Study Guide - Midterm 1 PDF

lOMoARcPSD|38834723 Study Guide - Midterm 1 Principles of Nutrition (Carleton University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Lauriane Londa ([email protected]) ...

lOMoARcPSD|38834723 Study Guide - Midterm 1 Principles of Nutrition (Carleton University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 Midterm 1 (BIOL 203) LESSON 1 (Introduction to Fundamental Nutrition) Nutrition o How an organism acquires food and uses the food to support all processes required for its existence. o Example: Plants are anchored to the ground by roots, they absorb nutrients from the soil solution, and direct it upwards towards the leaves. The developing leave and flower buds pick up the bulk of the nutrients, and together with photosynthesis, the plant has all it needs to grow. The Science of Human Nutrition o The study of the nutrients and other substances in food and the body’s handling of them. o Human nutrition is a fairly new science, which is why scientist often make new recommendations for healthy eating. o The sister discipline: Nutritional Genomics Food o Contains essential nutrients such as Carbohydrates, Lipids, Proteins, Vitamins and Minerals. o Food also contains non-nutrients such as fiber (promotes bowel health) and phytochemicals (function as antioxidants) Essential Nutrients o Essential Nutrients must be supplied by the diet because the human body cannot synthesis them. o Energy yielding nutrients: Carbohydrates, Lipids, Proteins o Non-energy yielding nutrients: Vitamins, Minerals, Water Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 Choosing Foods o Processed Foods vs Whole Foods o It’s been proven that whole foods are best for optimal health and nutrition o So why do we continue to choose processed foods: Convenience, emotional comfort, advertising, social network or beliefs. o Our beliefs do not always align with our behaviours (ex: healthy eating) Solution o 1) Learn about nutrition (a cognitive fix) o 2) Learn how to cook (a non-cognitive fix) requires proper cookware o By learning these two things, you will now have a vital life skill Cooking o Cooking can teach us many things including how to be organized, how to love, how to socialize, and food chemistry. o Food safety o Discipline (setting a time to prepare food and plan meals for the week) o Avoid food gadgets as they cost money and take up room in kitchen Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 LESSON 2 (Nutrient Standards and Guidelines) Dietary Reference intakes (DRI’s) o Reference values that are quantitative estimates of nutrient intakes which are used for planning and assessing diets for healthy people. o In the past: DRI’s were used to reduce the risk of deficiency diseases such as scurvies and beriberi disease. o Today, DRI’s are used to prevent chronic diet related diseases such as cardiovascular disease and Type 2 diabetes. Main objectives of DRI’s o Prevent deficiency diseases o Reduce risk of chronic diseases o Safety supplement use and fortification The 6 Nutrient Intake Standards o DRI’s for Most Nutrients  Estimated Average Requirement (EAR)  Recommended Dietary Allowance (RDA)  Adequate Intake (AI)  Tolerable Upper Intake Level (UL) - The first three target deficiency diseases, and the last one targets supplement use. o DRI’s for Energy and Macronutrients  Estimated Energy Requirement (EER)  Acceptable Macronutrient Distribution Ranges (AMDR) - These two exclusively target Carbohydrates, Lipids and Protein intake. Nutrient intake Standards o Nutrient standards differ by gender and life stage Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o Men have 10 life stages o Females have 16 life stages to include the periods of pregnancy and lactation o The periods of pregnancy and lactation are so taxing on the female human body that nutrient intakes must increase during this period Reading the DRI o mg/day: average daily requirement for each nutrient. o ND: No EAR or RDA for infants younger than 12 months because studies cannot be ethically conducted. o Estimated Average Requirement (EAR)  The average daily intake level of a nutrient to meet the needs of half (50%) of the healthy people in a particular life stage or gender group.  It is based on a diagnostic test that measures adequate amounts in the human body  It is a requirement, not a recommendation (because if it was a recommendation, 50% of the population would develop a deficiency disease) o Recommended Dietary Allowance (RDA)  The gold standard in DRI’s  The average daily nutrient intake level that meets the needs of 98% of healthy individuals in a particular life stage or gender group. o Adequate Intake (AI)  The average daily amount of a nutrient that appear sufficient to maintain a specific criterion (used when the RDA cannot be determined)  Based on intakes of a healthy group of people in a particular life stage and gender group.  