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Tuesday, 29 January 2013

NUTRITION

TOPIC :: HEALTH :: NUTRITION

Nutrition begins with foods. The study of nutrition involves everything that, the body does with food in order to live, like function and grow. Foods that are eaten regularly make a diet. Although were you live and how you eat play a major part in your dietary habits, food choices vary from person to person. What people eat affects their health and how they live. Plants make their own food from, water and air. People cannot make their own food but eat plants and meats to survive. The body's most important need is for energy. To get energy, it needs food as a fuel and oxygen to burn it. The amount of energy food  produces is  called calories. A food calorie,  is the amount of heat required to raise the temperature of (i.e.,2.2 pounds) of water 1 degree Celsius (i.e., 1.8 degrees Fahrenheit).

The body changes the calories in food into energy, which is very necessary for the little things like blinking an eye to running a race. Energy is also used for the growing process, for rebuilding damaged cells and for regulating the body. The number of calories needed each day depends on  how much energy your body uses. An active kid can need more calories than an adult who works at a desk. The body needs more calories in cold weather to stay at an even temperature.

If  a person consumes more food than required to meet the body's needs, the extra calories  become fat . That causes weight gain. Eating too little causes weight loss because the fat is used for energy. One pound of stored fat has almost 3,500 calories.

If weight loss is desirable, the best way to lose weight is by eating less of high calorie foods and getting more exercise. Usually for most people a safe limit for losing weight is 2 pounds a week.  Quick and easy weight-loss diets are fads; because most are unbalanced, puting emphasise on one kind of food and excluding others. To function, humans must have nutrients. The most important nutrients for people are proteins, carbohydrates, fats and oils, minerals, vitamins and water.                                                                                                                                Proteins are made up of amino acids, small units necessary for growth and tissue repair. Protein is the body's most abundant substance except for water and, maybe, fat. Animal foods such as meat, fish, poultry, milk and eggs are rich in protein. Good plant sources of protein are beans, peas, nuts, bread, and cereals.

Combining plant sources, such as peanut butter with whole grain bread or rice with beans; which provides excellent protein. So does combining plant and animal sources such as cereal and milk or macaroni and cheese.

Starches and sugars are carbohydrates, the main source of the body's energy. Carbohydrates account for about half of the calorie intake for most americans and  four fifths of the calories in diets of african and asian people. Foods rich in carbohydrate are also the main source of protein for most of the world. Rice, wheat, corn and potatoes are common rich sources of carbohydrates.

Sugars aren't essential foods. They provide energy but no nutrients. Because of that sugar is called an "Empty Calorie" food. Occasional, sugars are not harmful to a healthy, but to much sugar can cause  tooth decay  when eaten between meals, especially sticky snacks  that stick to the teeth.

Fats and oils are a concentrated source of energy. Fats in the diet are a must for good health. They make certain types of vitamins available for use in the body. They provide a cushion for vital organs. They make up part of all body cells and they help to maintain body temperature. Fats also slow aches of hunger because a food mixture containing fat remains longer in the stomach.
 
Nutritionists classify  different types of dietary fats or fats in food. Saturated fats usually are solid  and come from animals. In many standard diets, fat from meat is the main source. It is  a fact that saturated fats can raise the level of cholesterol in the blood. Cholesterol is a waxy substance made by the body. It helps to form digestive juices and does other important work. It is always in the body no matter what is eaten. When the body cells can not absorb any more cholesterol any excess begins to collect in the walls of the blood vessels and gradually narrows them. This  may lead to a heart attack or stroke.                                                          

Minerals are neither animal or vegetable; they are in-organic. Almost all foods contribute to a varied intake of essential minerals. Most minerals are easy to gain in quantities required by the body. A major exception is iron for children under age 4 and teen girls and women in the childbearing (Pregnant) years. These people need more iron than a normal diet may give. Iron helps to build red blood cells. It also helps the blood carry oxygen from the lungs to each body cell. Rich sources of iron are meat, especially liver; egg yolks; and dark green vegetables.

