Learning Objectives
- Identify the major nutrients present in food
- Understand the functions of each nutrient in the body
- Learn about a balanced diet and its importance
- Recognise deficiency diseases and their causes
Key Concepts
Nutrients in Food
The components of food that provide nourishment to the body are called nutrients. There are six main nutrients: carbohydrates, proteins, fats, vitamins, minerals, and water. Carbohydrates and fats are energy-giving foods. Proteins are body-building foods. Vitamins and minerals are protective foods that keep us healthy.
Carbohydrates
Carbohydrates are the main source of energy for our body. They are found in rice, wheat, potatoes, sugar, bread, and corn. Starch and sugar are types of carbohydrates. We can test for starch by adding iodine solution โ it turns blue-black if starch is present.
Proteins
Proteins are needed for the growth and repair of body tissues. They are called body-building foods. Sources include pulses (dal), milk, eggs, meat, fish, cheese, and soybean. Growing children need more proteins. We test for protein using copper sulphate and caustic soda solution โ a violet colour confirms protein.
Fats
Fats give us more energy than carbohydrates and are stored in the body for later use. Sources include butter, ghee, oil, nuts, cheese, and cream. To test for fat, rub the food item on paper โ an oily patch that does not dry shows the presence of fat.
Vitamins and Minerals
Vitamin A: Good for eyes. Found in carrots, papaya, milk. Deficiency causes night blindness.
Vitamin B: Helps in energy release. Found in whole grains, eggs, liver. Deficiency causes beriberi.
Vitamin C: Keeps gums and joints healthy. Found in citrus fruits (orange, lemon, amla). Deficiency causes scurvy.
Vitamin D: Needed for strong bones and teeth. Found in sunlight, fish, eggs. Deficiency causes rickets.
Calcium: Builds strong bones and teeth. Found in milk, cheese, green vegetables.
Iron: Needed for making blood. Found in spinach, jaggery, liver. Deficiency causes anaemia.
Iodine: Needed for the thyroid gland. Found in iodised salt and seafood. Deficiency causes goitre.
Balanced Diet
A diet that contains all the nutrients in the right amounts, along with roughage and water, is called a balanced diet. Roughage (dietary fibre) is the undigested part of food that helps in bowel movement. It is found in whole grains, fruits, and vegetables.
Summary
Food contains nutrients that are essential for our body. Carbohydrates and fats give energy, proteins help in growth and repair, and vitamins and minerals protect us from diseases. A balanced diet includes all nutrients in proper amounts along with roughage and water. Deficiency of nutrients leads to diseases like scurvy, rickets, and anaemia.
Important Terms
- Nutrients: Components of food that nourish the body
- Balanced Diet: A diet containing all nutrients in the right proportions
- Roughage: Dietary fibre that aids digestion (not digested but essential)
- Deficiency Disease: A disease caused by the lack of a specific nutrient
- Scurvy: Disease caused by lack of Vitamin C (bleeding gums)
- Rickets: Disease caused by lack of Vitamin D (weak bones)
- Anaemia: Disease caused by lack of iron (weakness, tiredness)
- Goitre: Disease caused by lack of iodine (swelling of thyroid gland in neck)
Quick Revision
- Six nutrients: carbohydrates, proteins, fats, vitamins, minerals, water
- Energy-giving foods: carbohydrates and fats
- Body-building food: proteins
- Protective foods: vitamins and minerals
- Iodine test for starch โ blue-black colour
- Fat test โ oily patch on paper
- Night blindness โ Vitamin A deficiency; Scurvy โ Vitamin C deficiency
- Roughage helps in digestion and prevents constipation