Health: The Ultimate Treasure | Science Grade 8 CBSE

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The six pillars of health

Good health rests on what you eat, how you keep clean, and how your body defends itself. Tap each term to see what it means.

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The three big ideas

Carbohydrates and fats give energy — rice, roti, potato, ghee and oil. Fats also store energy for later.
Proteins build and repair the body — dal, milk, paneer, eggs, nuts. Growing children need them most.
Vitamins and minerals are needed in tiny amounts but are vital — they protect the body and keep it working. Iron makes blood; calcium builds bones; iodine runs the thyroid.
Roughage (fibre from vegetables and whole grains) keeps digestion moving, and water carries nutrients and removes wastes.
A balanced diet supplies all of these in the right proportions — a thali of dal, rice or roti, sabzi, curd and a fruit comes close.

When a nutrient is missing for long, a deficiency disease appears: lack of Vitamin C → scurvy; Vitamin A → night blindness; Vitamin D / calcium → weak bones (rickets); iron → anaemia; iodine → goitre; very low protein → stunted growth.
Most deficiency diseases are prevented and reversed simply by eating the missing nutrient.
Personal hygiene — washing hands with soap, bathing, brushing teeth, clean nails — stops germs from entering the body.
Public hygiene — clean drinking water, covered food, drains, and proper waste disposal — protects the whole community.

Worked example. A market vegetable seller keeps getting a swelling in the front of the neck. A doctor suspects diet. What cheap change could help?

The swelling points to iodine deficiency (goitre). Switching to iodised salt supplies the small daily amount of iodine the thyroid needs — a simple, inexpensive fix.

Common mistake: thinking "more food = better health". Eating a lot of just one type of food can still leave you deficient. Variety and balance matter more than quantity.

Communicable diseases spread from one person to another — through air (cold, TB), water (cholera, typhoid), food, contact, or carriers like mosquitoes (malaria, dengue).
Non-communicable diseases do not spread between people — diabetes, heart disease, and deficiency diseases. Lifestyle and diet play a big role.
Immunity is the body’s built-in defence: white blood cells and other systems recognise and destroy germs.
Vaccines give the immune system a safe "practice run" so it can fight a real germ fast — the reason smallpox is gone and polio nearly so in India.

Common mistake: assuming antibiotics cure every illness. They fight bacteria, not viruses — a viral cold or flu will not respond to them, and overusing them makes bacteria harder to treat.

Where you'll meet it

Health in everyday India

The mid-day meal

School mid-day meals are planned to be balanced — a grain, a pulse for protein, vegetables and sometimes an egg or fruit. The aim is not just to fill children up but to supply the nutrients growing bodies and active minds need.

The pulse polio drive

On vaccination days, health workers give children polio drops across the country. Reaching almost every child is what stops the virus from finding new people to infect — herd protection through immunity in action.

Iodised salt

The simple switch to iodised salt has sharply cut goitre across India. It is a textbook example of preventing a deficiency disease for the whole population at almost no extra cost.

Check yourself

Competency quiz

Modelled on the competency-based pattern — MCQ, assertion–reason and case studies, testing whether you can use the ideas, not just recall them.

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