Health: The Ultimate Treasure

Ask most people whether they are healthy and they will apply one small test: am I ill right now? If there is no fever, no cough and no injury, the answer is yes. That test is far too narrow. A student can have no named illness at all and still be exhausted every afternoon, unable to concentrate in the last two periods, worried about marks, and eating so poorly that one ordinary infection puts them in bed for a week. None of that appears on a doctor's list of diseases, yet none of it is health either.

The World Health Organization (WHO) fixed this wider idea in one sentence in its constitution: "Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." Notice the three words it insists on. Physical means the body works well: you can run for a bus, carry your school bag, heal from a cut, and your organs do their jobs. Mental means the mind works well: you can think clearly, handle disappointment, feel steady most days and enjoy things. Social means your life with other people works: you have family and friends you can talk to, you are safe at home and in school, and you are not cut off or bullied. Weaken any one of the three and the other two soon start to slip. A student who is being bullied stops sleeping; a student who never sleeps stops learning and falls ill more often.

Health is also not only a personal matter. Whether you stay well depends heavily on things one family cannot fix alone: is the water supply safe, is the drain outside covered, is garbage lifted, is the air thick with smoke and dust, is there a health centre within reach, can the family afford dal and vegetables every day? This is why we separate personal health - sleep, food, exercise, hygiene, habits - from public health or community health, which is what a village, a town or a government arranges for everybody together: piped clean water, drains and sewers, vaccination drives, mosquito control, food safety rules and hospitals. A single family boiling its water is doing personal health; a whole locality getting a covered drain is public health, and the second protects far more people.

Two more words are worth getting right. A disease is a specific condition in which some part of the body stops working properly, usually with a known cause and recognisable signs, and usually with a name. Being unhealthy is broader: it includes the slow drift caused by too little sleep, too much screen time, no exercise and poor food, long before anything is diagnosed. Most of what decides your health across a lifetime is not dramatic. It is the boring, repeated, daily choices - what is on your plate, how many hours you sleep, whether you wash your hands, whether you move your body, and whether you have someone to talk to when you feel low.

Finally, health is not a prize you win once and keep for ever. It changes week by week, and it can be rebuilt. A student who has been sleeping at one in the morning and living on biscuits is not doomed; the same body responds within days to better sleep and better food. That is the most useful message of this chapter. Health is a treasure you add to with small deposits, not something you either have or do not have.

Food is not one substance. It is a mixture of nutrients, and each nutrient does a different job in the body. A balanced diet is a diet that supplies every nutrient in the right amount for that particular person - enough, but not too much. The nutrients are usually grouped as carbohydrates, fats, proteins, vitamins and minerals, and to these we add two more essentials that are not strictly nutrients but are just as necessary: dietary fibre (also called roughage) and water.

Carbohydrates are the body's main fuel. Rice, wheat, jowar, bajra, ragi, potato, sugar and jaggery are rich in them, and for most Indian families they supply the largest share of the day's energy. Fats are fuel too, but far more concentrated - gram for gram they give more than twice the energy of carbohydrates, which is why fried food adds up so quickly. Ghee, oils, butter, nuts and seeds supply fat, and a certain amount of fat is genuinely needed, partly because vitamins A, D, E and K can be absorbed only when some fat is present in the meal. Carbohydrates and fats together are called energy-giving foods.

Proteins are the body-building foods. They are used to grow new tissue and to repair what is damaged, so a Class 8 student, whose body is still growing fast, needs them every single day. Dal, rajma, chana, soya, milk, curd, paneer, eggs, fish, chicken and groundnuts are good sources. Vegetarian meals cover protein well when a cereal and a pulse are eaten together, and the everyday Indian combinations of dal with rice, roti with chana, or idli with sambar are exactly that pairing.

Vitamins and minerals are needed in tiny quantities, yet the body cannot work without them, which is why they are called protective foods. Vitamins are labelled A, B (a whole group), C, D, E and K. Minerals include calcium, iron, iodine, phosphorus and potassium. Fruits, vegetables, milk and green leafy vegetables are the main suppliers. Dietary fibre comes from whole grains, pulses, vegetables and fruit with the skin on; it is not digested at all, but it gives the food inside the intestine bulk and keeps it moving, which prevents constipation. Water carries nutrients around the body, removes waste in urine and sweat, and keeps body temperature steady.

Balanced does not mean expensive. A thali of roti or rice, a bowl of dal, one seasonal vegetable, a little curd, a spoon of oil or ghee and a seasonal fruit covers every group at ordinary market prices. What people need differs from person to person: a growing teenager and someone doing heavy physical work need more energy than an adult sitting at a desk, and a person who is ill or pregnant has extra needs. Cooking matters as well. Vitamin C is easily destroyed by long cooking, vegetables should be washed before they are cut so that vitamins do not leach away into the water, and soaking and sprouting pulses makes them easier to digest.

