Introduction to Nursing Nutrition Fundamental: A Review Guide For Beginner

Introduction

Nutrition is the process and science of consumption, absorption and using nutrients needed by the body for growth, development, and maintenance of life. It is a multidisciplinary subject with the community as its, practice area. Nutrition the body needs with the role of food (dietary input) in the maintenance of health. The essential requisites are:

• Achievement of optimal growth and development, reflecting the full expression of one’s genetic potential.
• Maintenance of structural integrity and functional efficacy of the body tissue necessary for an active and productive life.
• Sound mental health.
• Ability to withstand the imminent process of ageing with minimal disability and functional impairment.
• Ability to resist the adverse effects of environmental toxins and pollutants and combat digging.

Foods are required in the body to provide energy, promote growth, repair worn-down body tissues and sustain the regulatory processes. As such all foods consumed by man may be grouped into three main categories based on the function they perform, as listed in Table 1.1

Nutrients, their function and sources

  Nutrients

Generally, nutrients are divided into the following two main classes:

Macronutrients: Requires in larger quantities, are water, carbohydrates, fats and proteins. These constitute the bulk of the diet and supply energy for body activity and building blocks needed for growth and maintenance. They also provide compounds that regulate body process.

Micronutrients: Requires in smaller quantities, milligrams (gm) to micrograms ( g). These are vitamins and mineral elements that catalyze the utilization of macronutrients.

Balanced Diet: Balanced diet is one that consumes all nutrients in the correct proportion required by an individual to promote and preserve good health. It should help to achieve and maintain desirable body composition and large capacity for physical and mental work. Developing good eating habits. Good meal planning is both an art and a science.

In meal planning, it is suggested that the 20% of the allocated budget is to spend on cereals and their products, 20% on fruits and vegetables, 25% on meat, fish, eggs, poultry, legumes and pulses, 20% on milk and their products, and 15% n fats and sweets.

Water

Water is essential for life. Without food, one can survive for about a month, but in the absence of water for a few days only. The significance of water is evident from the fact that it is the largest constituent of the human body. More than 60% weight of an adult man is water. Women contain about 45 to 55% since they have more fat, which drier (20% water) than muscle (75% water). Babies contain more water than an adult does and the elderly slightly less. Most of it (about 55%) is held inside the cell as intracellular fluid. While the rest (about 45%) is contained in the extracellular fluid. Relatively little, about 7.5% of total water, is in the bloodstream that forms part of the extracellular fluid. These fluids are in a dynamic state since they constantly undergo changes in composition. Nutrients and oxygen are taken up by the cells that in turn excrete carbon dioxide and other waste materials. In spite of this, the composition of various body fluids remains almost constant.

 Functions

Water is required in the body primarily the following important functions:

• It is used as a building material in every cell – fatty tissues contain 20%, bone 26% and striated muscles 75% water.
• It acts as a lubricant in joints and between the internal organs.
• It helps to regulate body temperature.
• It serves as a medium in which nutrients, enzymes and other chemical substances are dispersed or dissolved.
• It is a medium in which intercellular chemical reactions take place.
• It takes participation in chemical reactions, especially the hydrolytic ones.
• It acts as a transport medium for carrying nutrients to cells and removing wastes from the body.

Sources of water in the body     

There are three considerable sources of water supply in the body:

• Daily diet supplies from 750 mL to 1000 mL water (about 25 to 35% of the intake)
• Water produced in the body as a result of metabolic activity (utilisation of nutrients) supplies from 10 to 15%of the daily intake.
• Water is taken to drinking water, beverages etc account for 50% or more of the daily intake.

 Dietary Requirements of Water

The intake of water is governed by several factors including diet, age, climate, activity, etc. More water is needed if food intake is more. Water is required in amounts of 1 mL for each kilocalorie of energy expended or about 2,500 mL a day for a person consuming 2,500 kcal. More water is needed when the diet is rich in protein and salt. The water demand of an individual increase with age. The need for water during hot weather is much higher than the cold weather. Much more water is needed in tropical climate depending upon the temperature, relative humidity and activity.

Carbohydrates

Carbohydrates contain carbon, hydrogen and oxygen. They are widely distributed in plants in which they are formed from carbon dioxide of the atmosphere and water from the soil through photosynthesis. The nutritionally important major groups of carbohydrates are sugar (monosaccharides and disaccharides), oligosaccharides and polysaccharides (starch, cellulose, pectic substance and related compounds). Carbohydrates constitute by far the greatest portion of diet in developing countries, as much as 80% in some cases. In industrialized countries, 45 to 50% carbohydrates are included in the diet of a person.