The AI exceeds the EAR and lies somewhere near the RDA (but below the UL) o Tolerable Upper Intake Level (UL)  The maximum daily amount of a nutrient that appears safe for most healthy people  Above this level there is an increased risk of toxicity and eventually death  Most Canadians and Americans consume around 3400mg of salt (sodium) per day. The AI for sodium is 1500mg per day. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o Estimated Energy Requirement (EER)  The number of calories that maintain energy balance in a healthy person.  The EER is calculated for each individual person rather than a particular life stage or gender group.  It takes into account the individuals physical activity levels (PA), height in meters (HT), weight in kg (WT), age and gender. o Acceptable Macronutrient Distribution Ranges (AMDR)  The ranges of intakes for energy yielding nutrients that provide adequate energy and nutrients while reducing the risk of chronic diseases.  45-65% of energy intake should come from carbohydrates  20-35% of energy intake should come from Lipids (Fats)  10-35% of energy intake should come from Proteins  The recommendation applies to all healthy people (not to a specific life stage or gender group) Who uses DRI’s? o Registered Dietitians o Food industry (regulated by the CIFA) the Nutrition facts have been mandatory since 2007. It must include 13 core nutrients. o The food industry is interested in compliance reasons, but also for marketing. In order to make claims that a product is a good source of nutrient, the product must contribute to at least 15% of the daily recommended amount. Major Food Groups o Grains  Grains are considered seeds, as they contain a plant embryo, also known as the germ. The germ derives its nourishment from the carbohydrates stored in the endosperm. The seed is protected by the fiber rich outer layer called the bran.  The germ, endosperm and bran make up every seed, including grains.  Grains are rich in carbohydrates, fiber (only when grain is whole), vitamins (folate, thiamin, riboflavin, niacin and vitamin e) minerals (magnesium and iron). Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  The germ contains vitamins and minerals, the bran contains fiber, and the endosperm is mainly starch (used to make white bread)  Grains belong to the grass family. Grass leaves look very similar to the leaves of oat, wheat and rice.  Refined foods such as white bread and breakfast cereal have often lost most of their nutrients. Nutrients are added back through a process called enrichment. o Milk and alternatives  Includes milk and milk products that retain their content of the mineral calcium.  In Canada, these products are fortified with vitamins A and D.  They contain protein, vitamins B12, D and riboflavin, and mineral calcium.  Why is milk so nourishing? Milk was hammered out through the forces of evolution and engineered to be food for mammals. It made its first appearance in the evolutionary theater of life about 300 million years ago as a protective, nourishing skin excretion. We began drinking milk from other animals about 8000 years ago  Harold McGee describes cheese as “the intense concentrated expression of pastures, animals, of microbes and time.” And “one of the greatest human inventions of all time, which emerged about 5000 years ago.  The enzymes required to break down milk emerged 10,000 years ago.  As humans get older, we produce less of the enzyme required to digest the sugar found in milk (lactose) and this can lead to indigestion. o Meat and alternatives  Provide a good source of proteins, vitamins B6 and B12, as well as the minerals iron and zinc.  Meat (the flesh of goat, beef, pork or any other mammal), poultry (birds such as chicken, turkey or duck) and fish.  Alternatives include legumes, eggs, nuts and seeds (High in protein which is why they are grouped with meat). Legumes and nuts are also a great source of fiber and minerals such as magnesium and potassium  All alternatives have something in common. They are designed by nature to be food for embryo. