Lecture 13 Nutritional Requirements

Lecture 13 Nutritional Requirements The Nutrient and Nutrition. Classes of nutrients: carbohydrates, fats, proteins, vitamins, water, minerals. Function, sources and deficiency/toxicity of major vitamins and minerals.

The Nutrient and Nutrition Humans are heterotrophs, organisms that cannot produce their own food. Heterotrophs must ingest, or take in, food. At least 95% of the species of organisms on earthall animals, all fungi, and most protists and bacteriaare heterotrophs. Food provides the heterotrophs or “other-feeders” with two things: (1) energy, and (2) the raw materials to build the substances they need. The energy in food is described in units called calories, or properly kilocalories (thousands of calories, or kcal). The raw materials are nutrients. Nutrients are the raw materials, which provide the essential matter and energy for life. Nutrition refers to all the processes by which living organisms obtain and use these nutrients.

Classes of Nutrients There are six classes of nutrients: (1) carbohydrates, (2) fats (lipids), (3) proteins, (4) vitamins, (5) minerals, and (6) water. These are the substances, in fact, that make up most of our body. Assuming that you are a proper weight for your height, your body is made up of about 60% water, and about 20% fat. The other 20% is mostly protein, carbohydrate, combinations of these two substances, and two major minerals found in your bones: calcium and phosphorus. Other minerals and vitamins make up less than 1% of you. Energy Nutrients: Carbohydrates, Lipids and Proteins Carbohydrates, lipids, and proteins are organic (carbon-containing) compounds and are used by your body as a source of energy, or kilocalories. They are, therefore, often referred to as the energy nutrients. Proteins, however, are not a preferred energy source. In addition, these three organic compounds are used as building blocks for growth and repair, as well as to produce other substances your body may need. Your body does not obtain energy from vitamins, minerals, or water. Energy-Rich Carbohydrates Fresh fruits, whole grains, and vegetables—especially legumes such as peas and beans—provide abundant complex carbohydrates . The body breaks the starch in these foods into glucose, your primary source of energy. These foods also provide essential vitamins and fiber. Eating foods high in soluble fiber helps lower one's cholesterol level and may reduce the risk of heart disease. A diet high in insoluble fiber helps prevent constipation. Foods rich in processed carbohydrates such as white flour, refined sugar, and corn syrup are sometimes said to be lull of "empty calories/' This is a way of saying that these foods provide little in the way of vitamins or fiber. You may have noticed breads and other grain-based foods labeled as "gluten-free." Gluten is a protein found in wheat and many other grains. An estimated 1 percent of the population has a genetic disorder called celiac disease, in which gluten causes an autoimmune reaction that harms the small intestine's villi. Celiac disease is treated by eliminating gluten from the diet. Good Fat, Bad Fat Your body uses lipids to build cell membranes, as energy stores, and as a reservoir for fat-soluble vitamins. Linoleic acid and alpha-linolenic acid arc essential fatty acids, meaning the human body needs them but cannot make them, so they are required in the diet. Both are polyunsaturated fats; their long carbon tails include two or more double bonds. Unsaturated fats are liquid at room temperature. We divide the polyunsaturated fatty acids into two categories: omega-3 fatly acids and omega-6 fatty acids. Omega-3 fatty acids, the main fat in oily fish such as sar dines, seem to have special health benefits. Studies suggest that a diet high in omega-3 fatty acids can reduce the risk of cardiovascular disease, lessen the inflammation associated with rheumatoid arthritis, and help diabetics control their blood glucose. Oleic acid, the main fat in olive oil. may also have health benefits. It is monounsaturated, which means its carbon tails have only one double bond. A diet in which olive oil is substituted for saturated fats helps prevent heart disease. Dairy products and meats are rich in saturated fats and cholesterol. Overindulging in these foods increases one's risk for heart disease, stroke, and some cancers. Trans fatty acids, or trans fats, are manufactured from vegetable oils. However, they have a molecular structure that makes them even worse for the heart than saturated fats. All food labels are now required to show the amounts of trans fats, saturated fats, and cholesterol per serving. Body-Building Proteins Amino acids are building blocks of proteins. Your cells can make some amino acids but you must get eight essential amino acids from food.Most proteins in meat are "complete," meaning their amino acid ratios match a human's nutritional needs. By contrast, most plant proteins are "incomplete," meaning they lack one or more amino acids essential for the human diet. The American Dietetic Association states that, with careful planning, a vegetarian diet can provide all essential nutrients for people in any stage of life. To obtain all the required amino acids from plant sources alone, one must combine foods so that the amino acids missing from one component are present in some oth ers. As an example, rice and beans together provide all necessary amino acids, but rice alone or beans alone do not. You do not have to eat the two complementary foods at the same meal, but both should be consumed within a 24-hour period. Vitamins Vitamins are organic molecules required by the body in small amounts for metabolism, to protect health, and for proper growth. Vitamins perform functions such as helping your body to form red blood cells and to unlock the energy in carbohydrates, fats, and proteins. Although required only in small amounts, each of the 13 different vitamins plays a vital role in your body (Table). Many, such as the B vitamins, are used for the synthesis of coenzymes, small molecules that help enzyme work. For example, niacin and riboflavin, two of the B vitamins, are used to make the coenzyme NAD (nicotinamide adenine dinucleotide), and FAD (flavin adenine dinucleotide), which function in cellular respiration. The 13 well-identified vitamins are classified according to their ability to be absorbed in fat or water. The fat-soluble vitamins—A, D, E, and K—are generally consumed along with fat-containing foods, and because they can be stored in the body's fat, they do not have to be consumed every day. The water-soluble vitamins—the eight B vitamins and vitamin C—cannot be stored and must be consumed frequently, preferably every day (with the exception of some B vitamins).