Carbohydrates are classified into two broad groups, simple and compound carbohydrates. Simple carbohydrates include monosaccharide and disaccharide. Compound carbohydrates include Polysaccharide and Oligosaccharide.

Table 3.1: Recommended daily dietary allowances for energy

Dietary Requirements

In an optimum diet, the energy-yielding carbohydrates (sugars and starches) should provide at least 55% of the total energy for all ages except children less than 55% of the total energy for all ages except children less than two years. This should be derived from a variety of carbohydrates sources to meet the requirements of essential nutrients. When consuming carbohydrate levels above the optimum, including carbohydrate-containing beverages, engaging in regular physical activity is essential. Excess Intake of sugars should be avoided since these are energy dense.

Lipids

Lipids are a group of naturally occurring substance that, in general, are soluble in organic solvents (such as chloroform, diethyl either, carbon tetrachloride, petroleum ether, etc.) but are insoluble or sparingly soluble in water.

Included in this group are fats, oils, waxes (simple lipids), phospholipids, glycolipids, lipoproteins (compound lipids), fatty acids, alcohols, hydrocarbons (derived lipids) and tocopherols, vitamin K and steroids (substances associated with lipids in nature). Chemically, lipids consist of oxygen, carbon and hydrogen. Some lipids also contain phosphorus and nitrogen. Some lipids also contain phosphorus and nitrogen. Some nutritionally important lipids are fats, oils, phospholipids, glycolipids, sterols and steroids.

Further, they are classified as fats and oils, phospholipids, glycolipids, sterols and steroids. Fats and oils, the common constitute of foods, make up a sizeable percentage of food lipids. Fats are esters of saturated and unsaturated fatty acids with glycerol. In developing countries, 8 to 10% of total energy is derived from fats, while in industrialized countries up to 45% energy is obtained from this source.

Fats are a target for replacement owing to release of over twice the amount of energy than carbohydrates and potential risk of several diseases. Epidemiological studies indicate an association between high intake of fat, saturated fat, and cholesterol with disorders such as obesity, cardiovascular diseases, and cancer of colon, rectum, breast and prostate. In the search to offer consumers food low in fat content, nutritionists have developed several low-calorie-free fat substitutes.

Proteins

Proteins are complex nitrogenous compounds of very high molecular weight, which, besides nitrogen contain carbon, hydrogen and oxygen. There are more than 20 naturally occurring amino acids that give rise to about 2000 particular proteins existing in nature. These are more complex than either carbohydrates or lipids in terms of both size (molecular weight) and verity of the constituent unit. Proteins vary from tissue to tissue within a living organism and corresponding tissue of various species. Most proteins also have Sulphur, and some contain phosphorus. These elements form amino acids that are linked together chemically to give the specific structure and characteristics properties to the individual proteins.

Amino acids are the building blocks of proteins. The type of protein is determined by the sequence of amino acids. For example, the protein in hair, keratin, is dissimilar from casein, a milk protein.

Protein is an abundant component of the human body. It is exceeded only by water. On half of the dry weight of the body is protein. In the human body, it is distributed in the following manner.

Table 5.1: Proteins Content in human body

Table 5.1: Recommended protein intake for various age groups.

Animal proteins are of high quality, Grain products are in low proteins, fruit and vegetable provide little protein.

 Functions of Proteins

Dietary proteins provide amino acids that are required to build and maintain tissues. They are also involved in the production of enzymes, some hormones and antibodies. Some proteins help to regulate body processes. In the absence of energy-giving nutrients, proteins also provide energy. Specifically, proteins provide the following functions to the body.

• Body Building
• Building substances for enzymes, hormones and antibodies
• Regulation of body processes
• Control of acid-base balance in the tissues
• Energy provider

 Proteins Requirements

The minimum protein requirement for adults depends upon the number of active cells in the body. Men have more muscle cells and, therefore, requires slightly more than women and the elderly.

Occasional consumption of a high protein diet is not detrimental for adults. Consumption of excess proteins over long periods increases the tendency of development of kidney stones due to excessive urea formation. Too much protein is injurious for babies.

The body can become depleted of protein by a diet low in protein. Children are more affected and suffer from Kwashiorkor and Marasmus.

Animal proteins are of high quality. Grain products are low in proteins. Fruits and vegetables provide low protein.

Table 5.2: Nutritional content of some selected foods.

Source: Hussain 2001

Vitamin and Inorganic Materials

 Vitamins

Vitamins are a group of organic substances, chemically highly diversified, that exists in foods. These functions in a wide variety of capacities within the body. These function in a wide variety of capacities within the body. These are essential in minute quantities for normal growth and maintenance of life. Vitamins are required for the metabolic processes and participate in several chemical and biochemical reactions. The distinguishing feature of the vitamins is that they generally cannot be synthesized by mammalian cells and, therefore, must be supplied in the diet. These are classified into the following two groups based on their solubility in water or fat.