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 - Legumes: Beans, peas, lentils etc. They share a similar floral structure and enclose their seeds in pods. Peanuts are also part of the legume family (they contain an embryo) which is why some people who are allergic to peanuts may also be allergic to other legumes but not to other nuts. For example, tree nuts (almonds, cashews, brazil nuts, chestnuts, macadamia) are not part of the legume family, however they all are a great source of protein. - Seeds: sunflower, pumpkin and even watermelon seeds are all a great source of protein, however unlike all other meat and alternatives, they do not contain a good source of other nutrients and may be high in salt. o Fruit and vegetables  Most important food groups  Contain carbohydrates, fiber, vitamins folate, A, C, and K, and minerals magnesium and potassium.  Fruits all contain seeds  Fruits: apples, apricot and banana, as well as tomato, zucchini, eggplant, squashes and bell peppers.  Vegetables include plant leaves (such as lettuce, spinach, kale and parsley) and root vegetables (such as carrots, turnups, fennel and parsnips) which are storage organs the plant uses for when energy is needed. The final members of this group, which reside outside of the pant kingdom are mushrooms. Food Guide o Target nutrient recommendation standards and divide them into 4 food groups. o Vegetables and fruits have the highest number recommended servings per day. o Hand reading serving size:  Palm: Good for measuring cooked protein (meat, fish, poultry)  Fist: Good for measuring cooked pasta, rice and vegetables  Thumb and pointer finger: good for measuring lipids (fats) such as mayo, oils and butter. o Seeds are ingested by animals and eliminated at some distance away from the maternal plant which allows the plants to move around in space. To encourage animals to dispute Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 their seeds they must place them inside of a nutritious sweet package as a way to encourage frequent visits. So, fruits, just like seeds, eggs and milk are natures perfect food. LESSON 3 Basic Chemistry and Organ Systems From Atoms to Compounds o 25% of the elements on the periodic table of elements are essential for life (not just human life but all living organisms) o Matter: is anything that takes up space, including the air that surrounds you. o Atoms: The smallest unit of matter is the atom.  The human body is composed of matter, representing 23 or more different elements and trillions of atoms.  Planet earth has 92 elements but a near infinite number of atoms.  Water is composed of 2 elements and 3 atoms. o Molecule: Atoms come together to form chemical bonds, in an ordered and stable arrangement. This arrangement is called a molecule. o Oxygen gas, Carbon Dioxide, Water and Glucose can all be referred to as molecules. o Compounds: When a molecule has 2 or more different elements, we generally call these compounds. Therefore, Carbon Dioxide, Water and Glucose are all compounds. Atoms and Their Subatomic Particles o Atoms are composed of subatomic particles: protons, neutrons and electrons. o The core of the atom (the atomic nucleus) is composed of positively charged protons and neutrons that carry no charge. o The atomic nucleus is surrounded by a cloud of negatively charged electrons (2 electrons). Under normal conditions, an atom has an equal number of electrons and protons, this balance maintains a neutral charge. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o What matters deeply is the number of electrons orbiting the outer shell. With the exception of hydrogen, all atoms on the periodic table of elements have 2 electrons orbiting the first inner shell. The second shell varies from 1-8 orbiting electrons. If an atom has a third shell, it can also carry between 1-8 electrons. Valence shells o The outermost shell is called the valence shell, and the electrons on that shell are called valence electrons. o The chemical behaviour of an atom is determined by the valence electrons. o Valence shells are completely filled when they have 8 orbiting electrons, with the exception of hydrogen whose valence shell is complete with just 2 electrons. o Atoms with full valence shells are chemically inert (They will not form chemical bonds). For example, helium, neon and argon are inert gases, and they have no desire to form chemical bonds. o Chemistry gold rule #1: An atoms quest is to have fully occupied valence shells. Bonds o Covalent bond: When incomplete shells pair up with other atoms to share or transfer other electrons with other atoms. This is why chemical bonds are formed. A covalent bond is the strongest of all bonds. For example, the table in front of you is made up of trillions of atoms in covalent bonds with other atoms (you cannot put your finger through the table and disrupt these bonds, that is the power of the covalent bond). o Ion: A charged atom or molecule o Ionic bonds: Some atoms have only a single valence electron, while others have 7. For atoms with only a single valence electron, they would require forming 7 chemical bonds with other atoms in order to fill their valence shell, however that is simply to much work. It is far more efficient to donate the outer electron to some other atom and this is exactly what happens. For example, table salt (sodium chloride) is the result of a bond between sodium and chlorine. Sodium has only a single valence electron, so the sodium atom transfers its electron to the chlorine atom. The chlorine atom, with 7 orbiting electrons, is happy to accept and is now called the chloride ion. