Overview — Food for life and health

Food is a basic necessity. Regular supply keeps us fit for all life processes. We eat many foods by taste, availability and body need. This NIOS Module 4 lesson covers food and nutrition, macro- and micronutrients, energy needs, balanced diet for special groups, health and disease, PEM, mineral and vitamin deficiencies, obesity and hypervitaminosis.

After this lesson you should define food, nutrition and disease; classify nutrients; list sources and functions of carbs, fats, proteins, vitamins, minerals, water and roughage; explain energy needs and balanced diet; and describe common deficiency diseases and excess intake problems. Notes follow textbook order only.

Section 1: Food and food groups (28.1)

Food is any substance that (i) yields energy, (ii) builds new cells in growth, (iii) repairs damaged tissues, (iv) aids production of useful body compounds.

Three functional groups:

• Energy foods — rich in carbohydrates and fats (cereals, sugar, oils, jaggery, coconut, groundnut).
• Body-building foods — rich in proteins (legumes, milk, egg, meat, fish, pulses, nuts).
• Protective/regulatory foods — minerals, vitamins, roughage, water (green leafy vegetables, fruits — amla, guava, citrus, watermelon).

Section 2: Nutrition and nutrients (28.2)

Nutrition — sum of processes of taking in, metabolising and using food. Nutrients supply energy, build/repair tissues, regulate metabolism.

Macronutrients (large amounts): carbohydrates, fats, proteins, water. Micronutrients (small amounts): vitamins and minerals. Roughage is also essential though not a classical nutrient.

Energy units: 1 kcal raises 1 L water by 1°C; 1 kcal = 4.18 kJ. Complete oxidation of 1 g carbohydrate ≈ 18 kJ (~4 kcal); 1 g fat ≈ 37 kJ (~9 kcal); 1 g protein ≈ 4 kcal. One glucose molecule → ~38 ATP (1 ATP ≈ 34 kJ; 38×34 = 1292 kJ per mole glucose in textbook calculation). Butter (fat) gives more energy per gram than equal sugar.

Section 3: Carbohydrates (28.2.1)

C, H, O compounds; cheapest energy source; ~60–80% of dietary energy. Types: sugars (mono: glucose, fructose; di: sucrose, maltose, lactose), starch (cereals, potato, roots), cellulose (plant walls — indigestible roughage). Digestion absorbs starch/sugars as glucose; surplus → glycogen in liver. Need ~400–500 g/day for average person; more for growth, lactation, hard work.

Functions: energy; lactose aids Ca absorption and gut bacteria; glycogen/fat stores; cellulose for faecal bulk; glucose is sole energy for CNS.

Section 4: Fats (28.2.2)

Lipids (triglycerides); more C/H, less O than carbs; insoluble in water. Richest energy (~9 kcal/g). Sources: animal (ghee, butter, fish oil, meat, egg); plant (mustard, sunflower, coconut, soy, nuts). Functions: energy; cell membranes; absorb fat-soluble vitamins A,D,E,K; hormone precursors; store; insulation and padding; help vitamin D and steroid synthesis.

Section 5: Proteins (28.2.3)

Large polymers of amino acids; contain N (sometimes P, S). Need: growth, repair, antibodies, enzymes, hormones; also energy (~4 kcal/g). ~22 amino acids; essential must come from diet (e.g. leucine); non-essential body can make (e.g. alanine). Animal proteins (milk, egg, fish, meat) often complete; plant proteins (cereals, pulses) complementary when mixed (dal-roti, sambar-idli). Digestion to amino acids in stomach and small intestine.

Functions: build tissues; enzymes (pepsin, trypsin); hormones (insulin); antibodies; transport (haemoglobin); structure (keratin, collagen, actin, myosin).

Section 6: Vitamins (28.2.4)

Organic micronutrients; biocatalysts; not energy sources. Water-soluble: B-complex, C (excess usually excreted). Fat-soluble: A, D, E, K (can accumulate — toxicity). Body makes little vitamin except D (sunlight).

Sources (examples): B1 — whole grains, yeast, liver (polished rice loses B1 → beri-beri risk). C — amla, citrus, guava. A — milk, carrots, green/yellow vegetables. D — fish liver oil, egg, sunlight. K — green leafy vegetables.

Section 7: Minerals, water, roughage (28.2.5–28.2.7)

Minerals — inorganic salts; no energy but essential for structure and regulation. Major: Ca, P, Na, K, Mg, S, Cl. Trace: Fe, I, Zn, Cu, F, etc.