Fat-Soluble Vitamins: The fat-soluble vitamins are soluble in fats and are supplied to the body through fat-containing foods. In the body, these are stored wherever fat is deposited and are excreted exclusively in the faeces. Vitamin included in this group are A, D, E and K.

Water-Soluble Vitamin: These are almost collectively concerned with the transfer of energy and protein metabolism. Some are involved in the formation of red blood cells. Vitamin B and C are water-soluble vitamins.

 Inorganic Materials

Substances regarded as inorganic materials are those preset in ash when food or any living organism is cremated.  So, other than oxygen, hydrogen, carbon and nitrogen are excluded, since these form organic compounds and are not found in ash.

The inorganic materials have two general body functions-building and regulating. In their building capacity, these substances for part of the skeleton and all soft tissues. Hence, these are found in the rigid body structures (bones) and soft body tissue (muscles). In their regulatory function, inorganic materials are associated with a variety of systems. These include heartbeat, clotting of blood, maintenance of internal pressure of body fluid, nerve responses and transport of oxygen from lungs to the tissue.

Inorganic materials are required in the human body in relatively minute quantities. Calcium, chlorine, iron, magnesium, phosphorous, potassium, sodium and Sulphur are needed in slightly larger amounts than chromium, cobalt, copper, fluorine, iodine, manganese, molybdenum, selenium and zinc that are required in trace amounts. In addition, some of these elements like aluminum, arsenic, boron, nickel and silicon are found in traces in the body ash. Most mineral elements are essential in the diet and their deficiency results in some type of nutritional disorder.

Digestion

Digestion is the physiological process of dismantling complex food nutrients (carbohydrates, fats and proteins) into particles small enough to be transferred into the bloodstream. In this process, insoluble food is changed into soluble forms through mechanical and chemical processes. This process occurs in the gastrointestinal or digestive tract.

The digestive system consists of two parts, the alimentary canal and the digestive tract. Digestive organs are mouth, oesophagus, stomach, small intestine and large intestine. Several glands (salivary glands, gastric glands, intestinal glands, liver and pancreas) pour secretions onto the food as it passes through parts of the digestive tract.

Absorption and Metabolism

Complex food nutrients entering the mouth undergo a process of disintegration in the gastrointestinal tract. As a result, carbohydrates, lipids and proteins are split into their basic units by various enzymes in the gastrointestinal tract.

 Absorption

In the mouth: No significant absorption occurs through the lining of the mouth

In the stomach: Simple substances like water, ethyl alcohol and sugar can pass through the lining of the stomach into the bloodstream in small quantities.

In the small intestine: By the time food reaches the small intestine, it is changed into soluble components, this enables it to pass into the blood and lymph stream. For this purpose, there is a 7m long intestine and many thousands of villi.

In the large intestine: The large intestine has two main functions. Firstly, it absorbs water from the residue moving through it. Secondly, it stores resultant faces until expelled through the anus.

Metabolism

The utilization of food in the body is termed as metabolism, i.e., it includes all chemical and biochemical changes that food components undergo in the body. There are two phases of metabolism, namely:

Anabolism: The processes by which absorbed products of digestion are made part of the body – used to replace body constituents and to form new cellular materials growth.

Catabolism: These are the processes that occur largely by an oxidation reaction, whereby a cellular substance is broken down to smaller molecules.

In the body cell, anabolism and catabolism occur simultaneously.

Nutrition Throughout the Lifecycle

The nutritional requirements of individuals vary depending upon several factors including age, sex, activity, income, climate, environment, habits and other factors.

 Infant Nutrition

Nutrition during the first year of life is critical because it is a period of rapid growth and development. Therefore, a healthy, balanced and adequate diet is required to fulfil all the requirements of a baby, i.e:

• To provide energy to creep, crawl, play, learn, gurgle and smile.
• For strength to fight infection and diseases
• For good health, a key for happiness all through life right at the start

Mothers milk is considered primary food for infants. it is not only the best but is a must for the infant. It contains all essential nutrients required for the infant in the proportion necessary for the growth. It is a good source of carbohydrates, proteins, vitamins and mineral elements.

Table 9.1: Recommended dietary allowances of infants (0-6 months) and average composition of human, cow and buffalos’ milk (values per 100 mL)

Source: Srilakshami 1993

9.2 Children Nutrition

The children are in a rapidly growing state; hence their nutritional requirements increase with age. Their physical activity is high, as they tend to play more.

