Chapter 1 Foods, Nutrition and Health PDF

Chapter 1 Foods, Nutrition and Health Dr Linda Ibrahim Abuhwaileh  Food is that which nourishes the body. Food may also be defined as anything eaten or drunk, which meets the needs for energy, building, regulation and protection of the body.  Intake of the right kinds and amounts of...

Chapter 1 Foods, Nutrition and Health Dr Linda Ibrahim Abuhwaileh  Food is that which nourishes the body. Food may also be defined as anything eaten or drunk, which meets the needs for energy, building, regulation and protection of the body.  Intake of the right kinds and amounts of food can ensure good nutrition and health, which may be evident in our appearance, efficiency and emotional well-being.  Nutrition has been defined as food at work in the body. Nutrition includes everything that happens to food from the time it is eaten until it is used for various functions in the body. Nutrients are components of food that are needed by the body in adequate amounts in order to grow, reproduce and lead a normal, healthy life.  Nutrients include water, proteins, fats, carbohydrates, minerals and vitamins. There are several nutrients in each of the groups: proteins, fats, carbohydrates, minerals and vitamins; hence the plural form of these words has been used. Thus there are over 40 essential nutrients supplied by food, which are used to produce literally thousands of substances necessary for life and physical fitness.  The study of the science of nutrition deals with what nutrients we need, how much we need, why we need these and where we can get them. Nutrition is the result of the kinds of foods supplied to the body and how the body uses the food supplied.  Adequate, optimum and good nutrition are expressions used to indicate that the supply of the essential nutrients is correct in amount and proportion.  It also implies that the utilisation of such nutrients in the body is such that the highest level of physical and mental health is maintained throughout the life-cycle.  Nutritional status is the state of our body as a result of the foods consumed and their use by the body. Nutritional status can be good, fair or poor. The characteristics of good nutritional status are: an alert, good natured personality, a well developed body, with normal weight for height, well developed and firm muscles, healthy skin, reddish pink colour of eyelids and membranes of mouth, good layer of subcutaneous fat, clear eyes, smooth and glossy hair, good appetite and excellent general health.  General good health is evident by : Stamina for work, Regular meal times, Regular sleep, Normal elimination and resistance to disease.  Poor nutritional status is evidenced by apathetic or irritable personality, undersized poorly developed body, abnormal body weight (too thin or fat and flabby body), muscles small and flabby, pale or sallow skin, too little or too much subcutaneous fat,  Reddened eyes, lustreless and rough hair, poor appetite, lack of vigour and endurance for work and susceptibility to infections. Poor nutritional status may be the result of poor food selection, irregularity in schedule of meals, work, sleep and elimination.  The WHO (World Health Organization) has defined health as the ‘state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’. Malnutrition means an undesirable kind of nutrition leading to ill- health. It results from a lack, excess or imbalance of nutrients in the diet. It includes undernutrition and overnutrition. Undernutrition is a state of an insufficient supply of essential nutrients.  Malnutrition can be primarily be due to insufficient supply of one or more essential nutrients; or it can be secondary, which means it results from an error in metabolism, interaction between nutrients or nutrients and drugs used in treatment. Overnutrition refers to an excessive intake of one or more nutrients, which creates a stress in the bodily function.  Diet refers to whatever you eat and drink each day. Thus it includes the normal diet you consume and the diet people consume in groups. Diet may also be modified and used for ill persons as part of their therapy (therapeutic diets).  Nutritional care is the use of nutritional knowledge in planning meals and the preparation of these meals in an acceptable and attractive manner to feed people. It involves assessment of the exiting meal patterns and improving these in an acceptable manner. While the nutritional plan may be general for a group of people, the actual execution is individualized to suit the person’s needs and background.  Thus one has to use a lot of ingenuity to succeed in making nutritional care effective in practical terms. Health the word health refers to the condition of the body, good health not only implies freedom from disease, but physical, mental and emotional fitness as well. Functions of Food Physiological functions of food. The first function of the body is to provide energy. The body needs energy to sustain the involuntary processes essential for continuance of life, to convert food ingested into usable nutrients in the body, to grow and to keep warm. The energy needed is supplied by the oxidation of the foods consumed.  The foods we eat become a part of us. Thus one of the most important functions of food is building the body. A newborn baby weighing 2.7-3.2 kg can grow to its potential adult size of 50–60 kg if the right kinds and amounts of food are eaten from birth to adulthood. The food eaten each day helps to maintain the structure of the adult body, and to replace worn out cells of the body.  The third function of food is to regulate activities of the body. It includes regulation of such varied activities as Beating of the heart Maintenance of the body temperature Muscle contraction Control of water balance Clotting of blood Removal of waste products from the body The fourth function of food is to improve our body’s resistance to disease.  