Food (Classes VI-VIII) • Topic 3 of 4

Balanced Diet and Deficiency Diseases

A balanced diet is one that contains all the nutrients - carbohydrates, proteins, fats, vitamins, minerals, roughage and water - in the right proportions for the body's needs. CTET stresses that 'balanced' depends on the person: a growing child, a labourer and an elderly person need different amounts. When a nutrient is missing over a long time, a deficiency disease results, and this is the single most heavily tested patch of the whole chapter. Memorise these pairs without fail: Vitamin A deficiency causes night blindness; Vitamin C deficiency causes scurvy (bleeding, swollen gums); Vitamin D deficiency causes rickets (soft, bent bones in children) and is linked to calcium absorption; iron deficiency causes anaemia; iodine deficiency causes goitre (swollen thyroid in the neck); and a severe lack of protein causes kwashiorkor (and general protein-energy shortage causes marasmus). Calcium deficiency weakens bones and teeth. On pedagogy, expect questions on how to teach this sensitively and accurately: linking sunlight to Vitamin D, using a local food chart so children plan an affordable balanced thali, and tackling the misconception that costly food is automatically more nutritious, or that being overweight means well-nourished. A good teacher frames deficiency as a public-health issue (why iodised salt is sold, why mid-day meals exist) rather than a personal failing.

✅ Solved examples

1. A villager is diagnosed with goitre. Which nutrient is deficient, and what cheap public-health measure prevents it?
Goitre is caused by a deficiency of iodine (a mineral). The standard, low-cost preventive measure is the use of iodised salt in cooking, which is why iodised salt is widely promoted and sold.
2. A child finds it very hard to see in dim light at dusk. Name the likely deficiency and one food that helps.
This is night blindness, caused by a deficiency of Vitamin A. Foods rich in Vitamin A such as carrots, green leafy vegetables, papaya and milk help prevent it.
3. Match each disease to its missing nutrient: scurvy, rickets, anaemia.
Scurvy - deficiency of Vitamin C; rickets - deficiency of Vitamin D; anaemia - deficiency of iron.
4. A parent says their child eats a lot and is chubby, so the diet must be balanced. From a Science teacher's view, why is this reasoning flawed?
Eating a large quantity or being overweight does not mean the diet is balanced. A balanced diet means all nutrients are present in correct proportions; a child can eat plenty of carbohydrates and fats yet still lack proteins, vitamins or minerals, leading to deficiency despite being chubby.

✏️ Practice — try these, take hints as needed

1. Define a balanced diet in one sentence and state why it differs from person to person.
All nutrients in correct proportion.
Think age, activity, growth.
A balanced diet contains all the nutrients (carbohydrates, proteins, fats, vitamins, minerals, roughage, water) in the right proportions; it differs because needs depend on age, activity level and stage of growth (a child, labourer and elderly person differ).
2. A child has soft, bending leg bones. Name the deficiency disease and the vitamin involved, and one free source of that vitamin.
Bone disease in children.
The "sunshine" vitamin.
Rickets, caused by deficiency of Vitamin D. A free source is sunlight (the skin makes Vitamin D in sunlight).
3. Bleeding and swollen gums point to which deficiency, and which fruits would you recommend?
A vitamin disease.
Think citrus fruits, amla.
Scurvy, caused by deficiency of Vitamin C. Recommend citrus fruits like orange, lemon, and amla (Indian gooseberry).
4. Severe long-term shortage of protein in young children causes which disease?
Protein deficiency disorder.
Starts with K.
Kwashiorkor (severe protein deficiency; general protein-energy shortage can also cause marasmus).

📝 Topic test — 8 questions

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