Health is a state of physical, mental, and social well-being. It involves more than just the absence of disease. A truly healthy person not only feels good physically but also has a realistic outlook on life and gets along well with other people. Good health enables people to enjoy life and have the opportunity to achieve the goals they have set for themselves.

To achieve and maintain good health, people must have basic knowledge about the human body and how it functions. Only then can they determine what will or will not help or damage their health. Therefore, learning about health should be a part of every person's education. Current knowledge about health, together with good living habits, can help almost everyone maintain good health and improve their quality of life.

Society as a whole benefits from people's good health just as individuals do. For that reason, many government and voluntary agencies strive to preserve and improve the health of all people. The World Health Organization (WHO), an agency of the United Nations, works to promote better health throughout the world.

Elements of physical health

All parts of the body must work together properly to maintain physical health. A person who is in good physical condition has the strength and energy to enjoy an active life and withstand the stresses of daily life. Proper nutrition, exercise, rest and sleep, cleanliness, and medical and dental care are all essential to healthy living.

Nutrition. A balanced diet provides all the food substances needed by the body for healthy growth and development. Nutritionists use the term nutrients for these substances and classify them into five main groups: (1) carbohydrates, (2) fats, (3) proteins, (4) vitamins, and (5) minerals. Water is also essential for life, but it is often considered separately from nutrients.

A balanced diet consists of a wide variety of foods. Fruit and vegetables provide important vitamins and minerals. Meat, poultry, fish, eggs, dairy products, and nuts are rich sources of protein. Bread, cereals, and potatoes furnish carbohydrates in addition to vitamins and minerals.

Good nutrition also includes eating the proper amount of food each day. Overeating can lead to obesity (fatness). Excess weight puts extra strain on the heart and increases a person's chances of getting such diseases as diabetes and heart disease. Many people try to lose weight quickly and easily by following one of the many widely advertised fad diets. But these diets can be dangerous, especially if used over a long period of time. The safest way to lose weight is to consult a doctor and follow the reducing programme he or she prescribes. Most programmes combine moderate daily exercise with a balanced diet that contains a limited number of calories.

Exercise helps keep the body healthy and fit. Vigorous exercise strengthens muscles and improves the function of the circulatory and respiratory systems. Physical fitness benefits both physical and mental health. It enables the body to withstand stresses that otherwise could cause physical and emotional problems.

To achieve fitness, a person should start an exercise programme slowly and build it up gradually to a level that maintains a healthy heart and strong muscles. Daily exercise provides the greatest benefits, and so it is important to choose exercises that can be performed every day. Such popular activities as bicycling, jogging, and swimming, and even taking long, brisk walks, furnish the vigorous exercise necessary for fitness. Participating in golf, tennis, or some other sport only once or twice a week cannot develop and maintain fitness.

Rest and sleep help overcome fatigue and restore energy to the body. Everyone needs rest and sleep, but the amount required differs for each individual. Most adults sleep from 7 to 81/2 hours a night, though some need less sleep and others need more. Young children may need more sleep at night plus a daytime nap.

Nearly everyone has trouble falling asleep occasionally. However, frequent insomnia (inability to sleep naturally) can indicate various physical or emotional disorders. Therefore, it is best to consult a doctor about any persistent sleep problem. Some people take sleeping pills to counteract insomnia, but such drugs should not be used without a doctor's prescription.

Rest and relaxation are as important as sleep. After strenuous work or exercise, a person may need a period of total rest. At other times, only relaxation or a change of pace is necessary. Any activity that differs from the normal routine of work or study can be relaxing. Pleasurable and relaxing activities help the body shed tension and remain robust. If rest and relaxation do not relieve fatigue and tension, the individual may have a physical or emotional problem.

Cleanliness controls the growth of bacteria and other germs that can cause disease. A daily bath or shower keeps the body free from dirt and odour. In addition, it helps prevent skin infections that may develop if bacteria grow and multiply on the skin. The hair should also be washed regularly.

Daily dental care is another important part of personal cleanliness. Brushing the teeth properly and using dental floss keep the teeth clean and help prevent decay and gum disease.

Medical and dental care. Regular checkups by a doctor and dentist play an important role in safeguarding health. Doctors recommend that people have medical care at the first sign of any illness. Early care can result in quicker cure. Treating oneself for more than a day or two is unwise unless the condition improves steadily.

Prevention of disease is an important part of medical care. Parents should make sure that their children receive immunization against diphtheria, German measles, measles, mumps, polio, tetanus, and whooping cough. See IMMUNIZATION.