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o Example: If you pour salt into a glass of water it will dissolve. If you place an eraser in a glass of water, it will not dissolve. The atoms that make up your eraser form covalent bonds. The sodium chloride bonds in salt are ionic bonds. Solutions o A homogeneous mixture of two or more compounds o The major component is called the Solvent o The minor component is called the Solute o When the solvent is water, we refer to it as an aqueous solution. The cells of our body are filled and bathed in an aqueous solution. o Blood is also an aqueous solution. It is composed of plasma and cells. The plasma in your blood is the solution that holds the nutrients from the foods you ate. o As blood rushes through the blood capillary (the smallest blood vessels), the plasma is forced out tiny openings and pools around the cells of your body. The cells can be anywhere in your body (from your ear lobe to your big toe). The cell is now bathed in this fluid and the fluid is a solution of water, with suspended nutrients in addition to other compounds. The cells can now take up these nutrients to meet their cellular needs. This is the final destination of the nutrients from the food that you eat. Electronegativity o Atoms form chemical bonds in order to share electrons and have filled valence shells. o Atoms in a molecule attract electrons to varying degrees (they differ in electronegativity) o Electronegativity is an atoms attraction for the electrons in a chemical bond. The more electronegative an atom, the more strongly it pulls shared electrons towards itself (like a selfish child who does not want to share) o Chemistry Golden Rule #2: The oxygen atom is very electronegative. In an oxygen- hydrogen bond, the shared electrons spend more time orbiting the oxygen atom. o Electrons, being negatively charged subatomic particles create a partially negative charge on the oxygen and a partially positive charge on the hydrogens. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 Polar molecules o Molecules with partial charges created by electronegative atoms. o They react with other polar molecules to form weak hydrogen bonds. o In a glass of water, individual water molecules are moving around forming these transient hydrogen bonds. You can put your finger in water and disrupt these bonds. o Water molecules are not only forming hydrogen bonds with each other, they can do this with other suspended polar solutes. For example, Glucose is a polar molecule that dissolves in water. An aura of partial charges surrounds the glucose molecule created by the oxygen atoms. When sugar is placed in water, water molecules form hydrogen bonds with the sugar molecules, thus sugar easily dissolves in water because of the hydrogen bonding party. o Proteins are also polar molecules and can dissolve in water. The water molecules are attracted to the aura of partial charges created by the oxygen atoms in the protein Solubility of Solutes o The solubility of a compound describes how easily it dissolves in a liquid solvent o Simple carbohydrates such as sugar dissolve in water, however other substances such as fats are insoluble and will not dissolve in water. o Starch does not dissolve in water because plants pack starch into tight dense granules.  Harrold McGee says:  “Heat the water up, and the granules swell as the threads of starch unfold. As they unfold, they form hydrogen bonds with water.”  “The granules unfold into an unorganized mess of water molecules and starch.”  “The temperature where starch becomes an amorphous network of starch and water intermingled is called the gelation temperature. At gelation, the starch water thickens.” Enzymes o Enzymes are proteins, and thus they easily dissolve in solution. o They help to digest food into smaller fragments. