A Starving Child Can Look Swollen Instead of Thin
Learn what carbohydrates, fats, proteins and water each do, the sources and deficiency diseases of every vitamin and mineral, why roughage matters because it cannot be digested, and how kwashiorkor differs from marasmus.
How can a badly undernourished child look plump rather than thin?
Two children of the same age are both severely undernourished.
One is painfully thin. The ribs show through the skin, the face looks old and drawn, and the skin hangs in loose folds because the fat beneath it has gone.
The other looks almost swollen. The face is puffy, the feet are puffy, the belly is distended — and to anyone judging by appearance the child seems better fed than the first.
Both are starving. The difference is what each diet was short of.
The thin child has been short of food altogether — too little of everything, so the body used up its own fat and muscle. The swollen child has been getting enough energy, usually from starch, but almost no protein, and the lack of protein has let fluid collect in the tissues.
The two conditions have names — marasmus and kwashiorkor — and the swelling is the single feature that separates them.
So "is the child getting enough food?" and "is the child getting the right food?" are two different questions, and a diet can fail either one. That is exactly what makes a balanced diet a separate idea from a sufficient one.
This page covers the first part of the ICSE Class 9 Biology chapter on human anatomy and physiology: what carbohydrates, fats, proteins and water do; the vitamins and minerals with their sources and deficiency diseases; the balanced diet and roughage; and kwashiorkor and marasmus.
One is painfully thin. The ribs show through the skin, the face looks old and drawn, and the skin hangs in loose folds because the fat beneath it has gone.
The other looks almost swollen. The face is puffy, the feet are puffy, the belly is distended — and to anyone judging by appearance the child seems better fed than the first.
Both are starving. The difference is what each diet was short of.
The thin child has been short of food altogether — too little of everything, so the body used up its own fat and muscle. The swollen child has been getting enough energy, usually from starch, but almost no protein, and the lack of protein has let fluid collect in the tissues.
The two conditions have names — marasmus and kwashiorkor — and the swelling is the single feature that separates them.
So "is the child getting enough food?" and "is the child getting the right food?" are two different questions, and a diet can fail either one. That is exactly what makes a balanced diet a separate idea from a sufficient one.
This page covers the first part of the ICSE Class 9 Biology chapter on human anatomy and physiology: what carbohydrates, fats, proteins and water do; the vitamins and minerals with their sources and deficiency diseases; the balanced diet and roughage; and kwashiorkor and marasmus.
What does each of the four main nutrients actually do?
Carbohydrates and fats supply energy, proteins build the body, and water provides the medium in which everything happens.
Carbohydrates — the energy food.
- The body's main and most readily available source of energy, oxidised in respiration to release it
- Sources: rice, wheat, jowar, bajra, potato, sugar, jaggery, banana, bread
- Excess is stored as glycogen in the liver and muscles, and anything beyond that is converted to fat
- Cellulose, a carbohydrate, is not digested at all and serves as roughage
Fats — the concentrated energy food.
- Yield more than twice as much energy per gram as carbohydrates, so they are the body's compact store
- Stored under the skin, where they act as an insulator against heat loss and as a reserve for times of need
- Form an essential part of the cell membrane
- Cushion the delicate organs such as the kidneys and the eyes
- Carry the fat-soluble vitamins A, D, E and K, which cannot be absorbed without them
- Sources: ghee, butter, oil, groundnut, nuts, milk, egg yolk, meat, fish
Proteins — the body-building food.
- Needed for growth — building new tissue — and for the repair and replacement of worn-out cells
- The raw material for enzymes, hormones, haemoglobin and antibodies
- Sources: pulses and dal, soya, gram, milk, curd, paneer, egg, fish, meat, nuts
Water — the medium.
- Forms the largest part of the body by mass
- The medium in which every chemical reaction of the cell takes place
- Transports digested food, oxygen, wastes and hormones in the blood
- Carries out excretion of urea and salts in urine
- Regulates body temperature through sweating
- Keeps the mucous membranes moist, and is the medium in which digestion occurs
- Provides no energy at all
Now a point that matters for the last section of this page. Protein can be burnt for energy if carbohydrates and fats are short — but doing so is both wasteful and harmful, because the body is consuming the very material it needs for building and repair.
So a diet with enough protein but too little carbohydrate leaves a child stunted anyway, because the protein is being diverted into fuel instead of growth. That is the connection between this section and kwashiorkor, and it is why the two energy nutrients are described as protein-sparing: their real service is to leave the protein free to do its own job.
Carbohydrates — the energy food.
- The body's main and most readily available source of energy, oxidised in respiration to release it
- Sources: rice, wheat, jowar, bajra, potato, sugar, jaggery, banana, bread
- Excess is stored as glycogen in the liver and muscles, and anything beyond that is converted to fat
- Cellulose, a carbohydrate, is not digested at all and serves as roughage
Fats — the concentrated energy food.
- Yield more than twice as much energy per gram as carbohydrates, so they are the body's compact store
- Stored under the skin, where they act as an insulator against heat loss and as a reserve for times of need
- Form an essential part of the cell membrane
- Cushion the delicate organs such as the kidneys and the eyes
- Carry the fat-soluble vitamins A, D, E and K, which cannot be absorbed without them
- Sources: ghee, butter, oil, groundnut, nuts, milk, egg yolk, meat, fish
Proteins — the body-building food.