Table 9.2: Daily dietary recommendation for children

Source: Srilakshmi 1993

Adult Nutrition

Adulthood is a stage where one has attained maximum growth. No new body structure and formed. Adults only need maintenance ration. They require energy for various purposes. the average calories requirements for a sedentary adult man are 2400 kcal, while a physical laborer needs 3800 kcal or even more. Proteins are needed to replace worn-out tissues and build enzymes and hormones. About one-gram protein per body weight is needed for both men and women. It is suggested that fats and oils should provide not more than 30 – 40 % total energy. Among the mineral’s elements, women need more iron (2 mg per day) than men. The requirements of vitamins are slightly different for men and women.

 Nutrition of Pregnant and Lactating Mothers

The nutritional requirements of pregnant and lactating women are higher than others. In addition to their own needs, they have to cater to the requirements of the fetus or the infant.

Daily consumption of meat, fish or pulses is essential. One egg a day is sufficient. Fresh fruits and vegetables should be consumed at least twice a day. Iron must be supplemented. The requirements can be met if food is occasionally cooked in iron utensils. At least half liter milk must be consumed to provide, among other nutrients, calcium.

Lactating mothers’ dietary intake should be high enough to meet the requirements of both mother and child. It should consist of all five-food groups.

Table 9.3: Recommended dietary allowances of moderately active normal adult and pregnant women, and lactating mothers

Source: Srilakshami 1993

Diet Related Disease

Diet is one of the major environmental influences that affect human health. The natural foods are rich in substances the beneficially affect the health. At the same time, there are components that may be harmful. While food is consumed for healthy living, it is known to cause numerous diseases. The affluent societies have more to eat (over- nourishment), while the poorer people do not have even adequate supply of calories and proteins (under-nourishment). Consumption of food is non-optimal quantities has been implicated in a number of diseases. Some knowledge about such disorders that plague the society is essential.

 Malnutrition

Consumption of non-optimal quantities of food, either in excess or below the b0dy requirements over a prolonged period. May lead to specific health disorders. Malnutrition is the name given to such a situation that describes over- or under- consumption of food.

Over-Nutrition: Usually common in well-to-do families in developing countries who eat in excess and do very little physical work. It is also a feature in the individual usually less knowledgeable about nutrition in the developed world. Eating excessive quantities of minerals elements and some vitamins have adverse effects the health.

Under-Nutrition: The more serious form of malnutrition, universal among poorer families and nations. The result from the consumption of poor diet over prolonged periods.

 Some other Common Diseases

• Deficiency of carbohydrates and proteins in the human diet is a prevalent form of undernourishment.
• Protein deficiency occurs in poor families and is responsible for the disease called kwashiorkor in children.

References

Beauman, C., et al. (2005). “The principles, definition and dimensions of the new nutrition science.” Public health nutrition 8(6a): 695-698.

Carr, T. and K. Descheemaeker (2008). Nutrition and health, John Wiley & Sons.

Currie, J. (2003). US food and nutrition programs. Means-tested transfer programs in the United States, University of Chicago Press: 199-290.

Dijkstra, J., et al. (2005). Quantitative aspects of ruminant digestion and metabolism, Cabi.

Hamilton, E. M. N., et al. (1991). “Nutrition: Concepts and controversies.”

Khan, M., et al. (2001). “Food composition table for Pakistan.” Peshawar: University of Agriculture.

Lanham-New, S. A., et al. (2019). Introduction to human nutrition, John Wiley & Sons.

Lawrence, J., et al. (2016). Dietetic and Nutrition Case Studies, Wiley Online Library.

Leaf, A. and P. C. Weber (1987). “A new era for science in nutrition.” The American journal of clinical nutrition 45(5): 1048-1053.

Mann, J. and A. S. Truswell (2017). Essentials of human nutrition, Oxford University Press.

Müller, O. and M. Krawinkel (2005). “Malnutrition and health in developing countries.” Cmaj 173(3): 279-286.

Preedy, V. R., et al. (2011). Handbook of behavior, food and nutrition, Springer Science & Business Media.

Schnecman, B. (1989). “Dietary fibre: scientific status summary.” Food Technology 43: 133-139.

Shils, M. E. and M. Shike (2006). Modern nutrition in health and disease, Lippincott Williams & Wilkins.

Smolin, L. A. and M. B. Grosvenor (2019). Nutrition: Science and applications, John Wiley & Sons.

Sobal, J., et al. (1998). “A conceptual model of the food and nutrition system.” Social Science & Medicine 47(7): 853-863.

Srilakshmi, B. (2006). Nutrition Science, New Age International.

Copyright material no part of this should be copy or photograph without written permission of the Author.