The Psychological Functions of Food. In addition to satisfying physical and social needs, food must satisfy certain emotional needs. These includes a sense of security, love and attention. Energy Growth and Renewal Functions of Nutrients The foods which we use daily include rice, wheat, dal, vegetables, fruits, milk, eggs, fish, meat, sugar, butter, oils, etc. These different foods are made up of a number of chemical components called nutrients. These are classified according to their chemical composition. Each nutrient class has its own function, but the various nutrients must act in unison for effective action. The nutrients found in foods are — carbohydrates, proteins, fats, minerals, vitamins and water. Fibre is also an essential component of our diet. The functions of nutrients are given below. Carbohydrates: Starch found in cereals and sugar in sugarcane and fruits are examples of carbohydrates in foods. The chief function of carbohydrates is to provide energy needed by our body. Those not used immediately for this purpose are stored as glycogen or converted to fat and stored, to be mobilised for energy supply when needed.  Fats: Oils found in seeds, butter from milk, and lard from meat, are examples of fats found in foods. Fats are concentrated sources of energy, carriers of fat soluble vitamins and a source of essential fatty acids. If excess fats are taken in the diet, these are stored as fat reserves in the body. Energy taken in excess of body needs, is stored as fat in the body.  Proteins: Casein from milk, albumin in egg, globulins in legumes and gluten in wheat, are examples of proteins occurring in foods. The main function of protein is the building of new tissues and maintaining and repair of those already built. Synthesis of regulatory and protective substances such as enzymes, hormones and antibodies is also a function of food proteins. About 10 per cent of the total energy is supplied by proteins in the diet. Protein, when taken in excess of the body’s need, is converted to carbohydrates and fats and is stored in the body.  Minerals: The minerals calcium, phosphorus, iron, iodine, sodium, potassium and others are found in various foods in combination with organic and inorganic compounds. Minerals are necessary for body- building, for building of bones, teeth and structural parts of soft tissues. They also play a role in regulation of processes in the body, e.g., muscle contraction, clotting of blood, nerve stimuli, etc.  Vitamins: Fat-soluble vitamins A, D, E and K and also water-soluble vitamins C and B group are found in foods. These are needed for growth, normal function of the body and normal body processes.  Water: We get water in foods we eat and a major part from the water we drink as such and as beverages. Water is an essential part of our body structure and it accounts for about 60 per cent of our body weight. Water is essential for the utilisation of food material in the body and also for elimination of food waste. It is a regulator of body processes such as maintenance of body temperature. All individuals need the same nutrients for the same body function. The only variation is in the amounts of each nutrient required according to age, size, activity, etc. For example, all persons need energy for work, but a man, who carries loads may need more energy than a man, who works in an office at a desk job.  Food Composition Most food contain more than one nutrient. The nutrient contents of foods have been determined by analysing these in the laboratory. The composition of over 650 Indian foods has been determined. Of these, the nutritive value of about 160 foods is presented in the  Appendix F. The food composition tables give the concentration of nutrients in 100 g of the edible portion (E.P.) of the food. Therefore it is important to know how much of the food purchased is edible. In some foods, such as milk, butter, sugar, the edible portion is 100 per cent. In fruits and vegetables, it varies from 65 per cent in bananas to 98 per cent in tomatoes.  Vit. A Vit. C Minerals Foods Moisture Calories Protein (g) (mcg.) (mg) & Vit. B-Comp Cereals-rice, 10 340 7 to 12 — — Some Wheat, bajra, Jowar Dals, legumes 10 340 17 to 25 — — Some2 Milk 85 70 3 48 — Some3 Eggs 75 170 13 960 — Some Meat, fish, poultry 75 100–190 18 Some — Some Leafy & 90 20 2 1,800 30 Some Orange-yellow Vegetables & Fruits Fruits-Vit. C-rich 85 50 1 Some 50 Some Other vegetables 90 30 2 Some Some Some Other Fruits 85 50 1 Some Some Some Roots & tubers 60–85 50–100 1 Some Some Some Oils & Fats 0 900 — — — 7504 Sugar, jaggery 0 400 — — — —  Food Exchange Lists In 1950, the American Diabetes Association and the American Dietetic Association collaboratively developed a system of food lists to help diabetic patients to select foods in their diets. Similar food lists were prepared in other countries to help diabetics to choose their foods. In India also food lists were prepared based on the foods available and our meal pattern.  Since India is a large country there are three major agencies that have evolved their food exchange lists. These agencies are dietetic departments of major regional hospitals, the Home Science colleges, which train dietetic students, and the dietetics department of the National Institute of Nutrition. These are presented in Appendix B.  Each of the list includes a group of foods, which supply about the same calories in the portion indicated. Each food choice within a list is called an exchange. It represents an amount of food that has about the same macronutrient value as other foods in the same group. The exchange lists are very useful tools in diet planning in hospitals and in personal diet management in the home.  Nutrient Density It refers to the quantity of one or more nutrients supplied by a food in reference to its calorie content. For example, if one compares the protein content of isocaloric portions of dal, bread and milk, one can see that dal has the highest nutrient density for protein, milk next and bread the least. Calories Protein Dal 85 5.5 Milk 85 4.0 Bread 85 2.4  Thus nutrient density is an important aspect to be considered in selection of foods, especially in diets of children, pregnant women, nursing mothers and in therapeutic diets for patients. Study Questions Explain the terms nutrition, nutrients, nutritional care, optimum nutrition and undernutrition. How is food related to health? Discuss the physiological functions of food. “Food is also used to satisfy social and psychological needs”. Explain this statement by giving examples. What do you understand by adequate nutrition? Explain the concept of exchange lists. What is nutrient density?