Everything you eat and drink becomes the fuel and building material for your body. Choosing the right foods in the right amounts keeps you healthy, energetic, and strong. Nutrition is the science of how food affects health and growth.
Why Do We Need Food?
- Food provides the body with:
- Energy to work, play, and think.
- Materials to build and repair body tissues (muscles, bones, skin).
- Protection against diseases.
Nutrients and Their Functions
Food is made up of different substances called nutrients. The main nutrients are:
| Nutrient | Main Function | Good Sources |
|---|---|---|
| Carbohydrates | Provide energy | Rice, wheat, bread, potatoes |
| Proteins | Build and repair tissues | Dal, eggs, milk, fish, nuts |
| Fats | Store energy, protect organs | Butter, oil, nuts, ghee |
| Vitamins | Regulate body processes, prevent disease | Fruits, vegetables |
| Minerals | Build bones, teeth, blood | Milk (calcium), spinach (iron) |
| Water | Transports nutrients, regulates temperature | Water, fruits, vegetables |
| Dietary fibre | Aids digestion | Whole grains, vegetables |
Balanced Diet
- A balanced diet contains all the nutrients in the right proportions for the body's needs. The proportions vary by age, gender, and activity level. A balanced diet includes:
- Plenty of cereals, millets, and pulses.
- Adequate vegetables and fruits.
- Moderate amounts of milk, eggs, and meat.
- Limited sugar, salt, and fats.
Deficiency Diseases
When the diet lacks a particular nutrient for a long time, the body develops a deficiency disease:
- Scurvy — lack of Vitamin C; bleeding gums, weak joints.
- Rickets — lack of Vitamin D and calcium; soft, weak bones in children.
- Anaemia — lack of iron; fatigue, pale skin, weakness.
- Night blindness — lack of Vitamin A; poor vision in dim light.
- Goitre — lack of iodine; swelling of the thyroid gland in the neck.
- Kwashiorkor — severe protein deficiency in young children; swollen belly.
- Marasmus — deficiency of both proteins and calories; extreme thinness.
Vitamins: Fat-soluble vs. Water-soluble
- Fat-soluble vitamins (A, D, E, K) are stored in the body's fat tissues.
- Water-soluble vitamins (B-group, C) are not stored and must be consumed regularly.
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Raju eats mostly plain rice every day and very little vegetables or pulses. Over time, he feels very tired and his gums bleed. His doctor says he has scurvy (Vitamin C deficiency). Adding citrus fruits like oranges or lemons to his diet would cure him.
Priya is a growing child who rarely drinks milk or goes out in sunlight. Her bones are becoming soft and bowed. This is rickets, caused by a deficiency of Vitamin D and calcium. Drinking milk and spending time in sunlight (the body makes Vitamin D from sunlight) would help.
A meal consisting of chapati (carbohydrate), dal (protein), a vegetable curry (vitamins and minerals), curd (calcium), and a piece of fruit (vitamins) is an example of a balanced meal — it includes multiple nutrient groups.
An athlete training hard every day needs more carbohydrates and proteins than a person who is mostly sedentary, because she uses more energy and needs more tissue repair. This shows that nutritional needs differ by activity level.
Spinach is rich in iron, which is needed to make haemoglobin in red blood cells. A person who eats too little iron over time may develop anaemia — feeling constantly tired and pale.
Dietary fibre (found in whole wheat, oats, and vegetables) does not provide energy but is essential for healthy digestion. It adds bulk to food, helping it move through the intestines smoothly and preventing constipation.
People in hilly regions far from the sea may not get enough iodine because their soil and food lack this mineral. Using iodised salt (salt with iodine added) is a simple, affordable solution that prevents goitre in those communities.
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Common mistakes
Common mistakes
Students often think fats are always bad and should be avoided completely. In reality, fats are essential — they store energy, protect organs, help absorb fat-soluble vitamins, and are part of cell membranes. The key is choosing healthy fats (like those in nuts and fish) and avoiding excessive amounts of unhealthy fats (like in fried junk food).
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Summary
- Food provides energy, building materials, and protection against diseases.
- The main nutrients are carbohydrates, proteins, fats, vitamins, minerals, water, and dietary fibre.
- A balanced diet contains all nutrients in the right proportions.
- Deficiency diseases occur when a specific nutrient is missing for a long time (e.g., scurvy from lack of Vitamin C, rickets from lack of Vitamin D).
- Nutritional needs vary with age, gender, and level of physical activity.