UNIT 4 Types of nutrients_082655.pdf
- 2. What are Nutrients? Are substances obtained from food and are needed by the body Nutrients are classified as essential or nonessential. Nonessential nutrients are manufactured in the body and do not need to be obtained from food Examples include cholesterol, a fatlike substance present in all animal cells.
- 3. . Conti…. Essential nutrients must be obtained from food sources, because the body either 1. does not produce them or 2. produces them in amounts too small to maintain growth and health. Essential nutrients include water, carbohydrates, proteins, fats, vitamins, and minerals.
- 4. Types of Essential Nutrients Based on size Macro-nutrients-Carbohydrates, proteins, and fats micro-nutrients -Vitamins and minerals and water (vital nutrient sustaining all life processes) Based on how they are synthesized Organic nutrients- Carbohydrates, fats, proteins and vitamins are organic nutrients/substances because plants can synthesize them by the process of photosynthesis. Inorganic Nutrients- minerals that are extracted from the soil by plants and in turn man obtain them from plants or animals that has eaten the plants
- 5. Functions of nutrients Human beings require food to 1. Grow 2. Reproduce 3. Maintain good health. Without food, our bodies could not stay warm, build or repair tissue, or maintain a heartbeat.
- 6. CARBOHYDRATES These are organic compounds of carbon, hydrogen and oxygen (CHO). They are generally starches, sugars and cellulose. SOURCES Plants are the main source of carbohydrates in the human diet Root tubers; irish potatoes, cassava, yam and carrots Fruits; banana, oranges, peaches Grains; maize, rice, wheat, groundnuts Stems; sugar cane Vegetables and milk are other sources. Starch is a type of carbohydrates found in vegetable and lactose from milk
- 7. CLASSIFICATION CHOs are classified into 3 groups Monosaccharide Disaccharide and Polysaccharides
- 8. Monosaccharide These are simplest form of carbohydrates and often called simple sugars. These are the ones which are absorbed by the body. These include glucose, fructose and galactose. Glucose; sources are grapes, sweet potatoes. It is the form in which sugar circulates in the blood and oxidized to release energy. 1 gram of carbohydrate is oxidised completely to give 4 calories. During metabolism all forms of other sugars are converted to glucose
- 9. Fructose-Is the sugar found in fruits and honey. It is the sweetest of all sugars Galactose- is produced from lactose and is converted to glucose in order to be absorbed by the body. Disaccharide These are made up of 2 monosaccharides for example; Sucrose= fructose + glucose Lactose= galactose + glucose Maltose= glucose + glucose Sources Sucrose (table sugar) found in sugar cane, sorghum cane, brown sugar, pineapple Lactose found in milk , it is formed in the body from Maltose is found in malt products and germinated cereals
- 10. Polysaccharides These are complex carbohydrates made up of many units of monosaccharide such as starches, glycogen, cellulose. Starches and glycogen are the only polysaccharides of nutritional importance because they can be ingested in the human gut. Starches These consists of two polysaccharides namely amylose and amylopectin. Starch is the carbohydrate found in plants. Amylose The amylose molecule consists of glucose units between 70- 350 joined in a straight chain.About 20% of starches is amylose Amylopectin This molecule consists of up to 100,000 units of glucose joined in a branched chain. It consists of 80% of starches. Glycogen This is a carbohydrate found only in animals. It can be thought of as a reserve in animals, just like starch is the reserve for carbohydrates in plants.
- 11. Glycogen Glycogen is composed glucose units with branched chains. It is soluble in water. Animals are capable of storing glycogen in muscles and the liver. When required the glycogen is converted into glucose and used by the body to provide energy. The enzyme which converts glycogen to glucose is called glucagon. Glucose can be formed from proteins and fats by gluconeogenesis which occurs in the liver and kidneys. Excess carbohydrates Excess intake of carbohydrates may lead to obesity. Low carbohydrates If carbohydrates are not enough or absent, fats and protein are used to provide energy needed by the body.