Functions and Sources of Major Vitamins Important to Humans ____________________________________________________________________________________ Vitamin Major Function Common Source Deficiency ____________________________________________________________________________________ 1. Vitamin A or Formation of visual pigment Green or yellow Night blindness Maintenance of epithelia cells fruits & vegetables Dry skin Stimulates new cell growth Eggs Growth failure Delays senility Milk Liver ____________________________________________________________________________________ 2. Vitamin B1 or Necessary for growth, fertility, Whole grain cereals Mental confusion Thiamine and lactation Leaf green vegetables Loss of muscular Essential for normal nerve function Nuts coordination Meats Organ meats Eggs ____________________________________________________________________________________ 3. Vitamin B2 or Essential for carbohydrate Liver Dry skin Riboflavin metabolism Milk Cracked lips Serves in the maintenance of Meat Sensitivity to mucous membranes Dark green vegetables light Essential for normal healthy skin Whole grain Cereals ____________________________________________________________________________________ 4. Vitamin B3 or Coenzyme in the release of Liver Skin problem Niacin or energy from nutrients Poultry Diarrhoea Nicotinic acid Meat Mental confusion Whole grain Depression Cereals Mental Nuts disturbances ____________________________________________________________________________________ 5. Vitamin B6 or Necessary for the absorption & Whole grains Skin disorders Pyridoxine metabolism of amino acids Cereals Cracks at the Formation of red blood cells Bread mouth corners Fat metabolism Liver Convulsions Spinavh Dizziness Green bean Nausea Banana Anemia Kidney stones ____________________________________________________________________________________ 6. Vitamin B12 or Necessary for the formation of Liver Pernicious anemia Cobalamin nucleoproteins & proteins Kidney Necessary for the formation of Meat red blood cells Fish Necessary for functioning of the Eggs nervous system Milk ____________________________________________________________________________________ 7. Folic acid or Coenzyme needed for forming Organ meats Birth defect folacin body protein and hemoglobin Leafy green vegetables (neurological (B Vitamins) Legumes disorders) Nuts Anemia Whole grains Yeast ____________________________________________________________________________________ 8. Pantothenic acid Energy metabolism Abundant in many Rare (B Vitamins) foods ____________________________________________________________________________________ ____________________________________________________________________________________ Vitamin Major Function Common Source Deficiency ____________________________________________________________________________________9. Biotin Coenzyme in carbohydrate & Liver Rare (B Vitamins) fat metabolism Peanuts Plays a role in the formation of Cheese fatty acids Eggs ____________________________________________________________________________________ 10. Vitamin C or Formation & maintenance of Citrus fruits Scurvy Ascorbic acid collagen Other fruits Poor wound healing Formation of bones & teeth Broccoli Enhances the absorption of iron Tomatoes from foods of vegetable origin Green leafy vegetables ____________________________________________________________________________________ 11. Vitamin D Necessary for normal bone Eggs Rickets (bone (sunshine vitamin) formation Liver deformation) Necessary for retention of calcium Fish & phosphorus in the body Vitamin-D fortified milk ____________________________________________________________________________________ 12. Vitamin E Preventing the oxidation of Vegetable oils Rare vitamin A and fats Wheat germ Plays some role in forming Liver red blood cells & muscle Leafy green vegetables ____________________________________________________________________________________ 13. Vitamin K Necessary for the coagulation of Alfalfa Hemorrhage blood (blood clotting) Fish livers Leafy green vegetables Soybean oil Liver ____________________________________________________________________________________ Minerals Minerals are inorganic substances and are transported aroud the body as ions dissolved in the blood and other body fluids. Your body uses a variety of minerals that perform a variety of functions (Table). Calcium, for example, does many jobs, including making up a part of the structure of your bones and teeth and helping your blood to clot. Sodium plays a key role in regulating the fluid balance within your body. Magnesium is an important player in the process of releasing energy from carbohydrates, fats, and proteins. Functions and Sources of Major Minerals Important to Humans ____________________________________________________________________________________ Mineral Major Function Common Source Deficiency ____________________________________________________________________________________ 1. Calcium (Ca) Component of bone & teeth Milk Osteoporosis Necessary for blood clotting Fish Necessary for nerve transmission Necessary for muscle action ____________________________________________________________________________________ 2. Phosphorus (P) Component of bone & teeth Milk Rare Necessary for energy transfer (ATP) Meat Component of nucleic acid Soft drinks (DNA & RNA) ____________________________________________________________________________________ 3. Magnesium (Mg) Necessary for bone formation Wheat bran Weakness Necessary for muscle & Green vegetables nerve function Nuts ____________________________________________________________________________________ 4. Sodium (Na) Necessary for maintaining Salt Nausea osmotic pressure Seafood Vomiting Plays role in nerve transmission Processed food Muscle cramps ____________________________________________________________________________________ ____________________________________________________________________________________ Mineral Major Function Common Source Deficiency ____________________________________________________________________________________ 5. Chlorine (Cl) HCl synthesis Salt Rare Necessary for maintaining Processed food osmotic pressure Plays role in nerve transmission ____________________________________________________________________________________ 6. Potassium (K) Necessary for maintaining Fruits Heart irregularities osmotic pressure Vegetables Muscle cramps Plays role in nerve transmission Anemia ____________________________________________________________________________________ 7. Iron (Fe) Hemoglobin synthesis Liver Anemia Oxygen transport Meat Bread Cereals ____________________________________________________________________________________ 8. Zinc (Zn) Component of many enzymes Seafood Skin rash Liver Poor growth Meat hair loss Whole grain ____________________________________________________________________________________ 9. Iodine (I) Thyroid hormone production Iodized salt Goiter Seafood ____________________________________________________________________________________ 10. Fluorine (F) Strengthener of teeth Fluoridated water Increased risk of Tea dental caries ____________________________________________________________________________________ 11. Copper (Cu) Iron metabolism Liver Anemia Component of many enzymes Cocoa Whole grain ____________________________________________________________________________________