- Needed for growth — building new tissue — and for the repair and replacement of worn-out cells
- The raw material for enzymes, hormones, haemoglobin and antibodies
- Sources: pulses and dal, soya, gram, milk, curd, paneer, egg, fish, meat, nuts
Water — the medium.
- Forms the largest part of the body by mass
- The medium in which every chemical reaction of the cell takes place
- Transports digested food, oxygen, wastes and hormones in the blood
- Carries out excretion of urea and salts in urine
- Regulates body temperature through sweating
- Keeps the mucous membranes moist, and is the medium in which digestion occurs
- Provides no energy at all
Now a point that matters for the last section of this page. Protein can be burnt for energy if carbohydrates and fats are short — but doing so is both wasteful and harmful, because the body is consuming the very material it needs for building and repair.
So a diet with enough protein but too little carbohydrate leaves a child stunted anyway, because the protein is being diverted into fuel instead of growth. That is the connection between this section and kwashiorkor, and it is why the two energy nutrients are described as protein-sparing: their real service is to leave the protein free to do its own job.
What are the sources, functions and deficiency diseases of the vitamins and minerals?
Vitamins and minerals are needed in very small amounts, supply no energy, and a shortage of any one produces its own specific disease.
Vitamin A — carrot, papaya, mango, green leafy vegetables, milk, butter, egg yolk, fish liver oil. Needed for vision in dim light and for healthy skin and mucous membranes. Deficiency: night blindness, and in severe cases drying and damage of the eye.
Vitamin B1 (thiamine) — whole grains, unpolished rice, pulses, yeast, liver. Needed for carbohydrate metabolism and for nerve function. Deficiency: beri-beri, with weakness and nerve damage.
Vitamin B2 (riboflavin) — milk, egg, green vegetables, liver. Deficiency: cracks at the corners of the mouth, sore tongue, scaly skin.
Vitamin B12 — liver, meat, milk, egg. Needed for the formation of red blood cells. Deficiency: pernicious anaemia.
Vitamin C (ascorbic acid) — amla, guava, orange, lemon, tomato, green chilli, sprouted pulses. Needed for healthy gums, teeth and skin, for healing and for resistance to infection. Deficiency: scurvy — bleeding spongy gums, loose teeth, painful joints, slow healing.
Vitamin D (calciferol) — sunlight acting on the skin, fish liver oil, milk, butter, egg yolk. Needed for the absorption of calcium and phosphorus and so for bones and teeth. Deficiency: rickets in children — soft bent bones and bow legs — and osteomalacia in adults.
Vitamin E — vegetable oils, wheat germ, green vegetables. Needed for healthy cell membranes and for reproduction. Deficiency: muscular weakness and sterility.
Vitamin K — green leafy vegetables, tomato, liver, and it is also made by bacteria in the intestine. Needed for the clotting of blood. Deficiency: delayed clotting and excessive bleeding from a small wound.
Calcium — milk, curd, cheese, ragi, green leafy vegetables, small fish eaten with the bones. Needed for bones and teeth, for the clotting of blood, and for nerve and muscle function. Deficiency: rickets, weak bones and teeth, delayed clotting, muscle cramps.
Iodine — iodised salt, sea fish, sea weed, and the drinking water of some regions. Needed by the thyroid gland to make its hormone. Deficiency: goitre — a swelling of the thyroid in the neck — and in children cretinism, with stunted growth and mental retardation.
Iron — green leafy vegetables, jaggery, dates, liver, meat, pulses. Needed to make haemoglobin, which carries oxygen. Deficiency: anaemia — tiredness, pale skin, breathlessness on exertion.
Sodium, taken as common salt — table salt and most foods. Needed to maintain the water and salt balance of the body fluids, and for the conduction of nerve impulses and muscle contraction. Deficiency: muscle cramps, low blood pressure, dehydration. Excess raises blood pressure.
Now two points that are worth more than the lists.
Vitamin D is the one vitamin the body can make for itself, from sunlight acting on the skin. So rickets is as much a disease of sunlight deprivation as of diet — and in a country with abundant sunshine it usually reflects staying indoors or keeping the skin covered rather than a shortage of food.
And vitamin D and calcium must be learnt together. Calcium in the diet is useless if there is no vitamin D to absorb it, so a child with plenty of milk and no sunlight can still develop rickets. A question asking why rickets occurs despite a calcium-rich diet wants exactly that — the mineral was present and the vitamin that lets it in was not.
Vitamin A — carrot, papaya, mango, green leafy vegetables, milk, butter, egg yolk, fish liver oil. Needed for vision in dim light and for healthy skin and mucous membranes. Deficiency: night blindness, and in severe cases drying and damage of the eye.
Vitamin B1 (thiamine) — whole grains, unpolished rice, pulses, yeast, liver. Needed for carbohydrate metabolism and for nerve function. Deficiency: beri-beri, with weakness and nerve damage.
Vitamin B2 (riboflavin) — milk, egg, green vegetables, liver. Deficiency: cracks at the corners of the mouth, sore tongue, scaly skin.
Vitamin B12 — liver, meat, milk, egg. Needed for the formation of red blood cells. Deficiency: pernicious anaemia.
