Vitamins, Nutrition and Diseases Notes

Food gives us energy, helps us grow and protects us from disease. Questions on nutrition, vitamins, minerals and deficiency diseases are among the most predictable questions of the general science section in SSC, railways, banking, defence, state-level examinations and the UPSC Prelims. This note explains the nutrients and their functions, the vitamins with sources and deficiency diseases in a table, important minerals, a classification of common diseases by cause, and the basics of a balanced diet and malnutrition in India, in simple language.

Nutrients: What Food Gives Us

The food we eat contains six groups of nutrients. Carbohydrates (rice, wheat, potato, sugar) give quick energy; 1 gram gives about 4 kilocalories. Proteins (pulses, milk, eggs, fish, meat, soya) are the body-building nutrients that repair cells; 1 gram gives about 4 kilocalories. Fats (oils, ghee, butter, nuts) give concentrated energy of about 9 kilocalories per gram and help in absorbing fat-soluble vitamins. Vitamins and minerals are needed in small quantities to regulate body processes and protect from disease. Water makes up about 60 to 70 percent of body weight and is needed for all processes. Dietary fibre (roughage) from vegetables, fruits and whole grains is not digested but helps in bowel movement and prevents constipation. A balanced diet has all these in the right amounts. An adult needs roughly 2,000 to 2,700 kilocalories a day, depending on age, gender and the type of work.

Vitamins: Sources and Deficiency Diseases

Vitamins are organic compounds that the body needs in small amounts but cannot make in enough quantity (except vitamin D with sunlight, vitamin K and some B vitamins by gut bacteria). They are of two types: fat-soluble (A, D, E and K), which are stored in the body, and water-soluble (B-complex and C), which are not stored and must be taken regularly.

A simple way to remember: "A for eyes, B for nerves and energy, C for gums, D for bones, E for fertility and K for clotting". Vitamin D is called the sunshine vitamin because the skin makes it in sunlight. Vitamin C is easily destroyed by heat, so overcooking vegetables reduces it. Vitamin B12 is the only vitamin that contains a metal (cobalt), and strict vegetarians may need supplements or fortified foods. Vitamin A deficiency is the leading cause of preventable childhood blindness, so India runs a vitamin A supplementation programme.

Important Minerals

Protein-Energy Malnutrition

When a child's diet lacks protein or energy, two conditions occur. Kwashiorkor is due to protein deficiency, even if the energy intake is adequate, and the child shows swollen legs and face, thin hair and a swollen belly. Marasmus is due to a lack of both protein and energy, and the child is very thin, with wrinkled skin and no fat. Malnutrition is a serious problem in India. Government programmes such as Integrated Child Development Services (ICDS) through anganwadis, PM POSHAN (the mid-day meal scheme), Poshan Abhiyaan and the National Food Security Act, 2013 aim to reduce undernutrition. Food fortification means adding nutrients such as iron, iodine and vitamins to staple foods, as in iodised salt and fortified rice. The Food Safety and Standards Authority of India (FSSAI) regulates food standards.

Body Mass Index and Obesity

Body Mass Index (BMI) is weight in kilograms divided by the square of height in metres. For a person weighing 70 kg with a height of 1.75 m, BMI = 70/(1.75 × 1.75) = 70/3.0625, which is about 22.9, in the normal range. A BMI below 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight and 30 or above is obese. Obesity increases the risk of diabetes, high blood pressure and heart disease. A balanced diet, regular exercise, enough sleep and limited sugar and junk food help to prevent these lifestyle diseases.

Classification of Diseases by Cause

Some genetic disorders are worth remembering. Haemophilia (the blood does not clot properly) and colour blindness are X-linked recessive disorders, which are more common in males. Down syndrome is caused by an extra copy of chromosome 21 (trisomy 21). Turner syndrome (XO) affects females, and Klinefelter syndrome (XXY) affects males. Sickle cell anaemia and thalassaemia affect haemoglobin. Albinism is the lack of pigment. Diabetes mellitus arises from a lack or poor action of insulin. Cancer is the uncontrolled division of cells.

