Every year the NDA General Ability Test slips in two or three sure-shot questions on vitamins, minerals and balanced diet. These are pure memory-and-match marks — no calculation, no diagrams, just clear recall. This Cavalier guide turns the whole NCERT nutrition syllabus into neat tables, tricks and traps so you never lose these easy marks again.
Why Nutrition Is a Scoring Topic for NDA
Food is the fuel of the body. The branch of biology that studies how organisms obtain and use food is called nutrition. For the NDA exam, this topic is gold because the questions are factual, repetitive and easy to revise the night before. Unlike physics numericals, nutrition questions reward plain memory, so a single focused revision can lock in two to three guaranteed marks every attempt.
Examiners usually test four things: the name of a nutrient, its best source, the deficiency disease it causes, and its function in the body. If you build a clear mental table linking these four columns, you can answer almost any question instantly. Past papers show that deficiency-disease matching and the ‘richest source’ type are the two most repeated formats.
Humans follow what biologists call holozoic nutrition — we take in solid food, digest it inside the body, absorb the useful parts and throw out the waste. This is different from plants, which make their own food by photosynthesis (autotrophic nutrition). Knowing this basic vocabulary helps you tackle the occasional definition-based question too.
The six classes of nutrients are carbohydrates, proteins, fats, vitamins, minerals and water. Carbohydrates, proteins and fats are macronutrients (needed in large amounts); vitamins and minerals are micronutrients (needed in tiny amounts but absolutely vital). Water, though needed in large amounts, supplies no energy.
The Three Macronutrients
Macronutrients supply the body with energy and building material. You must know what each does and where it comes from.
Carbohydrates
The body's main and cheapest source of energy. One gram of carbohydrate gives about 4 kilocalories. Found in rice, wheat, potato, sugar and bread. Excess carbohydrate is stored as glycogen in the liver and muscles.
Proteins
The body-building nutrient, made of amino acids. Needed for growth, repair of tissues and making enzymes and hormones. Rich sources are pulses, milk, eggs, fish, meat and soybean. One gram gives about 4 kcal.
Fats
The most concentrated energy source — one gram gives about 9 kcal, more than double carbohydrates. Fats also store energy, cushion organs and carry the fat-soluble vitamins A, D, E and K. Sources include ghee, butter, oil and nuts. Fats are broadly of two types: saturated fats (mostly from animals, solid at room temperature) and unsaturated fats (mostly from plants, usually liquid oils and considered healthier).
Carbohydrates themselves come in simple and complex forms. Simple sugars like glucose and fructose give quick energy, while complex carbohydrates like starch release energy slowly. Glucose is the body’s ready fuel, which is why a fall in blood glucose makes you feel weak and tired.
Energy value: Carbohydrate = 4 kcal/g, Protein = 4 kcal/g, Fat = 9 kcal/g. This high fat value is a favourite NDA trap. The unit kilocalorie (kcal) is also called the ‘Calorie’ with a capital C on food labels.
Vitamins: The Tiny but Mighty Helpers
Vitamins are organic compounds needed in very small quantities for normal growth and metabolism. The body cannot make most of them, so they must come from food. The term ‘vitamin’ was coined by Casimir Funk in 1912.
Vitamins are divided into two groups based on what dissolves them:
- Fat-soluble vitamins: A, D, E and K. They dissolve in fat and can be stored in the body (mainly the liver). Easy memory: “A D E K”.
- Water-soluble vitamins: the B-complex group and vitamin C. They dissolve in water, are not stored and any excess is passed out in urine, so they must be eaten daily.
Students think all vitamins are stored. Only the fat-soluble (A, D, E, K) are stored. Water-soluble vitamins (B and C) are lost in urine, which is why their deficiencies appear quickly.
Fat-Soluble Vitamins (A, D, E, K)
Vitamin A (Retinol)
Keeps the eyes, skin and mucous membranes healthy. Deficiency causes night blindness and dry eyes (xerophthalmia). Sources: carrots, papaya, green leafy vegetables, milk and liver. The orange pigment beta-carotene in carrots is converted to vitamin A in the body.
Vitamin D (Calciferol)
Helps the body absorb calcium and build strong bones. It is special because our skin makes it in sunlight — hence the nickname “sunshine vitamin”. Deficiency causes rickets in children (bent legs) and osteomalacia in adults.