Vitamin C (ascorbic acid) — amla, guava, orange, lemon, tomato, green chilli, sprouted pulses. Needed for healthy gums, teeth and skin, for healing and for resistance to infection. Deficiency: scurvy — bleeding spongy gums, loose teeth, painful joints, slow healing.
Vitamin D (calciferol) — sunlight acting on the skin, fish liver oil, milk, butter, egg yolk. Needed for the absorption of calcium and phosphorus and so for bones and teeth. Deficiency: rickets in children — soft bent bones and bow legs — and osteomalacia in adults.
Vitamin E — vegetable oils, wheat germ, green vegetables. Needed for healthy cell membranes and for reproduction. Deficiency: muscular weakness and sterility.
Vitamin K — green leafy vegetables, tomato, liver, and it is also made by bacteria in the intestine. Needed for the clotting of blood. Deficiency: delayed clotting and excessive bleeding from a small wound.
Calcium — milk, curd, cheese, ragi, green leafy vegetables, small fish eaten with the bones. Needed for bones and teeth, for the clotting of blood, and for nerve and muscle function. Deficiency: rickets, weak bones and teeth, delayed clotting, muscle cramps.
Iodine — iodised salt, sea fish, sea weed, and the drinking water of some regions. Needed by the thyroid gland to make its hormone. Deficiency: goitre — a swelling of the thyroid in the neck — and in children cretinism, with stunted growth and mental retardation.
Iron — green leafy vegetables, jaggery, dates, liver, meat, pulses. Needed to make haemoglobin, which carries oxygen. Deficiency: anaemia — tiredness, pale skin, breathlessness on exertion.
Sodium, taken as common salt — table salt and most foods. Needed to maintain the water and salt balance of the body fluids, and for the conduction of nerve impulses and muscle contraction. Deficiency: muscle cramps, low blood pressure, dehydration. Excess raises blood pressure.
Now two points that are worth more than the lists.
Vitamin D is the one vitamin the body can make for itself, from sunlight acting on the skin. So rickets is as much a disease of sunlight deprivation as of diet — and in a country with abundant sunshine it usually reflects staying indoors or keeping the skin covered rather than a shortage of food.
And vitamin D and calcium must be learnt together. Calcium in the diet is useless if there is no vitamin D to absorb it, so a child with plenty of milk and no sunlight can still develop rickets. A question asking why rickets occurs despite a calcium-rich diet wants exactly that — the mineral was present and the vitamin that lets it in was not.
What makes a diet balanced, and why does the body need something it cannot digest?
A balanced diet contains all the nutrients — carbohydrates, fats, proteins, vitamins, minerals and water — together with roughage, in the right proportions and the right quantity for that person.
Both halves of that definition matter. A diet containing every nutrient can still be unbalanced if the proportions are wrong, and a perfectly proportioned diet can still be inadequate if there is too little of it.
What the right proportions depend on.
- Age — a growing child needs proportionally more protein and calcium than an adult
- Sex and body size
- Occupation — a manual labourer needs far more energy than a person doing desk work
- Climate — more energy is needed in a cold climate, and more water and salt in a hot one
- State of health — a pregnant or nursing mother needs extra protein, calcium and iron; a patient recovering from illness or surgery needs extra protein for repair
Why a balanced diet matters: proper growth and development, enough energy for the day's work, resistance to infection, repair of worn-out tissue, and avoidance of both deficiency diseases and obesity.
Roughage — the component that is valuable because it cannot be digested.
Roughage is cellulose, the fibre of plant cell walls. Humans produce no enzyme that can digest cellulose, so every bit of it passes through the alimentary canal unchanged and is never absorbed.
Sources: whole grains and unrefined cereals, the skins of fruits and vegetables, salad, green leafy vegetables, pulses.
What it does.
- It adds bulk to the food in the intestine
- It holds water, keeping the contents soft
- The bulk stimulates the muscles of the intestinal wall, so that peristalsis is strong and regular and the waste moves along
- It therefore prevents constipation, and with it the disorders that follow from straining and from waste remaining too long in the bowel
Now the point that is genuinely worth noticing. Every other item in a balanced diet is there to be absorbed. Carbohydrate, fat, protein, vitamins, minerals and water are all wanted inside the body.
Roughage is the one component whose whole value lies in NOT being absorbed. It works mechanically, on the way through, and then leaves. A question asking why roughage is included in a balanced diet when it has no food value is answered by exactly that — it is not a nutrient at all, it is a stimulus to the intestine.
And that explains a modern problem in one line. A diet of refined flour, polished rice, sugar and processed food has had most of its fibre removed in the milling. So it can be rich in energy, adequate in protein and still cause constipation, which is why whole grains, fruit with the skin on and plenty of vegetables are recommended alongside whatever else is eaten.
Both halves of that definition matter. A diet containing every nutrient can still be unbalanced if the proportions are wrong, and a perfectly proportioned diet can still be inadequate if there is too little of it.
What the right proportions depend on.
- Age — a growing child needs proportionally more protein and calcium than an adult
- Sex and body size
- Occupation — a manual labourer needs far more energy than a person doing desk work
- Climate — more energy is needed in a cold climate, and more water and salt in a hot one
- State of health — a pregnant or nursing mother needs extra protein, calcium and iron; a patient recovering from illness or surgery needs extra protein for repair
Why a balanced diet matters: proper growth and development, enough energy for the day's work, resistance to infection, repair of worn-out tissue, and avoidance of both deficiency diseases and obesity.
