing to the fact that carbohydrates are the major energy providers, these become an important part in our everyday meal. They not only provide energy, they also aid in regulating blood glucose, break down fatty acids and increase the satiety value.

All Carbohydrates provide 4kcal/gram irrespective of their source.

1b. PROTEIN - Aids growth, Builds & Repairs Muscle Tissue

Proteins are nitrogen-containing substances that are formed by amino acids. They can also be used as energy; however, they are not the primary choice as an energy source.

  • Incomplete proteins, which do not contain all essential amino acids. Present in plant sources as pulses, lentils, soy, nuts such as almonds, groundnuts, wheatgerm.
  • Complete proteins, which contain all essential amino acids. Present in animal sources such as egg, meat, fish, milk, cheese, paneer etc.
Functions of Protein
  • Growth and maintenance of (muscle) tissues
  • Supports Immunity
  • Formation of essential body compounds
  • Providing structural support

Virtually every biochemical reaction in our body is catalyzed by a protein enzyme. All structural tissues of the body contain protein, so the importance of proteins to all aspects of life cannot be overemphasized.

All Proteins provide 4kcal/gram irrespective of their source.

1c. FATS : Vehicle for absorption of Vitamins A, D, E & K. Adds to satiety & flavor

Fats are one of the major sources of energy for the body. They also contribute satiety, flavor, and palatability to the diet.

Types of Fats
  1. Saturated fatty acids such as stearic acid, palmitic acid, lauric acid, etc.
  2. Unsaturated fatty acids
    • Monounsaturated (MUFA) such as oleic acid
    • Polyunsaturated (PUFA) such as omega-3, omega-6.
  3. Trans fat also called as trans-unsaturated fatty acid.


MYTH: Fat should be completely avoided, our body doesn’t need them.

FACT: Your body needs fat. It provides energy just like carbohydrate and protein. They provide essential fatty acids that our body needs. There are fat soluble vitamins such as A, D, E and K which rely on fat for absorption. It also has several roles such as physiological and structural functions, production of hormones, skin care and cognition etc.



Water is the most important nutrient of all and helps in the upkeep of our health. It is the major constituent of our body i.e. about 70%.

Why do we need water?
  • Elimination of body wastes
  • Regulation of body temperature.

The body loses water through sweat, urine and feces. This loss must be constantly made good, with clean and potable water.

MYTH: You can drink water how much ever you want!

FACT: *Like every other nutrient, water should also be consumed in adequate amounts according to individual requirements. Excess consumption will lead to water retention and accumulation in extremities and abdominal region known as oedema. It can also decrease the sodium levels in your body and this condition can be life threatening.

*World Health Organization


These are needed by the body in very small amounts. However, their impact on a body’s health are critical, and deficiency in any of them can cause severe and even life-threatening conditions


Vitamins are organic compounds that are not synthesized by the body and have to be supplied in the diet. They perform a range of functions, including enabling the body to produce enzymes, hormones and other substances needed for normal growth and development. They are classified based on their solubility as

    1. Fat soluble vitamins- Vitamin A, D E, K.
    2. Water soluble vitamins- All B vitamins and Vitamin C

Let’s get to know the roles of few important vitamins

  • Vitamin A- Role in eye & skin health, immunity and growth & development. Found in Fish liver oil, Milk, Eggs, Yellow-Orange fruits & vegetables.
  • Vitamin B- Energy metabolism, formations of blood cells, maintain healthy body tissues. Found in Whole grains, Legumes, Milk, Nuts, Sunflower seeds.
  • Vitamin C- Antioxidant, Immunity, Wound healing. Found in Amla, Citrus fruits, Broccoli, Tomatoes.
  • Vitamin D-Bone health, muscle contractions & absorption of calcium. Found in Sunlight, Liver of fatty fish, Eggs.
  • Vitamin E- Antioxidant, Immunity & formation of cells. Found in Nuts, Seeds, Vegetable oils.
  • Vitamin K- Aids blood clotting & formation of bones. Found in Eggs, Green leafy vegetables, Dairy products.


The nutrient that lacks in a vegetarian diet!

Vitamin B12 is one of the essential nutrients that is involved in nervous system function, red blood cell formation and conversion of food into energy etc., and is mainly found in animal sources such as meat, egg and chicken. People who do not consume animal sources can look for food products that are fortified with Vitamin B12 such as rice & whole wheat.



Classified as:

  • Macro Minerals -Calcium, Magnesium, Phosphorous and Potassium
  • Trace Minerals- Chromium, Copper, Fluoride, Iodine, Iron, Selenium and Zinc

Let’s get to know the roles of few minerals

  • Calcium- Essential for healthy and strong bones and teeth. Present in Milk and milk products, small fish (with bones), legumes, spinach, Chinese cabbage, kale, broccoli etc.
  • Iron- To accept, carry and release oxygen. Adequate intake can help prevent anemia. Present in Red meats, fish, poultry, shellfish, eggs, legumes, grains, dried fruits.
  • Zinc- Aids in Growth & development and supports immunity. Present in meats, some shellfish, legumes, whole grains, and some fortified cereals.


When compared to 13-15 yr. old Adolescents, how much Calcium an Adult Man/Women would require?

It is the same.!

As you grow, your calcium requirements do not get reduced. You need Calcium throughout your life to help develop strong bones and delay the onset of Osteoporosis. Calcium requirements are 1000mg/day for both adults & 13-15 yr. old adolescents.


Apart from supplying nutrients, foods provide a host of other components (non-nutrient phytochemicals) such as antioxidants which have a positive impact on health.

  • Dietary Fibre: Indigestible carbohydrates that has unique roles to play in our body. From increasing satiety to relieving constipation, dietary fiber has a list of proven benefits.
  • Antioxidants: Vitamins C and E, beta-carotene, riboflavin and selenium protect the human body from free radical damage.
  • Phytochemicals- Polyphenols, flavones, etc., also afford protection against oxidant damage.