Vitamins, Minerals & Deficiency Diseases – NDA Biology Notes

Your body is like a factory. It needs raw materials to build things. It needs fuel to run machines. But it also needs workers, small substances that make every process happen correctly. Vitamins and minerals are those workers.

Without energy sources like carbohydrates and fats, the factory shuts down. But without vitamins and minerals, the factory makes mistakes. Bones form incorrectly. Blood does not clot. Nerves stop signalling. Eyes fail in the dark.

Vitamins are organic compounds produced by living things. Minerals are inorganic elements that come from soil and water. Both are needed in tiny amounts, but their absence causes diseases that are specific, predictable, and preventable. For the NDA exam, this chapter is precision territory: every question targets a specific deficiency, a specific chemical name, or a specific function. Every section below marks exactly where exam questions originate.

1. What are Vitamins and Minerals?

Vitamins are organic compounds that the body needs in small amounts but cannot manufacture in sufficient quantities on its own (with one important exception, Vitamin D, which skin can produce in sunlight). Minerals are inorganic elements that must come entirely from food and water.

Both vitamins and minerals are classified as micronutrients: they are needed in much smaller quantities than the macronutrients (carbohydrates, proteins, fats). But their absence causes deficiency diseases that are as serious as any macronutrient shortage.

2. Balanced Diet: The Complete Picture

A complete, balanced diet has seven components: carbohydrates, proteins, fats, vitamins, minerals, dietary fibre, and water. No single component is optional. All seven are collectively necessary for sustaining life and health.  [NDA 2010-III]

NDA 2024 asked which combination most completely represents a balanced diet. Options that left out fibre or water were wrong. The correct answer included all seven.  [NDA 2024-II]

Students sometimes treat vitamins and minerals as extras, supplements for the already healthy. That is wrong. They are core components of the diet, as fundamental as carbohydrates and proteins.

For vegetarians, vegetables and fruits are the main combined source of both vitamins and minerals. Dietary variety within plant foods is therefore especially important.  [NDA 2021-I]

3. Fat-Soluble and Water-Soluble Vitamins

Not all vitamins behave the same way inside the body. The most important division is by how they dissolve, and this division has direct consequences for storage, toxicity, and excretion.

Category	Vitamins	Behaviour in Body	Exam Consequence
Fat-soluble	A, D, E, K	Stored in body fat and liver; not excreted in urine; accumulate over time: excess can cause toxicity	When asked which vitamins are stored (not excreted): A, D, E, K
Water-soluble	B-group (B₁, B₂, B₃, B₆, B₇, B₉, B₁₂) and C	Excess filtered by kidneys and excreted in urine; do not accumulate; must be consumed regularly	When asked which vitamins are excreted in urine: B-group and C

The practical consequence: fat-soluble vitamins can build up to toxic levels if taken in excess over long periods. Water-soluble vitamins are safer in this regard. The kidneys eliminate any surplus.

4. Chemical Names: The Matching Table

NDA asks vitamin chemical names repeatedly in match-the-following format. The complete set must be memorised as a unit. Each name below has been tested in the year shown.

Vitamin	Chemical Name	Deficiency Disease
Vitamin A	Retinol	Night blindness
Vitamin B₁	Thiamine	Beriberi [NDA 2025-I]
Vitamin B₂	Riboflavin	Ariboflavinosis (cracked lips, inflamed tongue)
Vitamin B₃	Niacin	Pellagra (Dermatitis, Diarrhoea, Dementia)
Vitamin B₉	Folic acid	Neural tube defects
Vitamin B₁₂	Cobalamin	Pernicious anaemia
Vitamin C	Ascorbic acid	Scurvy
Vitamin D	Calciferol	Rickets (children); Osteomalacia (adults)
Vitamin E	Tocopherol	Rare : antioxidant role
Vitamin K	Phylloquinone	Excessive bleeding; impaired blood clotting

★ IMPORTANT Vitamin B₁₂ (Cobalamin) is the only vitamin that contains a metal ion, cobalt, in the +3-oxidation state (Co³⁺). No other vitamin has a metal at its core. Vitamin C = Ascorbic acid: not methanoic acid, not lactic acid, not tartaric acid. These wrong chemical names appear as distractor options.

5. Vitamin A (Retinol)

β-Carotene: The Pro-Vitamin

The body cannot make Vitamin A from nothing. It needs a starting material called β-carotene; the orange-yellow pigment found in carrots, mangoes, papaya, and dark leafy vegetables. When the body needs Vitamin A, it converts β-carotene into Retinol in the intestinal wall and liver. For this reason, β-carotene is called a pro-vitamin. It is the raw material the body uses to build the actual vitamin.  [NDA 2015-II]

Vision: Rhodopsin and Night Blindness

The retina at the back of the eye contains two types of light-detecting cells: rod cells and cone cells. Rod cells work in dim light and darkness. They contain a pigment called rhodopsin. Rhodopsin is what allows rod cells to detect low levels of light. Rhodopsin can only be made when Vitamin A is present. No Vitamin A means no rhodopsin. No rhodopsin means rod cells stop working in dim light. The result is night blindness, the inability to see clearly after dark or in a poorly lit room.