Roughage — the component that is valuable because it cannot be digested.
Roughage is cellulose, the fibre of plant cell walls. Humans produce no enzyme that can digest cellulose, so every bit of it passes through the alimentary canal unchanged and is never absorbed.
Sources: whole grains and unrefined cereals, the skins of fruits and vegetables, salad, green leafy vegetables, pulses.
What it does.
- It adds bulk to the food in the intestine
- It holds water, keeping the contents soft
- The bulk stimulates the muscles of the intestinal wall, so that peristalsis is strong and regular and the waste moves along
- It therefore prevents constipation, and with it the disorders that follow from straining and from waste remaining too long in the bowel
Now the point that is genuinely worth noticing. Every other item in a balanced diet is there to be absorbed. Carbohydrate, fat, protein, vitamins, minerals and water are all wanted inside the body.
Roughage is the one component whose whole value lies in NOT being absorbed. It works mechanically, on the way through, and then leaves. A question asking why roughage is included in a balanced diet when it has no food value is answered by exactly that — it is not a nutrient at all, it is a stimulus to the intestine.
And that explains a modern problem in one line. A diet of refined flour, polished rice, sugar and processed food has had most of its fibre removed in the milling. So it can be rich in energy, adequate in protein and still cause constipation, which is why whole grains, fruit with the skin on and plenty of vegetables are recommended alongside whatever else is eaten.
How do kwashiorkor and marasmus differ, and how are they prevented?
Kwashiorkor is a severe deficiency of protein with adequate energy; marasmus is a severe deficiency of food altogether. The presence of swelling is what separates them.
Malnutrition means a diet lacking one or more nutrients, or wrongly balanced in them. It covers under-nutrition — too little food — and over-nutrition — too much, leading to obesity.
Kwashiorkor.
- Cause: a severe shortage of protein, while the energy intake from carbohydrate may be adequate or nearly so
- Who: usually children of about one to three years, typically after being weaned from milk onto a diet of starchy food — rice, gruel, roti — with almost no protein in it
- Symptoms: stunted growth; oedema — swelling of the face, feet, hands and abdomen from fluid collecting in the tissues, so the child may look plump; a pot belly with an enlarged liver; thin, brittle, discoloured hair that comes out easily; flaky, patchy skin that peels; loss of appetite; irritability alternating with apathy; anaemia; and slow mental development
Marasmus.
- Cause: a severe shortage of both protein and energy — of food in general
- Who: usually infants under one year, often where breast-feeding stopped very early and no adequate substitute followed
- Symptoms: extreme wasting — the child is very thin, with the ribs clearly visible; no oedema; loss of the fat beneath the skin, so the skin hangs in loose folds and the face looks wrinkled and aged; body weight far below normal for the age; dry thin skin; diarrhoea; and the child is alert but persistently hungry
The one feature that separates them. Oedema is present in kwashiorkor and absent in marasmus. A kwashiorkor child appears swollen; a marasmus child appears emaciated — and both are starving.
So appearance is actively misleading in one of the two cases, which is the whole reason the two conditions have separate names. A question asking how the two are distinguished wants the oedema, and "one is thinner" is only half of it.
A second difference worth stating. The kwashiorkor child has usually been getting enough calories and is therefore often listless and uninterested in food; the marasmus child has been getting too few and is hungry. The behaviour matches the cause.
Prevention of both.
- A balanced diet with adequate protein from affordable local sources — pulses and dal, groundnut, soya, ragi, milk, curd, egg
- Continue breast-feeding as long as possible, and when weaning begins introduce protein-containing food and not starch alone
- Combine cereals with pulses — the traditional dal and rice or khichdi together supply better protein than either alone
- Immunisation, and prompt treatment of infections and worms, which rob a child of nutrients
- Nutrition education for families, and supplementary feeding for children and mothers
- Clean water, hygiene and sanitary disposal of waste, to prevent the repeated diarrhoea that makes malnutrition worse
Both conditions are treatable if caught early, by careful feeding that restores protein and energy gradually. And both are preventable with food that is already grown and eaten in India — which is why the answer to a prevention question is about the composition of the diet rather than about expensive food.
Malnutrition means a diet lacking one or more nutrients, or wrongly balanced in them. It covers under-nutrition — too little food — and over-nutrition — too much, leading to obesity.
Kwashiorkor.
- Cause: a severe shortage of protein, while the energy intake from carbohydrate may be adequate or nearly so
- Who: usually children of about one to three years, typically after being weaned from milk onto a diet of starchy food — rice, gruel, roti — with almost no protein in it
- Symptoms: stunted growth; oedema — swelling of the face, feet, hands and abdomen from fluid collecting in the tissues, so the child may look plump; a pot belly with an enlarged liver; thin, brittle, discoloured hair that comes out easily; flaky, patchy skin that peels; loss of appetite; irritability alternating with apathy; anaemia; and slow mental development
Marasmus.
- Cause: a severe shortage of both protein and energy — of food in general
- Who: usually infants under one year, often where breast-feeding stopped very early and no adequate substitute followed
- Symptoms: extreme wasting — the child is very thin, with the ribs clearly visible; no oedema; loss of the fat beneath the skin, so the skin hangs in loose folds and the face looks wrinkled and aged; body weight far below normal for the age; dry thin skin; diarrhoea; and the child is alert but persistently hungry
The one feature that separates them. Oedema is present in kwashiorkor and absent in marasmus. A kwashiorkor child appears swollen; a marasmus child appears emaciated — and both are starving.