The opposite problem is now as common as shortage. Packaged snacks, cold drinks, biscuits and deep fried food deliver plenty of energy with very little protein, vitamin, mineral or fibre - energy without nourishment. Eating them regularly can leave a person overweight and undernourished at the same time, which is exactly why a balanced diet is described as the right amount of everything rather than simply as enough food.

If a nutrient stays missing from the diet for a long time, the body cannot simply carry on without it. The particular job that nutrient did begins to fail, and the failure eventually shows up as a recognisable illness called a deficiency disease. These diseases are not caught from anybody. They build up slowly, from the plate, over months - which is also the reason that correcting the diet early can reverse many of them.

The best known examples come from the vitamins. Too little vitamin A causes night blindness, in which a person sees normally in bright light but cannot adjust in dim light; the eye also becomes dry, and a severe, long shortage can damage sight permanently. Carrot, papaya, mango, pumpkin, green leafy vegetables and milk prevent it. Too little vitamin B1 causes beriberi, with weak muscles and nerve problems; whole grains, pulses and groundnuts supply this vitamin, while heavily polished rice supplies very little of it. Too little vitamin C causes scurvy - bleeding, spongy gums, wounds that will not heal and aching joints; amla, guava, orange, lemon, tomato and green chilli are rich sources. Too little vitamin D causes rickets in children, in which growing bones stay soft and the legs may bend; the skin makes vitamin D when sunlight falls on it, and milk, egg yolk and fish also supply it.

The minerals produce their own set of diseases. A shortage of calcium leaves bones and teeth weak and easily broken; milk, curd, ragi, sesame seeds and green leafy vegetables are good sources, and vitamin D must be present for the body to absorb calcium properly, so a child kept permanently indoors can drink milk and still lose out. A shortage of iron causes anaemia: the blood carries less haemoglobin, so less oxygen reaches the tissues, and the person feels tired, gets breathless climbing stairs and looks pale. Anaemia is very common among Indian teenagers, and especially among girls. Green leafy vegetables, jaggery, dates and pulses help, and eating a source of vitamin C such as lemon in the same meal helps the body take up the iron. A shortage of iodine causes goitre, a swelling of the thyroid gland in the neck, and in young children it also slows growth and mental development. This is precisely why iodised salt is sold across the country: the cure costs almost nothing.

Shortage of protein and energy is more serious still, and it produces two recognised conditions in small children. Kwashiorkor follows a diet that is badly short of protein even while it still supplies some energy, and the child swells with fluid, most visibly in the feet and the face. Marasmus follows a severe shortage of energy and protein together, and the child wastes away to skin and bone. Both bring stunted growth and poor resistance to infection. A shortage of fibre, at the other end of the scale, simply causes constipation. One last point is worth stressing: being overweight is not the opposite of deficiency. A child who lives on biscuits, chips and cold drinks can be heavy and at the same time short of iron, calcium and several vitamins.

Diseases fall into two big families, and telling them apart is the single most useful idea in this chapter, because the two families are prevented in completely different ways.

A communicable disease, also called an infectious disease, is caused by a living organism that gets into the body and multiplies there. Such an organism is called a pathogen, or in everyday language a germ. There are four main kinds. Bacteria cause tuberculosis, typhoid and cholera. Viruses cause the common cold, influenza, measles, chickenpox, dengue, rabies and COVID-19. Protozoa, which are single-celled organisms, cause malaria and amoebic dysentery. Fungi cause skin infections such as ringworm and athlete's foot. Certain worms also live as parasites in the intestine.

What makes such a disease communicable is that the pathogen has some way of travelling to the next person. Those routes are worth learning as a list, because each one points to its own defence.

• Through air - tiny droplets thrown out when an infected person coughs, sneezes or talks are breathed in by someone nearby. Colds, influenza, tuberculosis, measles and COVID-19 travel this way.
• Through water - drinking water contaminated with sewage carries cholera, typhoid, hepatitis A and many diarrhoeal infections.
• Through food - food left uncovered, handled with unwashed hands or rinsed in unsafe water carries the same germs to the plate.
• By direct contact - touching an infected person, or sharing towels, combs and clothes, spreads ringworm and other skin infections.
• By vectors - an animal, usually an insect, carries the pathogen from one person to another. The female Anopheles mosquito carries the malaria parasite, and Aedes mosquitoes, which bite mainly in the daytime and breed in clean stored water, carry dengue and chikungunya.
• Through blood and body fluids - unsterilised needles and unscreened blood can pass hepatitis B and HIV, and rabies passes through the bite of an infected animal.

Read that list as a set of instructions rather than as information to memorise. Cover your mouth and keep the room ventilated against air-borne spread; boil or filter water against water-borne spread; wash hands and cover food against food-borne spread; do not share personal items against contact spread; and clear standing water and sleep under a net against mosquito-borne spread.