- 12. Functions of carbohydrates They provide energy The carbohydrate dextran is a polysaccharide used in medicine as a blood-plasma-volume expander to counteract acute shock; another carbohydrate, heparin sulfate, is a blood anticoagulant. Also used in the production of adhesive materials, sizing materials, and emulsions
- 13. Digestion of carbohydrates Digestion: This is a chemical break down of different complex compound present in the food particles which have been physically cut by the action of teeth and jaws. It is brought about by the means of chemical compound called enzymes Amylase, found in saliva and in the intestine, breaks starch, dextrin, and glycogen into maltose. Maltase breaks maltose into glucose, it breaks cane sugar into glucose and fructose; lactase breaks milk sugar into glucose and galactose.
- 14. Digestion in the mouth In the mouth, food is chewed and mixed with saliva. Saliva is composed of water, mucin (lubricates food) and amylase. chewing reduces the food to be suitable for swallowing and increased the available Digestion in the stomach From mouth the food passes through the oesophagus into stomach which acts like a reservoir because food needs to be consumed at intervals. No digestion of CHOs takes place in the stomach.
- 15. Digestion in the intestines The small intestines are composed of 3 parts; these are duodenum, jejunum and ileum. Of the 3 pancreatic enzymes, amylase is the one which act on starch and change it into maltose. This means that the starch which was not digested in the mouth can now be acted upon in the small intestines. From the duodenum, the food enters in ileum. In here it meets the intestinal juice which contains the following enzymes; enterokinase, peptidase, maltase and sucrase.
- 16. Among these enzymes, maltase and sucrase are the ones which act on CHOs: maltase, acts on maltose and changes into 2 glucose molecules, sucrase acts on sucrose as a result which yields fructose and glucose. Absorption Nearly all the digested food is absorbed in the ileum Properties of the ileum that are important to its function of absorption : It provides large surface area. Its internal surface is increased by finger like projection called villi. The lining epithelium is thin and fluids can pass fairly rapidly through it. There is a dense network of blood capillary in each villi.
- 17. Absorption of carbohydrates conti…. Glucose is absorbed into the bloodstream through the intestinal wall. Some of this glucose goes straight to work in our brain cells and red blood cells, while the rest makes its way to the liver and muscles, where it is stored as glycogen (animal starch), and to fat cells, where it is stored as fat.
- 18. Daily requirements of carbohydrates The body needs about 45 to 65 percent of your total daily calories. Effects of carbohydrates deficiency and excess Effects of carbohydrates deficiency causes marasmus while excess causes obesity, Non-insulin dependent diabetes mellitus, dental carries.
- 19. PROTEINS Proteins are made of smaller units called amino acids. Dietary proteins are powerful compounds that build and repair body tissues, from hair and fingernails to muscles. In addition to maintaining the body’s structure, proteins speed up chemical reactions (enzymes) in the body They serve as chemical messengers, fight infection (immunoglobulins) Transport oxygen from the lungs to the body’s tissues (haemoglobin).
- 20. Cont….. protein provides 4 calories of energy per gram The body uses protein for energy only if carbohydrate and fat intake is insufficient. When tapped as an energy source, protein is diverted from the many critical functions it performs for our bodies.
- 22. Based on nutritional requirements: Essential amino acids: • These cannot be made by the body. • As a result, they must come from food. • Examples: Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Non essential amino acids: • These can be synthesized/made by the body. • Examples: Alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
- 25. Classification based on composition Proteins are classified into simple, compound and derived Simple proteins These are made up of only amino acids. Examples albumin found in egg, serum in blood. Globulin found in blood. Conjugated/Compound proteins These are compounds of single and other none protein groups Examples; Glycoprotein, Mucoprotein, Phosphoprotein, Lipoprotein, Chromo-protein
- 26. CLASSIFICATION BASED ON QUALITY Complete Proteins These are amino acid which contain all the amino acids in sufficient manner e.g. animal foods Incomplete Proteins These are proteins in which one or more of the essential amino acids are not present e.g. beans, maize, groundnuts
- 27. CLASSIFICATION BASED ON FUNCTION Structural proteins- connective tissue Contractile- muscle Antibodies- gamma globulin which destroys bacteria Blood proteins- albumin, fibrinogen for clotting of blood Hormones – facilitation of body metabolic activities Enzymes- for digestion of food Transport protein- phosphoprotein, ferritin it helps in the transportation
- 28. Sources of Proteins Animal proteins, found in such food as eggs, milk, meat, fish, and poultry, are considered complete proteins because they contain all of the essential amino acids our bodies need. Plant proteins, found in vegetables, grains, and beans, lack one or more of the essential amino acids and make up incomplete proteins. However, plant proteins can be combined in the diet to provide all of the essential amino acids.A good example is rice and beans.