So appearance is actively misleading in one of the two cases, which is the whole reason the two conditions have separate names. A question asking how the two are distinguished wants the oedema, and "one is thinner" is only half of it.
A second difference worth stating. The kwashiorkor child has usually been getting enough calories and is therefore often listless and uninterested in food; the marasmus child has been getting too few and is hungry. The behaviour matches the cause.
Prevention of both.
- A balanced diet with adequate protein from affordable local sources — pulses and dal, groundnut, soya, ragi, milk, curd, egg
- Continue breast-feeding as long as possible, and when weaning begins introduce protein-containing food and not starch alone
- Combine cereals with pulses — the traditional dal and rice or khichdi together supply better protein than either alone
- Immunisation, and prompt treatment of infections and worms, which rob a child of nutrients
- Nutrition education for families, and supplementary feeding for children and mothers
- Clean water, hygiene and sanitary disposal of waste, to prevent the repeated diarrhoea that makes malnutrition worse
Both conditions are treatable if caught early, by careful feeding that restores protein and energy gradually. And both are preventable with food that is already grown and eaten in India — which is why the answer to a prevention question is about the composition of the diet rather than about expensive food.
Exam tip
Exam tip: give the source, the function and the deficiency together
For each nutrient give the FUNCTION first. Carbohydrates and fats — energy; proteins — growth and repair; water — the medium and transport.
Fats yield more than twice the energy of carbohydrates per gram, and they carry the fat-soluble vitamins A, D, E and K.
Proteins make enzymes, hormones, haemoglobin and antibodies — say this as well as "body-building".
Water provides no energy. State it; it is often asked.
For every vitamin and mineral give all three — source, function, deficiency disease. A deficiency disease named without its vitamin earns little.
Learn the classic pairings: A — night blindness; B1 — beri-beri; B12 — pernicious anaemia; C — scurvy; D — rickets in children and osteomalacia in adults; K — delayed clotting; calcium — rickets and weak bones; iodine — goitre and cretinism; iron — anaemia.
Vitamin D comes from SUNLIGHT as well as food, and it is needed to absorb calcium — so rickets can occur on a calcium-rich diet with no sunlight.
Define a balanced diet with both halves — all the nutrients plus roughage, in the right proportions and the right quantity — then list what the proportions depend on.
Roughage is cellulose and is NOT digested. Say it adds bulk, holds water, stimulates peristalsis and prevents constipation.
Kwashiorkor — PROTEIN deficiency with adequate energy, with OEDEMA. Marasmus — deficiency of protein AND energy, with NO oedema.
The oedema is the distinguishing feature — name it explicitly in a comparison.
And for prevention, name cheap local protein sources — pulses, groundnut, soya, ragi, milk — and say continue breast-feeding and wean onto protein, not starch alone.
Fats yield more than twice the energy of carbohydrates per gram, and they carry the fat-soluble vitamins A, D, E and K.
Proteins make enzymes, hormones, haemoglobin and antibodies — say this as well as "body-building".
Water provides no energy. State it; it is often asked.
For every vitamin and mineral give all three — source, function, deficiency disease. A deficiency disease named without its vitamin earns little.
Learn the classic pairings: A — night blindness; B1 — beri-beri; B12 — pernicious anaemia; C — scurvy; D — rickets in children and osteomalacia in adults; K — delayed clotting; calcium — rickets and weak bones; iodine — goitre and cretinism; iron — anaemia.
Vitamin D comes from SUNLIGHT as well as food, and it is needed to absorb calcium — so rickets can occur on a calcium-rich diet with no sunlight.
Define a balanced diet with both halves — all the nutrients plus roughage, in the right proportions and the right quantity — then list what the proportions depend on.
Roughage is cellulose and is NOT digested. Say it adds bulk, holds water, stimulates peristalsis and prevents constipation.
Kwashiorkor — PROTEIN deficiency with adequate energy, with OEDEMA. Marasmus — deficiency of protein AND energy, with NO oedema.
The oedema is the distinguishing feature — name it explicitly in a comparison.
And for prevention, name cheap local protein sources — pulses, groundnut, soya, ragi, milk — and say continue breast-feeding and wean onto protein, not starch alone.
Did you know
Why dal and rice together beat either one alone
A plate of dal and rice is one of the most ordinary meals in India, and it is also a rather clever piece of nutrition that nobody designed on purpose.
Proteins are built from about twenty different building blocks, and the body cannot make all of them for itself. A handful must come ready-made from food, and a protein source is only as useful as its scarcest building block — because once that one runs out, the rest cannot be assembled into anything.
Rice is short of one of them. Pulses are short of a different one. So a meal of rice alone or dal alone falls short in whichever block that food happens to lack, however much of it is eaten.
Put the two together and each supplies what the other is missing. The mixture is markedly better than either half, and better than you would expect from simply adding them up.
The same combination turns up everywhere, under different names and with different grains. Roti with dal. Idli made of rice and urad dal together. Khichdi. Rajma with rice. Bread with beans. Cereal plus pulse, in every case.