Vitamin A deficiency causes night blindness, not rickets. Rickets is caused by Vitamin D deficiency. This is the most confused pair in this chapter.

Vitamin A also maintains healthy skin and mucous membranes, the moist linings of the nose, throat, and digestive tract. These membranes are the body’s first line of defence against infection.

Sources and What Is NOT a Source

Vitamin A comes from animal sources: liver, egg yolk, and fish liver oil. β-carotene from plant sources, such as carrots, spinach, and mango, is converted into Vitamin A inside the body. Milk is not a rich source of Vitamin A. Milk’s nutritional strength lies in calcium and protein, not Vitamin A.

Golden Rice

In many developing countries, populations rely almost entirely on white rice. White rice contains virtually no Vitamin A or β-carotene, leading to widespread deficiency. Golden Rice was developed as a solution: scientists genetically engineered rice to produce β-carotene, which gives the grains their golden colour. When eaten, the body converts this β-carotene into Vitamin A.

Golden Rice is enriched with β-carotene and iron. It does not contain Vitamin A directly. It is not enriched with niacin or folic acid. These are common wrong options in the exam.

6. Vitamin D (Calciferol)

How the Body Makes Vitamin D

Vitamin D is unusual among vitamins. The body can manufacture it internally, but only with the help of sunlight. When ultraviolet (UV) radiation from sunlight falls on the skin, a chemical reaction converts a cholesterol compound in the skin into Vitamin D.

This is why sunlight is the primary source of Vitamin D for humans. Citrus fruits do not provide Vitamin D. Green vegetables do not provide Vitamin D. Yeast does not provide meaningful Vitamin D.  [NDA 2015-II] People who spend very little time outdoors are at higher risk of deficiency.

The Calcium Connection

Vitamin D’s main role is enabling calcium absorption from food in the intestine. Think of Vitamin D as a key that unlocks the door to calcium absorption. Without the key, calcium cannot enter, no matter how much of it is present in the diet. A person can eat calcium-rich food every day and still develop weak bones if Vitamin D is absent.

Deficiency Diseases

Population	Condition	What Happens
Children	Rickets [NDA 2024-II]	Bones remain soft and bend under body weight: bow legs, chest deformity, skull softening
Adults	Osteomalacia	Bones soften and ache; fracture more easily: without the bowing seen in children

Rickets is caused exclusively by Vitamin D deficiency, not Vitamin A, not Vitamin C, not Vitamin B deficiency. Only Vitamin D.  [NDA 2024-II]

Calcium in Space

Astronauts on long space missions experience significant calcium loss through urine. Bones weaken even though they eat well. The reason is microgravity, not diet or temperature.  On Earth, the mechanical stress of standing and walking signals bones to retain calcium. In space, there is no gravity, no mechanical stress, and bones begin releasing calcium. Bone health depends on both adequate nutrition and physical loading. Neither alone is enough.

7. Vitamin K

When the body is injured, blood must clot quickly. Clotting is a chain reaction involving many proteins called clotting factors. Each factor activates the next. Eventually, fibrin forms a mesh that traps blood cells and seals the wound.

Vitamin K is essential for making several of these clotting factors active. It activates them by a chemical modification called carboxylation. Without Vitamin K, the clotting factors remain inactive. The chain reaction cannot start. Blood does not clot. A person with Vitamin K deficiency will bleed excessively from even a small wound.

★ IMPORTANT Vitamin K = blood clotting: no other vitamin does this. Vitamin K has been tested many times in NDA exams: [NDA 2012-II | NDA 2017-II] This is the single most tested vitamin-function fact in the chapter. Every student must know it. Vitamin A does not clot blood. Vitamin C does not clot blood. Vitamin D does not clot blood. Only Vitamin K.

8. Vitamin C (Ascorbic Acid)

Collagen Production

Vitamin C is Ascorbic acid. Its most important role is the production of collagen, the most abundant protein in the human body. Collagen forms the structural framework of skin, gums, blood vessel walls, tendons, and connective tissue. Think of collagen as the body’s scaffolding. It holds everything together. Without Vitamin C, the enzymes that build collagen cannot work. Collagen production slows and then stops.