- 29. Making incomplete proteins complete Plant proteins can be combined in the diet to provide all of the essential amino acids. A good example is rice and beans. Each of these foods lacks one or more essential amino acids, but the amino acids missing in rice are found in the beans, and vice versa. So when eaten together, these foods provide a complete source of protein
- 30. people who do not eat animal products can meet their protein needs with diets rich in grains, dried peas and beans, rice, nuts, and tofu, a soybean product. Some health conditions, such as illness, stress, and pregnancy and breast-feeding in women, place an enormous demand on the body as it builds tissue or fights infection, and these conditions require an increase in protein consumption For example, a healthy woman normally needs 45 grams of protein each day. Experts recommend that a pregnant woman consume 55 grams of protein per day, and that a breast-feeding mother consume 65 grams to maintain health.
- 31. DIGESTION OF PROTEIN Mouth No digestion of proteins in the mouth Stomach The gastric juice is produced by the lining cells of the gastric mucosa.This juice contain inactive enzyme called pepsinogen. This enzyme is activated into pepsin by hydrochloric acid and break down protein into polypeptides. HCL acid also creates a conducive acidic environment for the digestion of protein. gastric mucus has the alkaline properties to protect the mucosa lining from corrosive acids. The food descends into small intestine
- 32. Digestion in the s.intestines The chyme in the s. intestine is exposed to the two digestive juices namely pancreatic juices and intestinal juice Pancreatic Juices- contain trypsin which acts on undigested protein from the stomach into polypeptides and further to dipeptides Intestinal juice- is produced by the glands on the walls of the duodenum and ileum; contain the enzymes like peptidases which finally converts the remaining polypeptides and dipeptides into amino acids
- 33. ABSORPTION All the digested amino acid passes through the epithelium and capillary walls of the intestine and enters the blood plasma. They are then carried away in the capillaries which join to form a large vein called hepatic portal vein. Once the amino acid reaches the general circulation they are taken to the parts of the body where they are needed/ used or stored.
- 34. FUNCTIONS of PROTEINS To replace worn out tissues in the body To provide raw materials for growth Provides ingredients in the formation of important body compounds e.g. haemoglobin, antibodies, enzymes Proteins regulate body fluids. In kwashiorkor patients reduced protein supply lead to fluid imbalance eg oedema In starvation conditions proteins provide energy which is needed.
- 35. Effects of proteins in excess Obesity Overweight Deficiency Kwashiorkor Underweight marasmus
- 36. FATS/LIPIDS Fats Fats are substances composed of lipids or fatty acids and occurring in various forms or consistencies e.g. oil. Chemical composition of fats Fats consist of carbon, hydrogen and oxygen, but they differ from carbohydrates in that the hydrogen and oxygen are not in the same proportions as in water.
- 37. Classification of fats Saturated or animal fat, contain mainly saturated fatty acids and glycerol, are found in milk, cheese, butter ,eggs, meat. These contribute to a lot of cancers and heart diseases. Unsaturated or vegetable fat, contain mainly unsaturated fatty acids and glycerol, are found in some margarine and in most vegetable oil.
- 38. Classification of fats cont.. Depending on the dietary requirements fats are of two kinds - essential and non-essential. Essential fats are those that are not synthesized by the body and have to be included in the diet e.g linoleic acid (Omega-3 fatty acid), linolenic acid (omega-6 fatty acid), arachidonic acid are polyunsaturated fatty acids. Non-essential fats are those that are synthesized by the body and are not necessary in the diet, example glycine.