None of this was worked out from a table of nutrients. It was arrived at by people cooking what grew locally and noticing, over a very long time, which combinations kept a family well. The chemistry was correct long before anybody could have explained it.
There is a practical lesson in it for answering exam questions about diet. The cheapest way to improve the protein in a poor diet is almost never to add meat or milk. It is to combine what is already there — to put a pulse beside the cereal that was going to be eaten anyway.
A nutritional problem can have a cooking solution rather than a shopping one, and that is exactly why prevention of kwashiorkor is usually described in terms of the composition of the meal rather than its cost.
Proteins are built from about twenty different building blocks, and the body cannot make all of them for itself. A handful must come ready-made from food, and a protein source is only as useful as its scarcest building block — because once that one runs out, the rest cannot be assembled into anything.
Rice is short of one of them. Pulses are short of a different one. So a meal of rice alone or dal alone falls short in whichever block that food happens to lack, however much of it is eaten.
Put the two together and each supplies what the other is missing. The mixture is markedly better than either half, and better than you would expect from simply adding them up.
The same combination turns up everywhere, under different names and with different grains. Roti with dal. Idli made of rice and urad dal together. Khichdi. Rajma with rice. Bread with beans. Cereal plus pulse, in every case.
None of this was worked out from a table of nutrients. It was arrived at by people cooking what grew locally and noticing, over a very long time, which combinations kept a family well. The chemistry was correct long before anybody could have explained it.
There is a practical lesson in it for answering exam questions about diet. The cheapest way to improve the protein in a poor diet is almost never to add meat or milk. It is to combine what is already there — to put a pulse beside the cereal that was going to be eaten anyway.
A nutritional problem can have a cooking solution rather than a shopping one, and that is exactly why prevention of kwashiorkor is usually described in terms of the composition of the meal rather than its cost.
Exam relevance
Why does NEET keep returning to vitamins and deficiency diseases?
Because vitamin-to-deficiency matching is one of the most efficient question types there is, and it is asked in both chemistry and biology.
This is the foundation for Class 11 Biology Digestion and Absorption and Class 12 Chemistry Biomolecules, examined in NEET. Digestion and Absorption ends with nutritional and digestive disorders, naming kwashiorkor, marasmus, indigestion, constipation, vomiting, diarrhoea and jaundice — so the two forms of protein-energy malnutrition described here are examined by name in that chapter, with the same distinguishing features.
The vitamins are examined in two subjects at once. Class 12 Chemistry Biomolecules classifies them into fat-soluble — A, D, E and K — and water-soluble — the B group and C — and lists the deficiency disease of each. Match-the-column questions pairing a vitamin with its deficiency or with its solubility are among the most predictable items in both NEET and JEE Main, and the fat-soluble group is the same group this page notes as needing fats to be absorbed.
The solubility distinction has a consequence that is examined. Water-soluble vitamins are not stored in the body and must be supplied regularly, while fat-soluble ones are stored and can build up to harmful levels. So a question asking which vitamin can cause harm in excess is asking about solubility, and the answer follows from the classification rather than from memory.
Biomolecules covers the nutrients themselves. Class 12 Chemistry treats carbohydrates — monosaccharides, disaccharides and polysaccharides including cellulose and glycogen — proteins and their amino acids, lipids, enzymes and hormones. The reason humans cannot digest cellulose is given there: no enzyme in the human gut can break its particular linkage, while the linkage in starch can be broken. That is the molecular version of the roughage point made on this page.
Mineral deficiency carries into physiology. Iron and haemoglobin appear in Class 11 Body Fluids and Circulation and in the anaemias; iodine and the thyroid appear in Chemical Coordination and Integration, where goitre, cretinism and hypothyroidism are examined; calcium appears in Locomotion and Movement for bone and in muscle contraction, and in blood clotting. So each mineral on this page reappears attached to an organ system.
Protein-sparing and metabolism appear in respiration. Class 11 explains that protein is used for energy only when carbohydrate and fat are short, and the respiratory quotient differs for a carbohydrate, a fat and a protein — which is the quantitative version of the point made here.
Balanced diet appears in the applied chapters. Class 12 Strategies for Enhancement in Food Production covers biofortification — breeding crops with more protein, vitamins and minerals — and names improved varieties richer in iron, protein and vitamin A. The prevention argument on this page is what that programme is designed to deliver.
What the questions look like. For board work, expect state the functions of carbohydrates, fats, proteins and water, give the source, function and deficiency disease of a named vitamin or mineral, define a balanced diet and state what it depends on, explain the role of roughage, and distinguish kwashiorkor from marasmus. Every nutrient answer wants all three parts. For NEET, expect vitamin-to-deficiency matching, fat-soluble against water-soluble classification, the kwashiorkor-marasmus distinction and hormone-mineral links.
How board and competitive emphasis differ. A board paper rewards the source, function and deficiency given together. A competitive paper assumes the pairing and asks about solubility, storage, or which gland a mineral serves.
The single trap that costs the most marks. Saying that a kwashiorkor child is thin. The oedema makes the child look swollen — the face, feet and abdomen are puffy with retained fluid — and it is the marasmus child who is visibly wasted with ribs showing. The defence is to attach the oedema to kwashiorkor as part of the definition, because once "protein deficiency with oedema" and "protein-and-energy deficiency without oedema" are learnt as two complete phrases, no comparison question can reverse them.