Prevention of Diseases

Prevention is better than cure. Good hygiene, clean drinking water, proper sanitation, safe food handling and control of mosquitoes prevent many infectious diseases. Vaccination protects against polio, measles, hepatitis B, tetanus and many others. A balanced diet prevents deficiency diseases. Regular exercise, avoiding tobacco and alcohol, and routine health check-ups reduce lifestyle diseases. Public programmes such as the Universal Immunisation Programme, Swachh Bharat Mission and Ayushman Bharat support prevention.

A Balanced Diet for an Indian Student

A balanced diet is not costly; it is about variety. A plate should contain cereals such as rice, roti or millets for energy, pulses or eggs or milk products for protein, a generous amount of vegetables and fruits for vitamins, minerals and fibre, and a small quantity of oil or nuts for healthy fats. Include green leafy vegetables for iron and folic acid, curd for calcium and probiotics, and seasonal fruits such as guava, amla or papaya for vitamin C. Drink enough water, about 2 to 3 litres a day, and limit sugar, salt and fried snacks. Skipping breakfast, relying on junk food and sleeping late affect concentration, so serious aspirants should plan regular meals. The traditional Indian thali, with several small dishes, already follows the principle of a balanced diet.

Cooking and Storage Tips That Save Nutrients

How food is prepared affects its nutrition. Washing vegetables after cutting, cooking them in a lot of water and throwing the water away, and overcooking all destroy water-soluble vitamins such as B and C. Steaming, pressure cooking for a short time and eating raw salads preserve them. Sprouting pulses increases vitamin C and makes minerals easier to absorb. Fermented foods like idli, dosa and dhokla add B vitamins and are easier to digest. Parboiled rice retains more vitamins than highly polished rice, which is why polishing was linked with beriberi in the past. Storing oils away from light and heat protects vitamin E. These small habits protect health at almost no cost.

Quick Revision

• Vitamin A: night blindness; B1: beriberi; C: scurvy; D: rickets; K: poor clotting; B12: pernicious anaemia.
• Iron: anaemia; iodine: goitre; calcium: rickets and osteoporosis.
• Fat gives 9 kcal per gram; carbohydrates and proteins give 4 kcal per gram.
• Kwashiorkor is protein deficiency; marasmus is protein and energy deficiency.

Make a chart of vitamins, minerals and diseases, and revise it every week. Link each deficiency with a food you eat daily and, with this approach, these questions will become quick and sure marks.

Related Notes to Read Next

Continue your preparation with these related notes from the same subject:

• Everyday Science Notes for Competitive Exams
• Cell Biology, Genetics and Plant Science Notes for Competitive
• Atomic Structure, Carbon Compounds and Fuels Notes
• All General Science notes

Frequently Asked Questions (FAQ)

Which vitamin deficiency causes night blindness?

Deficiency of vitamin A causes night blindness and, in severe cases, xerophthalmia.

Which disease is caused by vitamin C deficiency?

Deficiency of vitamin C causes scurvy, with bleeding gums and slow healing of wounds.

Which vitamin is called the sunshine vitamin?

Vitamin D is called the sunshine vitamin because the skin makes it when exposed to sunlight.

What is the disease caused by vitamin D deficiency?

Deficiency of vitamin D causes rickets in children and osteomalacia in adults.

Which vitamin is needed for blood clotting?

Vitamin K is needed for the clotting of blood.

Which vitamin contains cobalt?

Vitamin B12 (cobalamin) contains the metal cobalt.

What causes goitre?

Goitre is caused by iodine deficiency, which affects the production of thyroxine by the thyroid gland.

What is the difference between kwashiorkor and marasmus?

Kwashiorkor is caused by protein deficiency, while marasmus is caused by deficiency of both protein and energy.

How many kilocalories does 1 gram of fat give?

One gram of fat gives about 9 kilocalories, while carbohydrates and proteins give about 4 kilocalories per gram.

What is BMI and how is it calculated?

Body Mass Index is weight in kilograms divided by the square of height in metres. A BMI of 18.5 to 24.9 is considered normal.

Which disease is caused by an extra chromosome 21?

Down syndrome is caused by an extra copy of chromosome 21.

What is food fortification?

Food fortification means adding essential nutrients such as iron, iodine or vitamins to commonly eaten foods like salt and rice to prevent deficiencies.