Vitamin E (Tocopherol)
An antioxidant that protects cells from damage and helps reproduction. Deficiency can cause sterility and muscle weakness, and in newborns it can damage red blood cells. Sources: vegetable oils, nuts, seeds and wheat germ.
Vitamin K (Phylloquinone)
Essential for blood clotting. It helps the liver make the proteins that stop bleeding. Deficiency leads to excessive bleeding because blood cannot clot properly. Sources: green leafy vegetables; it is also made by helpful bacteria living in our intestine, which is why severe deficiency is rare in healthy adults.
Link by function: A → eyes, D → bones, E → reproduction, K → clotting. Trick: “Klotting starts with K.”
Water-Soluble Vitamins (B-Complex and C)
These must be supplied daily because the body does not store them.
Vitamin B1 (Thiamine)
Deficiency causes beri-beri (weak nerves and muscles). Found in whole grains and pulses. Polished white rice loses most of its B1.
Vitamin B2 (Riboflavin)
Deficiency causes cracks at the corners of the mouth and tongue inflammation. Sources: milk, eggs and green vegetables.
Vitamin B3 (Niacin)
Deficiency causes pellagra, marked by the “3 Ds” — dermatitis, diarrhoea and dementia.
Vitamin B12 (Cobalamin)
The only vitamin containing the mineral cobalt. Deficiency causes pernicious anaemia. Found only in animal foods, so strict vegetarians may need supplements.
Vitamin C (Ascorbic Acid)
An antioxidant that builds connective tissue (collagen), helps wounds heal and boosts immunity. It also improves the absorption of iron from food. Deficiency causes scurvy — bleeding and swollen gums, loose teeth and slow healing. Vitamin C is easily destroyed by heat, so overcooking vegetables removes much of it. Best sources are citrus fruits (amla, orange, lemon, guava) and tomatoes.
Amla (Indian gooseberry) is one of the richest natural sources of vitamin C and is a repeated NDA answer.
Essential Minerals and Their Roles
Minerals are inorganic nutrients. Macro-minerals (calcium, phosphorus, sodium, potassium) are needed in larger amounts; trace minerals (iron, iodine, zinc) are needed in tiny amounts.
Calcium and Phosphorus
Build bones and teeth. Calcium also helps muscle contraction and blood clotting. Sources: milk and dairy products.
Iron
A core part of haemoglobin, which carries oxygen in blood. Deficiency causes anaemia (tiredness, pale skin). Sources: green leafy vegetables, jaggery and liver.
Iodine
Needed by the thyroid gland to make hormones. Deficiency causes goitre (swelling of the neck). This is why we use iodised salt.
Sodium and Potassium
Maintain water balance and help nerve signals and muscle contraction. Common salt (NaCl) is the main source of sodium, while bananas and many fruits supply potassium. Too much sodium is linked to high blood pressure, so a moderate salt intake is advised.
Fluorine and Zinc
Fluorine in tiny amounts strengthens teeth, but too much causes fluorosis (mottled teeth and bone problems). Zinc helps wound healing and immunity. These trace minerals show how even microscopic amounts can decide health.
Do not confuse iron deficiency (anaemia) with iodine deficiency (goitre). Iron → blood; Iodine → thyroid/neck swelling. Also remember calcium and phosphorus work together for bones.
Quick Deficiency Disease Chart
This is the single most asked area. Burn this list into memory.
- Vitamin A → Night blindness
- Vitamin B1 → Beri-beri
- Vitamin B3 → Pellagra
- Vitamin B12 → Pernicious anaemia
- Vitamin C → Scurvy
- Vitamin D → Rickets / Osteomalacia
- Vitamin K → Poor blood clotting
- Iron → Anaemia
- Iodine → Goitre
- Calcium → Weak bones and teeth
Memory trick for vitamin C: “Citrus prevents sCurvy.” And “D for bones gets Damaged without sun.”
Balanced Diet and Roughage
A balanced diet is one that contains all six nutrients — carbohydrates, proteins, fats, vitamins, minerals and water — in the correct proportions needed for good health.
It must also include roughage (dietary fibre). Fibre such as the cellulose in vegetables and whole grains is not digested by humans, but it adds bulk, holds water and helps the smooth movement of food, preventing constipation.