This is the foundation for Class 11 Biology Digestion and Absorption and Class 12 Chemistry Biomolecules, examined in NEET. Digestion and Absorption ends with nutritional and digestive disorders, naming kwashiorkor, marasmus, indigestion, constipation, vomiting, diarrhoea and jaundice — so the two forms of protein-energy malnutrition described here are examined by name in that chapter, with the same distinguishing features.
The vitamins are examined in two subjects at once. Class 12 Chemistry Biomolecules classifies them into fat-soluble — A, D, E and K — and water-soluble — the B group and C — and lists the deficiency disease of each. Match-the-column questions pairing a vitamin with its deficiency or with its solubility are among the most predictable items in both NEET and JEE Main, and the fat-soluble group is the same group this page notes as needing fats to be absorbed.
The solubility distinction has a consequence that is examined. Water-soluble vitamins are not stored in the body and must be supplied regularly, while fat-soluble ones are stored and can build up to harmful levels. So a question asking which vitamin can cause harm in excess is asking about solubility, and the answer follows from the classification rather than from memory.
Biomolecules covers the nutrients themselves. Class 12 Chemistry treats carbohydrates — monosaccharides, disaccharides and polysaccharides including cellulose and glycogen — proteins and their amino acids, lipids, enzymes and hormones. The reason humans cannot digest cellulose is given there: no enzyme in the human gut can break its particular linkage, while the linkage in starch can be broken. That is the molecular version of the roughage point made on this page.
Mineral deficiency carries into physiology. Iron and haemoglobin appear in Class 11 Body Fluids and Circulation and in the anaemias; iodine and the thyroid appear in Chemical Coordination and Integration, where goitre, cretinism and hypothyroidism are examined; calcium appears in Locomotion and Movement for bone and in muscle contraction, and in blood clotting. So each mineral on this page reappears attached to an organ system.
Protein-sparing and metabolism appear in respiration. Class 11 explains that protein is used for energy only when carbohydrate and fat are short, and the respiratory quotient differs for a carbohydrate, a fat and a protein — which is the quantitative version of the point made here.
Balanced diet appears in the applied chapters. Class 12 Strategies for Enhancement in Food Production covers biofortification — breeding crops with more protein, vitamins and minerals — and names improved varieties richer in iron, protein and vitamin A. The prevention argument on this page is what that programme is designed to deliver.
What the questions look like. For board work, expect state the functions of carbohydrates, fats, proteins and water, give the source, function and deficiency disease of a named vitamin or mineral, define a balanced diet and state what it depends on, explain the role of roughage, and distinguish kwashiorkor from marasmus. Every nutrient answer wants all three parts. For NEET, expect vitamin-to-deficiency matching, fat-soluble against water-soluble classification, the kwashiorkor-marasmus distinction and hormone-mineral links.
How board and competitive emphasis differ. A board paper rewards the source, function and deficiency given together. A competitive paper assumes the pairing and asks about solubility, storage, or which gland a mineral serves.
The single trap that costs the most marks. Saying that a kwashiorkor child is thin. The oedema makes the child look swollen — the face, feet and abdomen are puffy with retained fluid — and it is the marasmus child who is visibly wasted with ribs showing. The defence is to attach the oedema to kwashiorkor as part of the definition, because once "protein deficiency with oedema" and "protein-and-energy deficiency without oedema" are learnt as two complete phrases, no comparison question can reverse them.
Key takeaways
Nutrients, deficiency diseases and malnutrition: quick revision
- Carbohydrates — the main, readily available energy source. Rice, wheat, jowar, potato, sugar, jaggery. Excess stored as glycogen in liver and muscle, then as fat. Cellulose is the indigestible one.
- Fats — concentrated energy, over twice as much per gram; stored under the skin as an insulator and reserve; part of the cell membrane; cushion organs; carry the fat-soluble vitamins A, D, E, K. Ghee, oil, nuts, milk, egg yolk.
- Proteins — growth, and repair and replacement of tissue; the raw material for enzymes, hormones, haemoglobin and antibodies. Pulses, soya, gram, milk, curd, paneer, egg, fish, meat.
- Water — the medium for every cell reaction; transport in the blood; excretion in urine; temperature regulation by sweating; keeps membranes moist. Provides no energy.
- Carbohydrates and fats are protein-sparing — with too little of them, protein is burnt for fuel instead of building, so growth fails.
- Vitamin A — carrot, papaya, green leafy vegetables, milk, fish liver oil. Dim-light vision and healthy skin. Deficiency night blindness.
- B1 — whole grains, unpolished rice, pulses. Carbohydrate metabolism and nerves. Deficiency beri-beri.
- B2 — milk, egg, green vegetables. Deficiency cracks at the corners of the mouth, sore tongue.
- B12 — liver, meat, milk, egg. Red blood cell formation. Deficiency pernicious anaemia.
- C — amla, guava, citrus, tomato, sprouts. Gums, teeth, healing, resistance. Deficiency scurvy.
- D — sunlight, fish liver oil, milk, egg yolk. Absorption of calcium and phosphorus. Deficiency rickets in children, osteomalacia in adults.
- E — vegetable oils, wheat germ. Cell membranes and reproduction. Deficiency weakness, sterility.
- K — green leafy vegetables, and intestinal bacteria. Clotting of blood. Deficiency delayed clotting.