Scurvy: Vitamin C Deficiency

The result of severe Vitamin C deficiency is Scurvy. Without collagen, blood vessel walls weaken and leak blood into surrounding tissue. The gums swell and bleed. Teeth become loose. Wounds refuse to close or reopen. Joints ache. Skin bruises at the slightest touch.  [NDA 2019-II]

Scurvy was historically devastating among sailors on long voyages, months without fresh fruits or vegetables. The discovery that citrus fruit prevented scurvy was one of the most important medical advances of its time.

Sources: Guava Tops the List

Most people associate Vitamin C with lemon and orange. Those are good sources. But guava is exceptionally rich in Vitamin C, richer per 100 grams than most citrus fruits. This surprises students and appears as a direct exam question.

Milk is a poor source of Vitamin C. Fruits and vegetables are the dominant sources.  [NDA 2009-I]

9. Vitamin B Group

The B vitamins are a family of eight water-soluble vitamins. They share the B label but have different structures, different functions, and different deficiency diseases. Three are tested directly and repeatedly.

Vitamin B₁: Thiamine and Beriberi

Vitamin B₁ is Thiamine. It plays a central role in converting carbohydrates into energy the body can use. Without Thiamine, cells, especially in the nervous system and heart, cannot extract energy from glucose efficiently.  [NDA 2008-II | NDA 2025-I]

The deficiency disease is Beriberi. In one form, the nervous system is primarily affected: weakness, numbness, and difficulty walking. In another form, the heart is affected. It enlarges and fluid accumulates in the body.

Beriberi was historically common in parts of Asia where polished white rice was the dietary staple. The milling process that produces white rice removes the outer bran layer, and that bran layer is where thiamine is concentrated.

Vitamin B₉: Folic Acid and Pregnancy

Folic acid is essential for DNA synthesis, copying and creating genetic material during cell division. This makes it critically important during the first trimester of pregnancy. In the first weeks after conception, the neural tube forms in the embryo. This structure later develops into the brain and spinal cord. This process requires rapid, accurate cell division. If folic acid is insufficient, the neural tube does not close properly, causing serious birth defects.

Green leafy vegetables are the principal dietary source of folic acid, which is why medical guidance specifically recommends increased consumption of green leafy vegetables during early pregnancy.

Iron combined with folic acid tablets specifically signals the treatment of iron-deficiency anaemia. This combination distinguishes anaemia treatment from osteoporosis (calcium), goitre (iodine), and protein-energy malnutrition (protein).  [NDA 2014-II]

Vitamin B₁₂: Cobalamin and Pernicious Anaemia

Vitamin B₁₂ is needed for the formation of healthy red blood cells and the maintenance of the protective sheath around nerve fibres. When B₁₂ is deficient, red blood cells become abnormally large and cannot function properly. The result is pernicious anaemia, distinct from iron-deficiency anaemia, which produces small, pale cells.

Vitamin B₁₂ is structurally unique. It contains a cobalt ion (Co³⁺) at the centre of its complex ring structure: the only vitamin in existence that contains a metal ion. No other vitamin has a metal at its core.

Other B Vitamins: Brief Coverage

Vitamin B₂ (Riboflavin) deficiency causes Ariboflavinosis, painful cracks at the corners of the mouth and inflammation of the tongue.

Vitamin B₃ (Niacin) deficiency causes Pellagra, remembered by the three Ds : Dermatitis (skin rash in sun-exposed areas), Diarrhoea (gut symptoms), and Dementia (confusion and memory loss).

Vitamins B₆ (Pyridoxine) and B₇ (Biotin) deficiencies are rare and have not been directly tested as primary knowledge questions in NDA.

10. Minerals

Minerals are inorganic elements the body cannot synthesise. They must come entirely from food and water. Unlike vitamins, which the body can sometimes produce internally, as with Vitamin D from sunlight, minerals must always come from outside.

Minerals serve structural roles (building bones and teeth), regulatory roles (controlling nerve signals, muscle contractions, and enzyme functions), and transport roles (iron in haemoglobin carries oxygen).

11. Iodine

The Thyroid Gland and Thyroxin

The thyroid gland sits at the front of the neck. Its job is to produce thyroxin, a hormone that regulates the body’s metabolic rate, controlling how fast the body burns energy, how active organs are, and how quickly growth and development proceed.

To make thyroxin, the thyroid gland needs iodine. It actively absorbs iodine from the blood and uses it as a raw material in thyroxin synthesis. The thyroid gland is the only place in the body that uses iodine.