• Calcium/phosphorus — bones/teeth; nerve/muscle; clotting; deficiency rickets/osteomalacia.
• Iron — haemoglobin; deficiency anaemia (pale, tired, poor appetite).
• Iodine — thyroxine; deficiency goitre, cretinism.
• Na/K — fluid balance, nerve impulse.

Water — ~60% adult body; transport, digestion, excretion, temperature, solvent. From drinks, food, metabolic water.

Roughage — mainly cellulose fibre from fruits/vegetables/cereals; bowel movement, prevents constipation, helps blood sugar and cholesterol control, retains water.

Section 8: Energy needs and balanced diet (28.3–28.4)

Energy need varies with age, sex, occupation, climate, pregnancy, lactation. Examples (kcal/day textbook): sedentary man ~2400; heavy work ~4000; pregnant later half ~3300; lactation ~3700; adolescent boys ~2500. Growing children, labourers, athletes, convalescents, cold climate need more.

Balanced diet — all essential nutrients in suitable proportion and amount for energy and health: meets requirements; mixed foods; adequate energy; maintains health. Sample plate: cereals, dal, vegetables, milk, fruit, limited fat/sugar.

Special needs: children — extra protein, Ca, P, vitamins A,C,D; heavy workers — more carbs/fats; pregnancy/lactation — protein, Ca, Fe, carbs, vitamins; illness/blood loss — protein, iron, vitamins.

Section 9: Health, disease, PEM (28.5)

WHO: health = complete physical, mental and social well-being, not mere absence of disease. Disease = malfunction of body part(s). Deficiency diseases from lack of nutrients. Malnutrition = lack of essential nutrients in diet — harms children’s physical and mental growth.

Three deficiency types: PEM; mineral; vitamin.

PEM (Protein-Energy Malnutrition) in ages 1–5 often: lack of protein and/or carbs, or carbs high relative to protein.

• Marasmus (usually <1 year): severe lack of carbs, fats and proteins — skin and bones, sunken eyes, folded skin, pigeon chest, no oedema, growth failure.
• Kwashiorkor (after weaning to low-protein diet): underweight, moon face, protruding belly, oedema of legs, scaly dark skin, reddish hair, enlarged liver, diarrhoea, anaemia. Cure both with adequate protein + energy foods.

Section 10: Mineral and vitamin deficiencies (28.6–28.7)

Anaemia — iron (and B12) lack; low Hb, pale, tired. Foods: greens, liver, eggs, jaggery, fruits.

Rickets (child) / osteomalacia (adult) — Ca, P, vitamin D; soft/bent bones, bow legs, pigeon chest. Milk, fish liver oil, sun, greens.

Goitre — iodine lack; enlarged thyroid; cretinism if severe in growth (stunted, low IQ). Iodised salt, seafood.

Vitamin deficiency map: A night blindness; B1 beri-beri (polished rice); C scurvy; D rickets; K bleeding; etc. Night blindness: give vitamin A foods (carrot, green leafy, milk, papaya).

Section 11: Obesity and excess (28.8)

Obesity — excess body bulk from stored carb/fat. Causes: overeating, low exercise, hormonal (e.g. low thyroxine). Risks: high cholesterol, hypertension, atherosclerosis, heart attack, diabetes, respiratory problems. Prevention: less fried food and refined carbs; prefer unsaturated oils sparingly; exercise; greens; medical care if hormonal.

Excess iron — hemosiderosis (liver iron deposits); constipation/diarrhoea, nausea, heartburn.

Hypervitaminosis — excess vitamins; water-soluble usually excreted; fat-soluble A and D toxic. Excess A: hair loss, bone pain, nausea. Excess D: high Ca absorption, soft-tissue calcification, weight loss. Both deficiency and excess harm health.

Section 12: Exam map and closed-book drill

Food functions and three groups; nutrition/nutrients; macro/micro; energy values; carb/fat/protein functions; essential amino acids; vitamin table; mineral deficiencies; water and roughage; calorie needs; balanced diet and special groups; WHO health; PEM comparison; anaemia/rickets/goitre; obesity and hypervitaminosis.

Use Formula Sheet; drill 10 MCQs and 20 flashcards. Prioritise PEM differences, vitamin deficiency map, and balanced diet special needs.

Section 13: Extra depth for full coverage

Food is not only calories: body-building proteins and protective micronutrients prevent hidden hunger even when energy is enough. Combining plant proteins in one meal covers essential amino acids cheaply — cultural pairs like dal-roti are nutritionally smart. CNS depends almost only on glucose, so extreme carb restriction can harm brain function.