Water makes up about two-thirds of body weight and is needed for digestion, transport of nutrients, regulation of body temperature and removal of wastes through urine and sweat. We lose water every day, so it must be replaced regularly to avoid dehydration.
The exact amount of food a person needs depends on the Basal Metabolic Rate (BMR) — the energy the body uses at complete rest just to stay alive. Active people, growing children and pregnant women need more energy and nutrients than someone sitting at a desk. A balanced diet is therefore not the same for everyone; it changes with age, sex, climate and activity level.
Roughage gives no energy but is essential for healthy digestion. Cellulose is the main fibre; humans lack the enzyme to break it down.
Malnutrition: Kwashiorkor and Marasmus
Malnutrition means a diet that is unbalanced — either too little (undernutrition) or too much (overnutrition) of nutrients. Two protein-deficiency diseases are popular NDA targets.
- Kwashiorkor: caused by severe protein deficiency (enough calories but little protein). Seen in children with a swollen belly, thin limbs and stunted growth.
- Marasmus: caused by deficiency of both protein and calories (energy). The child becomes extremely thin and wasted with little body fat.
Overnutrition is also a form of malnutrition. Eating far more energy than the body burns leads to obesity, which raises the risk of diabetes and heart disease. So a healthy diet means the right amount — neither too little nor too much.
Kwashiorkor = protein deficiency. Marasmus = protein + energy deficiency. Both are diseases of children and signs of poor nutrition. A simple memory aid: ‘Kwashiorkor’ has a swollen belly, ‘Marasmus’ is thin and ‘merciless’.
Worked Example
A 100 g serving of food contains 20 g carbohydrate, 10 g protein and 5 g fat. Estimate the total energy it provides in kilocalories.
So the serving supplies about 165 kilocalories. Notice how just 5 g of fat (45 kcal) gives almost as much energy as 10 g of protein (40 kcal) — that is the high energy density of fat in action.
Previous-Year Style Practice
Try this NDA-pattern question before checking the answer.
Q. Which one of the following pairs is correctly matched? (a) Vitamin C — Rickets (b) Vitamin D — Scurvy (c) Vitamin A — Night blindness (d) Vitamin K — Beri-beri
Answer: (c) Vitamin A — Night blindness. Vitamin C deficiency causes scurvy, Vitamin D deficiency causes rickets, and beri-beri is caused by Vitamin B1 deficiency — so only option (c) is correctly matched.
In ‘correctly matched’ questions, eliminate the obviously wrong pairs first. Knowing just three deficiency diseases for sure is usually enough to reach the right answer.
Quick Revision
- Six nutrient classes: carbohydrate, protein, fat, vitamin, mineral, water.
- Energy: carbohydrate and protein = 4 kcal/g; fat = 9 kcal/g.
- Fat-soluble vitamins = A, D, E, K (stored); water-soluble = B-complex and C (not stored).
- Key deficiencies: A → night blindness, C → scurvy, D → rickets, B1 → beri-beri, K → poor clotting.
- Minerals: iron → anaemia, iodine → goitre, calcium → weak bones.
- Protein deficiency: kwashiorkor; protein + energy deficiency: marasmus.
- Balanced diet = all nutrients in right proportion + roughage (fibre) for digestion.
Frequently asked questions
Which vitamins are fat-soluble and why does it matter?
Vitamins A, D, E and K are fat-soluble and can be stored in the body, mainly the liver. Because they are stored, their deficiencies develop slowly, unlike water-soluble B and C vitamins which must be eaten daily.
What is the difference between rickets and scurvy?
Rickets is caused by Vitamin D deficiency and leads to soft, bent bones in children. Scurvy is caused by Vitamin C deficiency and causes bleeding, swollen gums and slow wound healing.
Why is iodised salt recommended?
Iodine is needed by the thyroid gland to make hormones. A lack of iodine causes goitre, a swelling of the neck, so common salt is fortified with iodine to prevent this deficiency.
What is the difference between kwashiorkor and marasmus?
Kwashiorkor results from severe protein deficiency despite adequate calories and shows a swollen belly. Marasmus results from a shortage of both protein and energy, producing an extremely thin, wasted child.
Does roughage provide any energy?
No. Roughage or dietary fibre such as cellulose is not digested by humans and gives no energy, but it adds bulk to food, aids smooth digestion and prevents constipation.
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