Water A large portion of all living things is water. For example, about 70% of your body mass is water. Water has many functions in living organisms. The main ones are: 1. Water provides the medium in which all the body’s reactions take place. 2. It aids in the digestion and absorption of food. 3. It is a medium of transport, through arteries and veins, with an organism. 4. It even lubricates your joints and cushions organs such as the brain and spinal cord. 5. It helps in the excretion of harmful by-products of metabolic processes. 6. It aids in the regulation of heat loss. 7. The atoms that make up water molecules are also held within the bonds of the energy molecules. These atoms are key players when bonds are broken (by hydrolysis) or formed (by dehydration synthesis) in these molecules.

Food as Fuel: Calories Count Like all animals cells, human cells require energy to carry out biochemical, mechanical, and transportation tasks. Cells derive energy from the chemical bonds in fats, carbohydrates, and proteins an animal eats, digests, and absorbs; any energy an animal does not immediately use can be stored as the carbohydrate glycogen in the liver or muscles or as fat in fat cells. * Food energy is usually measured in kilocalories (kcal), also called Calories (Cal). * A large apple contains about 70 Cal worth of energy-producing compounds; and jogging 1.6 km (1 mile) burns about 100 Cal of stored energy. * The food energy in a slice of bread could bring a liter of water to a boil, and a pound of body fat has enough energy to bring 52 liters (13 gal) to a boil! * Each person has a minimum daily energy requirement that varies with age, sex, body size, activity level, and other factors. In general, a normally active female college student needs around 1,800-2,000 Cal a day to fuel her total metabolic needs; a male college student needs about 2,200-2,500 Cal. Carbohydrate and protein each provide about 4 Cal/g, while fat provides more than twice as much, or 9 Cal/g. * A person would have to run for about 30 minutes, for example, to burn off the calories in a cheeseburger. When an animal’s food intake exceeds its energy needs, the inevitable result is an increase in amount of leftover energy stored as body fat. This basic biological fact means that the secret of weight control lies in taking in only as many kilocalories as the body needs for fuel. To stay trim and fit with a desirable percentage of body fat and healthy, efficient heart and lungs, a person should perform continuous, rhythmic, aerobic exercise (such as walking, jogging, swimming, or cycling) three to five times per week for 15-60 minutes, depending on the intensity of the exercise. Sound weight-loss diets combine calorie reductions, primarily through diminished intake of sugar and fat, with increased physical activity. Some dieters find it useful to focus on the biological function of eating: to take in the nutrients the body needs for energy, maintenance, and repair. As one wise saying goes, “Eat to live, don’t live to eat”. “Eat less to eat more”. Body Mass Index (BMI) The body mass index (BMI), or Quetelet index, is a measure for human body shape based on an individual's weight and height. Body mass index is defined as the individual's body mass divided by the square of their height. The formulae universally used in medicine produce a unit of measure of kg/m2. BMI

