What food does for the body, the six nutrients, and the diseases that follow when one is missing.
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Nutrition is the intake and use of food. Food has six components. Carbohydrates (rice, bread, sugar) give quick energy. Proteins (pulses, milk, eggs, fish) build and repair the body. Fats (oil, ghee, butter) give stored energy and insulate. Vitamins and minerals protect health in small amounts. Water takes part in all body reactions and carries wastes. Roughage (fibre) is not digested but prevents constipation. A balanced diet has all of them in correct proportion.
Which food component builds muscles?
Proteins.
Why is roughage needed though it is not digested?
It adds bulk to the food and helps the movement of the intestine, preventing constipation.
Why do growing children need more protein than adults?
They are making new tissue; proteins supply the material for growth and repair.
Fats give the most energy per gram. Using approximate values of 4 kcal per gram for carbohydrate and protein and 9 kcal per gram for fat, we can estimate the energy in a meal. Energy needs depend on age, sex, body size and activity: a person doing heavy work needs more than one with a desk job.
A meal has 60 g carbohydrate, 20 g protein and 15 g fat. Find its energy.
60 × 4 + 20 × 4 + 15 × 9 = 240 + 80 + 135 = 455 kcal.
What percentage of that energy comes from fat?
135 ÷ 455 × 100 = 29.7% (about 30%).
Why does a farmer need more food energy than a clerk?
Heavy physical work uses more energy, so more food must be eaten to replace it.
A lack of a nutrient causes a deficiency disease. Protein lack: kwashiorkor (swollen belly, thin limbs). Lack of both energy and protein: marasmus (very thin body). Vitamin A: night blindness. Vitamin B₁: beriberi. Vitamin C: scurvy. Vitamin D: rickets. Iron: anaemia. Iodine: goitre. Calcium: weak bones and teeth. Eating too much food, especially fat and sugar, causes obesity.
Name the disease caused by lack of (a) vitamin C, (b) vitamin D, (c) iodine.
(a) Scurvy. (b) Rickets. (c) Goitre.
A child has a swollen belly and thin limbs. Which nutrient is likely to be lacking?
Protein (kwashiorkor).
Why is iodised salt recommended?
Iodine is needed to make thyroxine; lack of it causes goitre.
1. What is nutrition?
2. Name the six components of food.
3. What is a balanced diet?
4. Which nutrient gives the most energy per gram?
5. Name two sources of protein.
6. Name the vitamin deficient in night blindness.
7. What mineral is needed to make haemoglobin?
8. Find the energy in 10 g of fat and 25 g of carbohydrate.
9. Differentiate kwashiorkor and marasmus.
10. Why is water essential in the diet?