Everyone at every age needs calcium. This mineral builds bones and teeth, and it is essential for blood clotting. The best sources are milk and hard cheese. Others are leafy greens, nuts and small fishes like sardines with bones that can be eaten.

Phosphorus works with calcium to make strong bones and teeth. A diet that provide enough protein and calcium also provides enough phosphorus. Other important minerals are sodium, potassium, iodine, magnesium, zinc and copper.               
The discovery of vitamins began early in the 20th century. It's likely that some vitamins still are undiscovered. Eating a wide variety of foods ensures getting enough vitamins. All living things need vitamins for growth and health. The body either cannot produce them at all or cannot normally produce them in needed amounts and  must absorb them from food. Each vitamin has specific roles. Many reactions in the body require several vitamins and the lack or excess of any one can interfere with the function of another.

Four vitamins A, D, E, and K are called the fat-soluble vitamins. They are digested and absorbed with the help of fats that are in the diet.

Vitamin A is needed for strong bones, good vision and healthy skin. It's found  in dark green and yellow fruits and vegetables.

Vitamin D is essential for children, because it helps calcium and phosphorus to form straight, strong bones and teeth. With sunlight on the skin, the body can produce its own vitamin D. Babies and young children often need vitamin D supplement.

Vitamin E helps to protect vitamin A and red blood cells. It's found in a wide variety of foods and almost everyone gets enough.

Vitamin K is one vitamin that is made in the human body by bacteria that live in the intestinal tract. Small amounts are found in the green leaves of spinach, kale, cabbage and cauliflower and also in pork liver.

Fat soluble vitamins can be stored in the body for long periods. They are stored mostly in the fatty tissue and in the liver.

The vitamin B group of several vitamins helps to maintain healthy skin and a nervous system. B vitamins also help to convert carbohydrates into energy. Vitamin C is needed for building the connective tissue that holds body cells together. Vitamin C is essential for healthy teeth, gums and blood vessels. It also helps the body to absorb iron. These water-soluble vitamins are not stored in the body for long. Good sources should be eaten every day.

In order to live, every cell in the body must be washed in water. Water is needed to carry other nutrients, to regulate body temperature, and to help get rid of waste wastes. Water is about 60 percent of an adult body weight. Water is found in most foods and in most fruits are more than 90 percent water. 
 
In the early 1990s' the basic four food groups, were reworked into the more balanced and healthy food guide pyramid. The  pyramid has at the bottom the grain group; on the second level are the fruit and vegetable groups; on the third level are the meat and dairy groups; and at the top is the fats, oils and sweets group.

Foods from the food guide pyramid can be part of any meal. A grilled cheese sandwich or a bowl of whole-grain cereal is just as nutritious in the morning as it is at noon. A good breakfast consists of any foods that supply about one fourth of the necessary nutrients for the day.

The United States government publishes guidelines for appropriate nutrient a person should get. These are known as the Recommended Dietary Allowances. Just the same as wise shoppers get the most for their money, so do good consumer buy foods that give the most nutrition for the lowest number of calories. For example, snacks can provide about one fourth of the calorie requirements among teenagers. Those snacks  provide that much of the day's needs for protein, minerals and vitamins. Sandwiches, fruit and milk make good snacks for  teenagers.

Special diets for people with health problems should be prescribed by  a doctor. Doctors  usually refer patients to a dietitian, who write up an private diet plan.
The typical diet American diet usually has much  more salt than the body needs. People with high blood pressure have to avoid as much salt as possible. Diabetes  is another disease that needs careful meal planning. When a person has diabetes the body doesn't  normally use of  blood sugar. If  a person  develops diabetes later in life, it usually is controlled with diet alone. Diets high in fat and cholesterol have been connected with blocking  the arteries, a common reason in heart disease and stroke. Scientist show that this condition can begin in adolescence or earlier.

Some people are vegetarians; that is, they eat no meat and sometimes no eggs, cheese, or milk. People who don't eat all animal products are called vegans. These people must plan their diets carefully to get balanced nutrition.

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