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o In the absence of enzymes, absorption of nutrients would be impossible. o Enzymes always have very specific three-dimensional structures that allow only certain compounds to bond. o An enzyme’s three-dimensional structure is the result of hydrogen bonds. This means we can easily change an enzymes shape. The pH Scale o The pH is a measure of the concentration of hydrogen ions (H+) o The pH scale ranges from 0-14 o Hydrogen ions interfere with hydrogen bonds o Enzymes in the digestive system are controlled by the pH of the solution in which they are suspended The pH of Fluids o pH is crucial to activating enzymes to facilitate digestion. o pH of saliva: 6.4 o pH of stomach: 1.0 o pH of small intestine: 8.0 o An enzyme that works to digest food in the mouth will not work in your stomach because of the change in pH causing enzyme to change shape. The Digestive System o A set of organs that work cooperatively to digest food and deliver nutrients. o A hollow tube from mouth to anus including the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus. The inside of the hollow tube is called the Lumen. o Transit time of food is anywhere from 24-72 hours o Cells, Tissues and Organs Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  We are multicellular creatures  Cells come together to form tissues  Tissues come together to form organs  Organs work cooperatively and form the organ system Types of Tissues 1. Epithelial Tissue  The lining of the entire alimentary canal is made up of epithelial cells.  Allows the smooth passage of food.  Synthesis and excrete enzymes for digestion.  Absorb nutrients 2. Connective Tissue 3. Muscle Tissue 4. Neural Tissue The Function of the Digestive System 1. Digestion 2. Absorption 3. Elimination o Functions are aided by the epithelial cells that make up the innermost lining of the digestive tract that produces and releases substances that facilitate digestion. o Substances released:  Enzymes (for digestion)  Hormones (for communication with other member of the system)  Mucus (to ease the passage and protect from irritating substances) Digestion o The Mouth and Stomach  The mouth and stomach perform both chemical and mechanical breakdown of food.  Muscular contractions churn food Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Mixed with stomach secretions food becomes chyme  Teaspoons of chyme at a time move slowly into the small intestines o The Architecture of the Small Intestine  Folds along the lumen have these tiny finger-like projections called Villi.  Each Villi’s is penetrated by two types of vessels: Blood vessel and lymph (lacteal) vessel.  The Villi is lined with epithelial cells, where each cell is bordered by microvilli, which helps nutrients absorb quickly.  While digestion is occurring, old epithelial cells fall off into the chyme and are digested. New cells replace the old ones (the small intestine has a very high turnover rate for its cells).  This is why the first sign of malnutrition is diarrhea, because if you can’t replace these epithelial cells, you can’t absorb food. Absorption o The Digestive System meets the Circulatory System  Absorption is the transfer of nutrients from the gastrointestinal tract into the blood or lymph vessels.  The epithelial cells that line the small intestine, absorb nutrients from the lumen and transfer them over to the blood capillaries (water soluble).  Fat however enters a different set of vessels, which are part of the lymphatic system. o The Accessory Organs  The accessory organs are intimately connected, as the small intestine is in direct physical contact with pancreases and gallbladder.  Substances produced in the liver, pancreases and gallbladder travel through tiny ducts and are released into the duodenum o Delivery  Nutrients absorbed from all over the intestines are delivered to the liver via the hepatic portal vein. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Inside the liver, the blood vessel splits into thousands of tiny capillaries giving the liver cells first dibs on the nutrients from your dinner plate. If you eat poorly, you have very little to offer these cells.  Then from the liver, this nutrient rich blood leaves to deliver nutrients to the rest of the cells in your body. Elimination o The process where solid waste is removed from the body.  The solid waste is eliminated through the large intestine  In the large intestine, waste will mingle with the friendly gut microbes.  