- Calcium — milk, curd, ragi, green leafy vegetables. Bones and teeth, clotting, nerve and muscle function. Deficiency rickets, weak bones, cramps.
- Iodine — iodised salt, sea fish. Needed by the thyroid. Deficiency goitre, and cretinism in children.
- Iron — green leafy vegetables, jaggery, dates, liver, pulses. Makes haemoglobin. Deficiency anaemia.
- Sodium — common salt. Water and salt balance, nerve impulses, muscle contraction. Deficiency cramps and low blood pressure; excess raises blood pressure.
- Vitamin D is made by the body from sunlight, and calcium cannot be absorbed without it — so rickets can occur on a calcium-rich diet with no sunlight.
- Balanced diet — all the nutrients plus roughage, in the right proportions and quantity, varying with age, sex, body size, occupation, climate and health.
- Roughage is cellulose, not digested at all. It adds bulk, holds water, stimulates peristalsis and prevents constipation — the one component valuable because it is not absorbed.
- Kwashiorkor — protein deficiency with adequate energy; children of one to three; oedema of face, feet and abdomen, pot belly, enlarged liver, thin discoloured hair, flaky skin, loss of appetite, anaemia, stunted growth.
- Marasmus — deficiency of protein AND energy; infants under one; extreme wasting, ribs visible, no oedema, loss of subcutaneous fat, skin in folds, aged face, persistent hunger.
- Oedema present in kwashiorkor and absent in marasmus is the distinguishing feature.
- Prevention — a balanced diet with cheap local protein (pulses, groundnut, soya, ragi, milk), continued breast-feeding, weaning onto protein not starch alone, cereal plus pulse together, immunisation, deworming, clean water and nutrition education.
Cover the vitamin list and name the deficiency disease of each in ten seconds — then say which two of them can be caused without any shortage of food at all.
- Fats — concentrated energy, over twice as much per gram; stored under the skin as an insulator and reserve; part of the cell membrane; cushion organs; carry the fat-soluble vitamins A, D, E, K. Ghee, oil, nuts, milk, egg yolk.
- Proteins — growth, and repair and replacement of tissue; the raw material for enzymes, hormones, haemoglobin and antibodies. Pulses, soya, gram, milk, curd, paneer, egg, fish, meat.
- Water — the medium for every cell reaction; transport in the blood; excretion in urine; temperature regulation by sweating; keeps membranes moist. Provides no energy.
- Carbohydrates and fats are protein-sparing — with too little of them, protein is burnt for fuel instead of building, so growth fails.
- Vitamin A — carrot, papaya, green leafy vegetables, milk, fish liver oil. Dim-light vision and healthy skin. Deficiency night blindness.
- B1 — whole grains, unpolished rice, pulses. Carbohydrate metabolism and nerves. Deficiency beri-beri.
- B2 — milk, egg, green vegetables. Deficiency cracks at the corners of the mouth, sore tongue.
- B12 — liver, meat, milk, egg. Red blood cell formation. Deficiency pernicious anaemia.
- C — amla, guava, citrus, tomato, sprouts. Gums, teeth, healing, resistance. Deficiency scurvy.
- D — sunlight, fish liver oil, milk, egg yolk. Absorption of calcium and phosphorus. Deficiency rickets in children, osteomalacia in adults.
- E — vegetable oils, wheat germ. Cell membranes and reproduction. Deficiency weakness, sterility.
- K — green leafy vegetables, and intestinal bacteria. Clotting of blood. Deficiency delayed clotting.
- Calcium — milk, curd, ragi, green leafy vegetables. Bones and teeth, clotting, nerve and muscle function. Deficiency rickets, weak bones, cramps.
- Iodine — iodised salt, sea fish. Needed by the thyroid. Deficiency goitre, and cretinism in children.
- Iron — green leafy vegetables, jaggery, dates, liver, pulses. Makes haemoglobin. Deficiency anaemia.
- Sodium — common salt. Water and salt balance, nerve impulses, muscle contraction. Deficiency cramps and low blood pressure; excess raises blood pressure.
- Vitamin D is made by the body from sunlight, and calcium cannot be absorbed without it — so rickets can occur on a calcium-rich diet with no sunlight.
- Balanced diet — all the nutrients plus roughage, in the right proportions and quantity, varying with age, sex, body size, occupation, climate and health.
- Roughage is cellulose, not digested at all. It adds bulk, holds water, stimulates peristalsis and prevents constipation — the one component valuable because it is not absorbed.
- Kwashiorkor — protein deficiency with adequate energy; children of one to three; oedema of face, feet and abdomen, pot belly, enlarged liver, thin discoloured hair, flaky skin, loss of appetite, anaemia, stunted growth.
- Marasmus — deficiency of protein AND energy; infants under one; extreme wasting, ribs visible, no oedema, loss of subcutaneous fat, skin in folds, aged face, persistent hunger.
- Oedema present in kwashiorkor and absent in marasmus is the distinguishing feature.
- Prevention — a balanced diet with cheap local protein (pulses, groundnut, soya, ragi, milk), continued breast-feeding, weaning onto protein not starch alone, cereal plus pulse together, immunisation, deworming, clean water and nutrition education.
Cover the vitamin list and name the deficiency disease of each in ten seconds — then say which two of them can be caused without any shortage of food at all.