- 39. Dietary sources of fats The dietary sources of fats include: milk, cheese, butter, eggs, meat, oily fish, margarine, and vegetable oils. FUNCTIONS OF FATS Fats provide energy- fats are the most efficient source of food energy because they provide a reservoir of energy for long term storage, which can be used if energy intake is restricted. Each gram of fat provides 9 calories of energy for the body compared to 4 calories per gram of carbohydrates and proteins. Fats build health cells- fats are a vital part of the membrane that surrounds each cell of the body. Without a healthy cell membrane, the rest of the cell cannot function properly.
- 40. Functions of fats cont.. Fats build brains- fats provide structural components not only of the cell membrane in the brain but also of the myelin.The fatty insulating sheath that surrounds each nerve fibre enables it to carry messages faster. Fats help the body use vitamins- vitamins A, D, E and K are fat soluble vitamins, meaning the fats in food help the intestines absorb these vitamins into the body.
- 41. Functions of fats cont.. Fats make hormones- Fats regulate the production of sex hormones, which explains why some teenage girls who are too thin experience delayed pubertal development and amenorrhoea. Fats provide healthier skin- one of the most obvious signs of fatty acid deficiency is a dry flaky skin. Fat acts as the body’s own insulation to help regulate body temperature (subcutaneous tissue). Thin people tend to be most sensitive to cold and obese people tend to be sensitive to warm weather.
- 42. Functions of fats cont.. Fats form of protective cushion for body organs- e.g kidneys, heart and intestines are cushioned by fats that helps and protect them from injury and hold them in place. These protective fats are the last to be used up when the body’s energy reserves have been depleted. Fats are pleasurable- besides being a nutritious energy source, fats add to the appealing taste, texture, appearance of the food and carry flavor.The foods containing fats provide a feeling of fullness after a meal as fat digestion is slow.
- 43. Digestion, absorption and metabolism of fats Digestion of fats begins in the duodenum and ends in the duodenum; the presence of fat in the small intestines stimulates the secretion of hormones cholecystokinin (CCK) and secretin from the duodenal cells. CCK signals the gallbladder to contract sending bile down the bile duct and into the duodenum were fat is emulsified by bile from the gallbladder. Secretin signals the pancreas to release pancreatic juice rich in pancreatic lipase. The pancreatic lipase converts the emulsified fats into fatty acids and glyceral.
- 46. Digestion, absorption and metabolism of fats cont.. Fatty acids and glycerol are then absorbed into lacteals of the intestinal villi and carried to the blood stream. It is then transported to the liver, fatty acids and glycerol circulating in the blood are used by the cells of organs and glands to provide energy and some are re- combined forming triglycerides
- 47. Daily requirement of fat The daily requirements of fat intake should be equal to 30% of your total day’s calories Effects of deficiency and excess of fat Fat deficiency has been linked with Atherosclerosis (hardening of the arteries), increased triglyceride levels and reduced high density lipoprotein (HDL) cholesterol levels restricting blood flow to the heart. Scaly skin rash and dermatitis.
- 48. Effects of deficiency and excess of fat cont.. Poor growth in children. Lower immune response. Neuropathy Visual disturbance. Excess fats in the body causes Obesity-is highly associated with the risk of type II diabetes, and gall bladder disease.
- 49. Conti…. Cardiovascular diseases such as hypertension, atherosclerosis etc.
- 50. Next Lecture UNIT TWO APPLIED NUTRITION ASSESSMENT METHODS
- 51. Assignment 1:ALL Nutrients are substances that are found in food which are meant to nourish the body. Nutrients include vitamins and minerals among others. QUESTION ONE: in a table form, discuss the different types of vitamins under the following headings: Vitamin Common Name Chemical name Daily requirement s Functions Effect of excess Effect of deficiency
- 52. Assignment:ALL QUESTIONTWO: in a table form, discuss the different types of minerals under the following headings: Minerals Name Daily requirements Functions Effect of excess Effect of deficiency
- 53. Assignment Two:ALL Discuss the different methods of food processing, stating the advantages and disadvantages with reference to the following headings: Preservation Cooking Storage
- 54. Reading assignment Anaemia is a condition in which there is lack enough healthy red blood cells to carry adequate oxygen to the body's tissues. Several causes have been identified that include, haemorrhage, osteoblastic disorders and nutrient deficiency. QUESTION: Discuss nutrient deficiency anaemia focussing on the causes, presentation (signs and symptoms), management and prevention.