Most people get their iodine from iodised salt; regular table salt fortified with a small amount of iodine. This is the primary dietary vehicle for iodine in India.  [NDA 2025-I]

Goitre: When Iodine Is Insufficient

When iodine is absent, the thyroid cannot make thyroxin. The brain detects low thyroxin levels and sends signals telling the thyroid to work harder. The thyroid responds by growing, enlarging to try to capture more iodine from the blood. This visible swelling at the front of the neck is called Goitre. Goitre is not a disease of the thyroid itself. It is the thyroid’s response to an inadequate iodine supply.  [NDA 2015-I]

Iodine’s role is limited to thyroxin production in the thyroid. It does not produce adrenaline. Adrenaline is made by the adrenal gland. Iodine has no connection to the pancreas and no role in cholesterol regulation. These wrong associations appear as distractor options.

12. Iron

Every red blood cell contains millions of molecules of haemoglobin, the protein that carries oxygen from the lungs to every cell. At the centre of each haemoglobin molecule is an iron atom that binds to oxygen. Without iron, haemoglobin cannot be made. Without haemoglobin, oxygen cannot be transported.

When iron is insufficient, the body cannot make enough functioning haemoglobin. Red blood cells become small and pale. They carry less oxygen. Every cell receives less oxygen than it needs. The result is iron-deficiency anaemia: persistent fatigue, breathlessness, pale skin, and difficulty concentrating.  

Iron-deficiency anaemia is the most common nutritional deficiency in India, particularly among women and young children. Women lose iron through menstruation. Children need extra iron during growth. Spinach (palak) is a well-recognised plant-based source of iron.

Iron-deficiency anaemia is treated with iron and folic acid tablets together. This combination distinguishes it from osteoporosis (calcium), goitre (iodine), and protein-energy malnutrition (protein).  [NDA 2014-II]

13. Calcium and Phosphorus

Calcium and phosphorus together form calcium phosphate, the mineral compound that gives bones and teeth their hardness and structural strength.

Bones are a composite material: calcium phosphate crystals embedded in a framework of collagen protein. The mineral provides hardness. The collagen provides flexibility. Together they make bone strong without being brittle.

Tooth enamel is the hardest substance in the human body. It is composed almost entirely of calcium phosphate, not calcium carbonate, not calcium sulphate, not calcium hydroxide.  [NDA 2019-II]

When calcium intake is chronically insufficient, the body draws calcium from bones to maintain blood calcium levels. Over years, this gradually weakens the bone structure, a condition called osteoporosis. Milk and eggs are among the richest dietary sources of calcium.

The astronaut calcium loss phenomenon, weakening bones in space despite adequate diet, is due to microgravity, not nutrition. On Earth, mechanical stress from standing and walking signals bones to retain calcium. In space, this loading disappears, and calcium is lost.

14. Sodium and Potassium: Nerve Signalling

A nerve signal, called an action potential, is an electrical event created by ions moving across the nerve cell membrane. At rest, the inside of a nerve cell has a negative electrical charge relative to the outside. When a nerve fires:

• Sodium ions (Na⁺) rush into the cell through special channels: making the inside briefly positive (the signal)
• Potassium ions (K⁺) flow out: restoring the negative charge (resetting for the next signal)

Both sodium and potassium are essential to this process. Without sodium, the signal cannot be generated. Without potassium, it cannot be reset.

★ IMPORTANT Earlier NDA papers framed sodium alone as the key mineral for nerve signal transmission.  [NDA 2018-I] NDA 2022 refined the answer: both sodium AND potassium together enable nerve impulse transmission.  [NDA 2022-II] When both appear as an option, that is the correct and complete answer. Sodium alone is the outdated version.

15. Zinc and Fluoride

Zinc and Immunity

Zinc supports the immune system at multiple levels. It is needed for the development and function of immune cells, helps wounds heal, and supports the sense of taste and smell. Among all minerals, zinc deficiency is most directly associated with impaired immunity. A person deficient in zinc becomes more vulnerable to infections and heals more slowly from injuries.

Fluoride and Dental Health

Fluoride has a precise, dose-dependent relationship with dental health. In the correct small quantity, fluoride is incorporated into tooth enamel during its formation, making enamel harder and more resistant to acid attacks that cause tooth decay.

However, when fluoride intake is too high, it causes dental fluorosis. The enamel becomes mottled, pitted, and discoloured, appearing chalky white, brown, or streaked. The same mineral that strengthens teeth in small doses damages them in large doses.

16. Magnesium: Plant Macronutrient

Magnesium is the central metal atom of every chlorophyll molecule, the pigment that makes plants green and enables photosynthesis. This is directly analogous to iron sitting at the centre of haemoglobin in human blood.

Because chlorophyll is present in enormous quantities in green plants, plants need relatively large amounts of magnesium. This places it in the category of plant macronutrients, minerals required in larger quantities.

Students frequently place magnesium alongside iron and manganese as a plant micronutrient. That is incorrect. Iron, manganese, and chlorine are genuine plant micronutrients, needed only in trace amounts. Magnesium is in a different and higher-demand category entirely.

---