The large intestine absorbs water and some minerals. o Gut Microbes  Microbes sustain themselves by feasting on fiber in addition to other compounds  400 species of bacteria resign in the large intestine  We can help out these microbes and improve the environment of our large intestine. Probiotic food contains live bacterial cultures, some of which thrive in the colon. The Circulatory System o The network of blood vessels  The heart acts as the pump blood moving throughout the system  The network of blood vessels include: - Arteries, Arterioles, Capillaries, Venules and Veins o Nutrient exchange between the blood and the cells on your body  When you get a paper cut, the cut splits open a tiny capillary and some blood escapes. The blood that pools to the surface of the skin contains the nutrients from the most recent meals you ate. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 LESSON 4 Carbohydrates The making of Food Calories o Plants package calories into carbohydrates. o Through photosynthesis, plants take 6 molecules of carbon dioxide from the air, extract water molecules from the soil solution and use the suns energy to rearrange these molecules into the glucose molecule. o Oxygen is then released into the air as a by-product of photosynthesis. o The suns energy is now stored inside the glucose molecule, more specifically, the energy is stored within the carbon hydrogen bonds of the glucose molecule. o When you need energy, your body breaks down glucose and release the energy stored within the carbon hydrogen bonds. o What is left of the glucose molecule after you’ve broken it down is carbon dioxide. The carbon dioxide you exhale are all that remain of glucose. Calories o Calories are found in carbohydrates, proteins and lipids (energy yielding nutrients) because they contain stored energy. o The energy stored in food is called a calorie. o Calorie is a unit that measures heat energy o Three types of calories 1. Small calorie 2. Big Calorie 3. Kilocalorie o We measure calories of food in Kilocalories. A kilocalorie is the heat energy needed to raise the temperature of 1000 grams of water by 1 degree. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o 1000 calorie = 1 Calorie = 1 Kilocalorie Energy yielding nutrients o Carbohydrates (glucose), protein and lipids store energy within their carbon hydrogen bonds. o Per gram, lipids provide far more energy than glucose and proteins. This is because per gram, lipids have a much greater abundance of carbon hydrogen bonds. o Per gram, Protein and carbohydrates have the same amount of carbon hydrogen bonds (4 kilocalories per gram) o How to measure calories: The Bomb Calorimeter Simple Carbohydrates o Monosaccharides: all have the same chemical formula (C6 H12 O6). The only difference between them are the arrangements of atoms and this difference results in varying levels of sweetness.  Fructose (Most sweet): Found in fruits and honey  Glucose (In the middle): Found in fruits and vegetables  Galactose (Least sweet): Found in milk and almost nowhere else o Of the three monosaccharides, glucose is the most important. It is the dominant sugar in the body and the dominant energy source for red blood cells and cells of the nervous system. Red blood cells rely almost exclusively on glucose o Disaccharides: These are pairs of monosaccharide (glucose is always present in the pair)  Glucose + Galactose = Lactose (Found in milk)  Glucose + Glucose = Maltose (Found in cooked sweet potatoes)  Glucose + Fructose = Sucrose (aka table sugar found in sugar cane and honey) o What is best table sugar, brown sugar or raw sugar? All three are made from sucrose which does not contain any toxic substances and is almost 100% carbohydrates. However raw and brown sugar are less processed and thus maintain more minerals and vitamins. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o Plants and animals rely on glucose, fructose and sucrose for energy to power growth, repair and reproduction. Single cell organisms such as microbes and bacteria also love sugars for the same reason. o Black teeth: Bacteria grow and thrive on the sugar stuck in the crevasses of the teeth. The bacteria produce acids that erode the enamel of your teeth and cause tooth decay. Alternative sweeteners o Non-Nutritive sweeteners  Synthetic compounds that are extremely sweet tasting compared to sugar but supply no energy per serving.  Ex: Sweet n low, Splenda and Equal  Stevia is a natural herbal sweetener o Sugar alcohols  Ex: Sorbitol, Xylitol and Mannitol  They are not fully absorbed by the intestinal Complex Carbohydrates o Made of hundreds or thousands of glucose molecules linked together in straight or branched chains. 