A non-communicable disease has no germ and therefore nothing to pass on. It develops inside one person's body over time and cannot be caught by sitting beside them. Diabetes, high blood pressure, heart disease, stroke, many cancers and asthma belong to this family, and so do all the deficiency diseases of the previous section. Their causes are a mixture: what a person eats over many years, how little they move, tobacco and alcohol, being overweight, long-running stress, polluted air, increasing age, and the tendencies a family passes down. Because they build slowly and silently, they often produce no symptoms for years, which is why adults are advised to have blood pressure and blood sugar checked even while they feel perfectly fine.

A simple test separates the two families. Ask whether a healthy person could get this disease from an infected person, either directly or through air, water, food or an insect. If the answer is yes, it is communicable. If the disease grew out of that one body's diet, habits, surroundings or inheritance, it is non-communicable. Nobody catches diabetes from a friend, and no amount of exercise makes a person immune to malaria.

Once you know how germs travel, prevention stops being a list to learn and becomes a set of habits that make sense. Hygiene means the practices that keep a person and their immediate surroundings clean. Sanitation means the arrangements a community makes to dispose of human waste, waste water and garbage safely. Hygiene is mostly what you do; sanitation is mostly what is built and maintained.

Handwashing deserves its reputation as the cheapest medicine ever invented. Hands touch door handles, money, phones, taps, railings and other people, and then touch food and the face. Soap works because its molecules can grip greasy dirt at one end and water at the other, lifting the oily film and the germs stuck in it off the skin so that running water carries them away; plain water alone slides over grease and leaves it there. Rub for about twenty seconds, covering palms, the backs of the hands, between the fingers, around the thumbs and under the nails, and wash before eating or cooking, after using the toilet, after handling waste or animals and after coughing or sneezing. This one habit alone brings down both diarrhoeal and respiratory infections.

Personal hygiene goes further: a daily bath, clean clothes, nails kept short and clean, teeth brushed twice a day, and no sharing of towels, combs, razors or handkerchiefs. Food hygiene matters just as much. Keep food covered so that flies cannot land on it, wash fruit and vegetables in safe water, cook food thoroughly, avoid keeping cooked food for long in warm weather, and prefer vendors who keep their stall, their water and their utensils clean. A fly that walks on an open drain and then on an uncovered plate is a complete route of infection in one short journey.

Sanitation is the community half of the same job. Human waste must go into a proper toilet connected to a septic tank or a sewer and never onto open ground, because the first rain then washes it into the water supply. Drains should be covered and flowing rather than open and stagnant. Household waste should be separated into wet and dry and lifted regularly, because a standing heap of garbage feeds flies, rats and stray animals. And every container of still water is a mosquito nursery - coolers, overhead tanks, buckets, flowerpot trays, discarded tyres, broken pots and coconut shells. Emptying, scrubbing or covering them once a week is the most effective single step a family can take against dengue.

That leaves safe drinking water. Water that looks perfectly clear can still be full of germs, so appearance and taste prove nothing at all. Several methods make water safe and they do different jobs, so it helps to know what each one can and cannot do. Boiling kills germs: bring the water to a rolling boil, keep it boiling for at least a minute, then let it cool in a covered vessel. Filtration through a candle filter, a ceramic filter or a clean folded cloth removes dirt and larger organisms, but a cloth by itself does not remove most bacteria and viruses. Chlorination, using chlorine tablets or bleaching powder in the correct dose, kills germs but does not clear mud. Muddy water must therefore be filtered first and chlorinated afterwards, because the dirt uses up much of the chlorine and germs sheltering inside the specks of dirt are shielded from it, so the same dose does far less work. Household RO and UV units are modern options where there is a reliable power supply. Whichever method is used, store the treated water in a covered container and take it out with a tap or a long-handled ladle rather than dipping in a hand or a glass, or the germs go straight back into water that had already been made safe.

Germs land on us constantly and most of the time nothing at all happens, because the body defends itself. That ability to resist disease is called immunity, and it works in layers.

The first layer keeps germs out altogether and never needs to know which germ it is facing. Unbroken skin is a wall that most pathogens cannot cross. Hair and mucus in the nose trap dust and germs, and a sneeze throws them back out. Tears and saliva contain substances that damage bacteria. Strong acid in the stomach destroys most of what is swallowed. Useful bacteria living in the intestine crowd out harmful ones. This layer is described as non-specific: it is present from birth and it treats every invader alike.