Fat-soluble vitamins need dietary fat for absorption; very low-fat diets risk A,D,E,K deficiency. Vitamin D is special because sunlight on skin helps synthesis — indoor lifestyle and pollution matter. Polishing rice removes bran rich in B1 — a public-health reason to prefer unpolished grains.

PEM peaks when weaning replaces breast milk with starchy low-protein family food — classic kwashiorkor setting. Marasmus is more total starvation. Oedema distinguishes kwashiorkor; marasmus is pure wasting without fluid swelling.

Pregnancy and lactation double the need for protein, iron and calcium because two bodies are built from one diet. Manual labourers need energy-dense carbs and fats more than office workers. Convalescents need protein and iron to rebuild blood and tissue.

Obesity is malnutrition of excess energy; PEM is malnutrition of deficit — both are “wrong nutrition.” Hypervitaminosis shows that “more vitamins” is not always better. Iron excess and A/D excess prove micronutrients have upper safe limits.

Closed-book drill: (1) four food functions; (2) three food groups; (3) macro vs micro; (4) energy per g of C/F/P; (5) carb types and roughage; (6) fat functions; (7) essential aa + protein mix; (8) water vs fat vitamins; (9) five vitamin deficiency pairs; (10) Fe/I/Ca diseases; (11) water and roughage roles; (12) balanced diet definition; (13) special diet groups; (14) marasmus vs kwashiorkor; (15) obesity causes/prevention; (16) hypervitaminosis A and D. Completing these covers Lesson 28 terminals for Module 4.

Section 14: Expanded review for board exams

Food is any substance that yields energy, builds new cells, repairs tissues and helps make useful body compounds. Classification by function — energy (cereals, sugar, oils), body-building (milk, pulses, meat, eggs) and protective (greens, fruits) — is the first table every student should know cold. Nutrition is the whole path from intake to metabolism; nutrients are the chemical actors that supply energy, build tissue or regulate metabolism.

Macronutrients dominate plate weight: carbohydrates, fats, proteins and water. Micronutrients — vitamins and minerals — are tiny by mass but critical. Energy density matters: fat gives about nine kilocalories per gram, roughly double carbohydrate or protein. The textbook also quotes about eighteen kilojoules per gram carbohydrate and thirty-seven kilojoules per gram fat, with one kilocalorie equal to 4.18 kilojoules. Complete oxidation of glucose yields about thirty-eight ATP molecules — a bridge to cellular respiration lessons.

Carbohydrates include sugars, starch and cellulose. Starch and sugars become glucose; surplus becomes glycogen in the liver. Cellulose is not digested by humans but acts as roughage for bowel movement and metabolic health. A typical adult may need four to five hundred grams of carbohydrate daily; children, lactating mothers and heavy workers need more. Glucose is essentially the only fuel the central nervous system uses under normal conditions. Lactose supports intestinal bacteria and calcium absorption.

Fats are triglycerides rich in carbon and hydrogen. They are the densest energy store, form membranes, carry vitamins A, D, E and K, pad organs, insulate the body and feed synthesis of vitamin D and steroids. Animal ghee and butter and plant oils from mustard, sunflower and coconut are common sources. Equal weights of butter and sugar: butter wins on energy.

Proteins are amino-acid polymers. Essential amino acids must come from food; non-essential ones the body can make. Mixing plant proteins in one meal (dal with roti or sambar with idli) improves amino-acid completeness. Proteins build keratin, collagen and muscle proteins, form enzymes and hormones, act as antibodies and transport oxygen via haemoglobin. Digestion in stomach and intestine frees amino acids for absorption.

Vitamins are biocatalysts needed in milligram or microgram amounts. Water-soluble B and C excess usually leaves in urine; fat-soluble A and D can accumulate and poison (hypervitaminosis). Map deficiencies: thiamine–beri-beri (polished rice risk), riboflavin–mouth cracks, niacin–pellagra, B12–pernicious anaemia, C–scurvy, A–night blindness, D–rickets/osteomalacia, E–reproductive failure, K–bleeding. Sources: amla and citrus for C; carrots and greens for A; sunlight and fish oil for D; leafy greens for K; whole grains and liver for B vitamins.