The correlation between the BMI number and body fatness is fairly strong however the correlation varies by sex, race, and age. 1. At the same BMI, women tend to have more body fat than men. 2. At the same BMI, older people, on average, tend to have more body fat than younger adults. 3. Highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness. BMI is only one factor related to risk for disease, For assessing someone's likelihood of developing overweight- or obesity-related diseases 1. The individual's waist circumference (because abdominal fat is a predictor of risk for obesity-related diseases). 2. Other risk factors the individual has for diseases and conditions associated with obesity (for example, high blood pressure or physical inactivity). How to read food labels

Start here: Note the size of a single serving and how many servings are in the package.
Check total calories per serving. Look at the serving size and how many servings you’re really consuming. If you double the servings you eat, you double the calories and nutrients, including the Percent Daily Value (% DV).

Limit these nutrients: Remember, you need to limit your total fat to no more than 56–78 grams a day — including no more than 16 grams of saturated fat, less than two grams of trans fat, and less than 300 mg cholesterol (for a 2,000 calorie diet).

Get enough of these nutrients: Make sure you get 100 percent of the fiber, vitamins and other nutrients you need every day.

Quick guide to % DV: The % DV section tells you the percent of each nutrient in a single serving, in terms of the daily recommended amount. As a guide, if you want to consume less of a nutrient (such as saturated fat, cholesterol or sodium), choose foods with a lower % DV — 5 percent or less is low. If you want to consume more of a nutrient (such as fiber), seek foods with a higher % DV — 20 percent or more is high.

Malnutrition

Malnutrition refers to insufficient, excessive, or imbalanced consumption of nutrients by an organism. In developed countries, the diseases of malnutrition are most often associated with nutritional imbalances or excessive consumption. Although there are more organisms in the world who are malnourished due to insufficient consumption, increasingly more organisms suffer from excessive over-nutrition; a problem caused by an over abundance of sustenance coupled with the instinctual desire (by animals in particular) to consume all that it can.

Plant Nutrition

Plants need nutrients for their growth. They are the source of carbohydrates (fiber and grain), protein (lentils) and fat (seeds). Some elements are directly involved in plant metabolism. Plant nutrients can be divided as: * Macro-nutrients: essential for plant growth and development. And large amount is needed. Macronutrients are; Nitrogen, Phosphorus, Potassium , Calcium , Magnesium, Sulfur Silicon * Micro-nutrients: good for plant growth. Trace amount is needed. Micronutrients are: Chlorine, Iron, Boron, Manganese, Sodium, Zinc, Copper, Nickel, and Molybdenum.

Review Questions 1. Define nutrient and nutrition. 2. What are the six classes of nutrients? 3. Which nutrients are called energy nutrients? Why? 4. Describe the importance of vitamins, with example, in our diet. 5. Describe the functions of calcium, potassium and magnesium. 6. Why is water so important to animals? 7. List five vitamins with their major function and their source. What are signs and symptoms of their deficiency? 8. List five minerals with their major function and their source. What are the signs and symptoms of their deficiency? 9. What is BMI. Calculation of BMI with given weight and height. 10. Why BMI index is important to know. 11. How you can calculate your need for calories/day? 12. What is malnutrition? 13. What types of nutrients does a plant need for? Write with examples. 14. Describe how you will read a food label.