If a germ gets past that wall, the second layer takes over. White blood cells patrol the blood. Some of them surround and swallow germs outright, and they will do that to any invader they meet, so that part of the defence is still non-specific. Other white cells make antibodies - proteins shaped to lock onto one particular germ and mark it for destruction - and this part is specific, which has an important consequence: the antibody made against measles is of no use whatever against typhoid. Fever and swelling belong to the same fight rather than being separate illnesses; a fever is the body raising its own temperature to make conditions harder for the invader.

The remarkable part is what happens after the fight is won. The body keeps memory cells that remember that particular germ. If the same germ arrives again, antibodies appear so quickly and in such numbers that the person may never feel ill at all. This is why a child who has had chickenpox usually does not get it a second time, and it is the entire idea behind vaccination.

A vaccine gives the body that memory without making it suffer the disease first. It contains a germ that has been killed or weakened, or only a harmless piece of one, or instructions for the body to make such a piece itself. The immune system responds as though to a real attack, produces antibodies and memory cells, and is then ready in advance. The practice began in the late 1700s, when Edward Jenner showed that people who had caught the mild disease cowpox were protected against deadly smallpox. Vaccination eventually removed smallpox from the earth altogether; the World Health Organization declared it eradicated in 1980, and it remains the only human disease ever wiped out in this way. India was certified polio-free in 2014 after many years of pulse polio campaigns.

In India a set of vaccines is given free at government hospitals and health centres from birth through childhood, including BCG against tuberculosis, drops against polio, and vaccines against diphtheria, whooping cough, tetanus, hepatitis B, measles and rubella. Some of them need booster doses because protection weakens with time. Vaccination also protects people who are not vaccinated: when most of a community is immune, a germ arriving in the area finds too few people to move through and dies out, which shields newborn babies and those too ill to be vaccinated. That is why a vaccination drive is treated as a public-health measure and not merely as a private choice.

One warning belongs here. Antibiotics are medicines that kill bacteria. They do nothing at all against viruses, so taking them for an ordinary cold is useless. Take them only when a doctor prescribes them, and finish the whole course even after you feel better, because stopping early leaves the toughest bacteria alive to multiply, and that is how bacteria become resistant to medicines that once worked perfectly well.

Food, hygiene and vaccines protect you from specific dangers. Three further habits decide how well you actually live from day to day: how much you move, how much you sleep, and how you look after your mind. They are the easiest parts of health to neglect, because neglecting them causes no immediate pain.

Physical activity is not the same thing as sport, and you do not need a ground or equipment. Walking, cycling, climbing stairs, kho-kho, kabaddi, football, skipping, dancing and helping with housework all count. Children and teenagers are generally advised to get about an hour a day of activity that leaves them breathing harder than usual. Regular movement strengthens the heart and lungs, builds muscle and bone while the body is still growing, keeps weight in a healthy range, improves sleep, and lowers the lifelong risk of diabetes and heart disease. It also works directly on mood, and is one of the most reliable ways of reducing worry and restlessness. The opposite habit, sitting for hours without a break, works against all of that on its own, so the answer is not only an hour of games but also standing up and moving between study sessions, and resting the eyes from screens by looking at something at least six metres away for about twenty seconds every twenty minutes or so.

Sleep is not lost time. While you sleep, the body repairs tissue, releases the hormones that drive growth, strengthens the immune system, and - most usefully for a student - moves the day's learning into longer-term memory. Students of Class 8 age generally need somewhere around eight to ten hours a night, and a great many get considerably less. The results of short sleep are easy to recognise: dozing in class, irritability, poor concentration, careless mistakes, falling ill more often, and a noticeably stronger pull towards sugary and fried food. Going to bed at roughly the same time each night, keeping the room dark and quiet, and putting the phone away well before bed all help, because bright screens and exciting content late at night make it harder to fall asleep. Studying until two in the morning before a test is a poor trade, because the hours of sleep given up are exactly the hours in which the material just revised would have been fixed into memory.

Mental wellbeing is the part most often ignored, and it belongs in a health chapter just as much as diet does. Feeling nervous before an exam, sad after a quarrel or angry at unfairness is completely normal, and those feelings pass. It is a different matter when low mood, fear or hopelessness continues for weeks, when a student stops enjoying anything at all, cannot sleep or eat, pulls away from friends, or has thoughts of harming themselves. Those are signs of a health problem, exactly as a continuing fever would be, and they call for help rather than shame or silence. Talking to a parent, a teacher or a school counsellor is a real step and not a weakness, and free government tele-counselling helplines exist in India for anyone who would rather speak to someone outside their own circle. Ordinary measures genuinely help too: a steady routine, time outdoors, exercise, staying in contact with friends in person, limiting the hours spent comparing your life with edited versions of other people's lives online, and asking for help early rather than late.

Tobacco, alcohol and other drugs deserve one plain line. Every one of them damages health, every one of them is addictive, and almost every one of them is first tried because a friend offered it and refusing felt awkward. The genuinely useful skill to build at this age is saying no without embarrassment.