Minerals do not give calories but build bones (Ca, P), carry oxygen (Fe in haemoglobin), make thyroxine (I), and keep fluid and nerve balance (Na, K). Anaemia, rickets, osteomalacia, goitre and cretinism are the exam mineral/vitamin–mineral cluster. Water is most of body mass and handles transport, temperature and excretion. Roughage (cellulose) prevents constipation and steadies sugar and cholesterol.

Energy need scales with age, sex, occupation, pregnancy and lactation. Sedentary men need less than heavy labourers; later pregnancy and nursing add hundreds of kilocalories and extra protein, calcium and iron. A balanced diet meets all nutrient needs with mixed foods and enough energy. Special plates for children, workers, mothers and convalescents are standard short-answer material.

WHO health is complete well-being, not mere absence of illness. Malnutrition is lack of essential nutrients. PEM produces marasmus (total energy and protein starvation, wasted child without oedema) and kwashiorkor (protein lack after weaning, oedema, moon face, pot belly). Both improve with proper protein and energy feeding. Obesity is excess energy storage with cardiovascular risk. Hypervitaminosis A and D and iron overload show that more is not always better.

Quick formula strip: three food groups; 4/4/9 kcal rule; B/C vs ADEK; A night vision, D bones, C scurvy, B1 beri-beri, Fe anaemia, I goitre; marasmus vs kwashiorkor; balanced diet; obesity prevention. Say each with one food source. You are exam-ready when deficiency maps and PEM differences come without notes on the NIOS Module 4 examination paper for this nutrition lesson.

Section 15: Comparison tables and terminal practice

Marasmus versus kwashiorkor: marasmus is usually in infants under one year with deficiency of carbohydrates, fats and proteins — extreme wasting, sunken eyes, prominent ribs, no oedema. Kwashiorkor appears after weaning onto low-protein starchy food — oedema of legs and face, moon face, pot belly, reddish hair, scaly skin, enlarged liver, diarrhoea. Both need protein- and energy-rich rehabilitation diets.

Rickets versus osteomalacia: both from Ca/P/vitamin D problems; rickets is the childhood form with bow legs and pigeon chest; osteomalacia is adult bone softening and fracture risk. Night blindness needs vitamin A foods such as carrots, papaya, green leafy vegetables, milk and cod liver oil — not only “eye drops.”

Water-soluble versus fat-soluble vitamins: B and C dissolve in water and excess is usually excreted; A, D, E, K need fat for absorption and can accumulate. Essential versus non-essential amino acids: essential cannot be synthesised and must be eaten; non-essential can be made in the body. Body-building foods centre on protein; protective foods centre on vitamins, minerals and roughage.

Why children 1–5 develop PEM: rapid growth raises protein and energy need while poverty, infection and poor weaning foods leave gaps. Why mix proteins: no single plant protein always has all essential amino acids in ideal ratio; combining cereals and pulses covers gaps. Why roughage: softens stool, prevents constipation, and helps metabolic health. Why not only polished rice: bran loss removes thiamine and invites beri-beri — pain, swelling, paralysis risk.

Pregnancy and nursing diets add protein for tissue growth, calcium and phosphorus for bones, iron for blood, and extra carbohydrate for energy of building and milk production. Workers and athletes need energy-dense carbs and fats. Convalescents need protein and iron after blood loss.

Obesity prevention checklist: avoid fried and refined carbs, limit saturated fats, exercise regularly, eat greens, treat hormonal causes medically. Hypervitaminosis A symptoms include hair loss and bone pain; hypervitaminosis D includes high calcium deposits and nausea. Excess iron may cause hemosiderosis and gut pain.

Sources to memorise: vitamin A — milk, carrot, spinach; calcium — milk, greens; iron — liver, spinach, jaggery; B12 — animal foods; starch — rice, wheat, potato; glucose — honey, sweet fruits. Minerals are inorganic elements in salt form needed for structure and regulation, not for calories.

That closes Nutrition and Health: food groups, nutrient chemistry, balanced plates for special groups, and the map of deficiency and excess diseases for Module 4 board revision and short-answer practice.

Sample energy memory: infants need about 100–120 kcal per kg body weight; school children rise toward 1800–2000 kcal; adolescent boys about 2500 and girls about 2200; heavy male labour up to about 4000 kcal. These textbook figures show how profession and life stage change the plate. Health is physical, mental and social — so nutrition policy is also about education and access, not only chemistry of nutrients. You are exam-ready when PEM differences, the vitamin–disease map, and balanced-diet special needs all come without notes on the public examination paper for this Module 4 nutrition and health lesson this year in full for every serious board candidate.