Elements of mental health

Physical health and mental health are closely connected. Mental health plays an important role in both the way people behave and the way they feel. Emotionally healthy individuals accept themselves as they are--with all their weaknesses as well as their strengths. They remain in contact with reality, and they are able to deal with stress and frustration. They also act independently of outside influences and show genuine concern for other people.

Emotional development. Experiences during childhood strongly influence a person's mental health throughout life. An infant is completely helpless at birth and must depend on its parents for all its needs. Children remain dependent for many years, but they slowly mature and learn to do things for themselves. They make many mistakes during this long period of growth and maturation. Children thus develop the knowledge necessary to deal with difficult situations in life. This knowledge helps them maintain good mental health.

Emotional development does not end when a person reaches adulthood. Similarly, an individual's mental health continues to change from time to time. These changes result from daily circumstances that cause either pleasure or pain for the person.

Handling stress is essential for avoiding both mental and physical illness. Feelings of stress are the body's response to any threatening or unfamiliar situation. Most severe stress results from such serious events as bereavement, a divorce, or loss of a job. However, stress can occur even in pleasant situations, such as watching a football game. If not handled properly, stress can lead to physical or emotional illness. It may produce only mild symptoms, such as a cough, a headache, or a rash, but severe and prolonged stress can contribute to serious health problems, including high blood pressure and stomach ulcers.

No one can avoid stress, but a person can lessen the danger of becoming ill from it. Regular exercise and sufficient sleep strengthen the body's resistance to stress. Everyone should learn to relax by resting, taking a walk, meditating, pursuing a hobby, or by any other method that he or she finds successful.

Social relationships have an important influence on mental health. Close personal relationships with friends and relatives provide opportunities for communication, sharing, and emotional growth. Such relationships can also provide strength and support for dealing with challenging situations or personal problems.

An individual's entire social environment also affects his or her mental health. Such social problems as poverty, racism, and overcrowding contribute to situations that influence emotional health. As a result, social and economic changes are needed to help reduce the rate of some types of mental illness.

Health hazards

The nature of health problems in the industrialized nations has changed dramatically during the 1900's. Until then, most people died from infectious diseases, such as diphtheria or pneumonia. Today, however, infectious diseases are no longer the main killers. Improved sanitation, immunization programmes, and the development of antibiotic drugs have brought these diseases under control. Today, health specialists are concerned chiefly with diseases related to the aging process, unhealthy lifestyles, and environmental hazards.

Tobacco, alcohol, and drug abuse. Cigarette smoking is a principal cause of unnecessary and preventable illness and early death. Heart disease and lung cancer and other lung diseases occur at a much higher rate among smokers than among non-smokers.

Many individuals use various drugs in an effort to solve their problems or to improve their alertness, mood, or self-confidence. However, the regular use of alcohol, narcotics, or sedatives can lead to addiction and also serious damage to the body. People may become psychologically dependent on a wide variety of other drugs, including amphetamines, cocaine, LSD, marijuana, and tranquillizers. These individuals may harm themselves further by neglecting their health and nutrition. In addition, drugs can distort a person's judgment and so increase the risk of accidents.

Alcohol is the most widely abused drug in the western world. About a tenth of all drinkers become alcoholics. There is no cure for alcoholism, but the condition can be treated. An alcoholic who gives up drinking can return to a healthy, productive life.

Environmental health hazards caused by modern technology can produce serious problems. Air pollution can worsen the condition of people who suffer such respiratory diseases as asthma and bronchitis. It may even help cause some diseases, including cancer and emphysema. In some areas, insecticides and industrial wastes contaminate food and water supplies. Excessive noise can also threaten people's health. Noise coming from aeroplanes, construction projects, and industrial plants can cause hearing loss as well as emotional damage.

Occupational health hazards threaten the health of many workers. In some cases, substances involved in a person's job may cause long-term damage that appears only after many years. For example, many coal miners develop a lung disease called pneumoconiosis from inhaling coal dust. Dust also causes lung diseases among workers in the asbestos and cotton industries. Some industrial chemicals, including arsenic and vinyl chloride, cause cancer. People who work with X rays and other forms of radiation also face a health hazard unless proper precautions are taken.

Public health

Public health includes all actions taken to maintain and improve the general health of a community. Government health programmes provide most public health services. In addition, many voluntary health agencies receive contributions to combat specific diseases, such as cancer and lung disease. These agencies provide medical services, campaign for health legislation, and make important contributions to health education.

In many countries, health departments provide a wide range of services in most communities. For example, they work to prevent and control disease by providing proper sanitation, conducting immunization programmes, and enforcing quarantine regulations. Another important function of public health agencies is to provide health education for individuals, groups, and organizations.

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