1. Starch 2. Glycogen 3. Dietary Fiber o Starch is the storage form of glucose in plants. Our digestive system breaks down the starch into glucose units. o We then absorb glucose and build glycogen. Glycogen is the storage form of glucose in the body and provides us with a rapid release of energy when needed. o Fiber is built from a variety of monosaccharides and includes two types: Soluble and insoluble fiber. Fiber is the single most important complex carbohydrate for maintaining good health. Starch o Sources Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Plants store glucose in the form of starch. Stored in seeds such as grains and legumes and vegetables. o Types (most foods are a combination of the two)  Starch (Amylopectin): Quickly digested to glucose  Starch (Amylose): Slowly digested to glucose o Packaging  High starch potatoes are best for baked potatoes, mashed potatoes and French fries.  Low starch potatoes are best for salads Glycogen o Glycogen is the animal starch o We store glycogen in the liver and muscle cells. o When we exercise our muscles break down the glycogen to release glucose for energy. Fiber o Plant cell walls are like reinforced steel. The cement is the soluble fiber, and the steel beans are the insoluble fiber. o Soluble fiber  Dissolves in water  Fermented by the bacteria in the large intestines  Prized in the food industry for their thickening abilities. For example, Pectin’s extracted from fruits are used to thicken jams.  Slow gastric emptying and glucose uptake  Improve bowel health  Reduce the risk of cardiovascular disease, type 2 diabetes, obesity and colon cancer. o Insoluble fiber  Do not dissolve in water and do not form gels  They are not fermented in the large intestines  They provide bulk to stools and improve bowel movement Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  It is found in whole grains and many vegetables.  Promotes fast transit of stools and prevents diverticula Digestion of Carbohydrates o Starch and disaccharides in our foods get digested down to monosaccharides (mostly glucose) o The digestion of starch begins in the oral cavity with salivary amylase. The digestion continues in the small intestine with the following enzymes: Maltase, Sucrase, Lactase, and pancreatic amylase. o Glucose, fructose and galactose are absorbed by the epithelial cells that line the villi. They cross inside the epithelial cells and exit the other way and into the blood capillaries that penetrate each villus. Next, they travel to the liver where the monosaccharides will be converted into glucose and build glycogen. Diabetes o Type 1 Diabetes  Autoimmune disease  The immune system destroys the cells in the pancreas that synthesis insulin  Treatment: daily injections of insulin o Type 2 Diabetes (most common)  90% of people with diabetes have type 2  Caused by high sugar diet and causes the cells to become resistant or less responsive to insulin.  Poorly controlled type 2 diabetes leads to the pancreas shutting down o Gestational Diabetes  Occurs during pregnancy for some women  Caused by a poor diet Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 LESSON 5 Lipids Why are lipids necessary? o They enhance the flavour of food o Increase intestinal absorption of fat-soluble vitamins and phytochemicals. o We need at least 20 grams of fat to properly absorb fat soluble vitamins o Contribute to satiety (the feeling of fullness) o Once inside the body, fat works like body armor to protect the visceral and bones from breaking. Fat is a type of connective tissue that supports other tissues. Types of Fat o Visceral fat: A fatty apron that protects the abdominal organs. Too much visceral fat can increase one’s risk of cardiovascular disease. o Subcutaneous fat: (located below the surface of the skin) helps maintain body heat and cushions the body. Extra subcutaneous fat helps us as we age to protect us from breaking our bones. Lipids in the Body o On a cellular level, lipids are a major source of energy. o Fat provides more than twice the amount of energy than carbs and proteins o Lipids are the only form of energy that is stored for prolonged periods of time. o Lipids are the mains source of energy when we are at rest. o We store energy mostly as fat and not glycogen. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 Fat Cells Perform Triple Duty o While fat is an efficient form of energy storage, the downside is that we can store an unlimited amount. That means that fat cells can increase to more than 1000x their original size. Types of Lipids o Fatty acids  The basic building block of most lipids  Come together to form triglycerides and phospholipids o Triglycerides  Made up of 3 fatty acids o Phospholipids  Made up of 2 fatty acids o Cholesterol  The lipid that stands out because it lacks fatty acids, and because it is not used as a source of energy. Fatty Acids Length o A chain of carbon atoms attached to hydrogen atoms o Fatty acids contain a methyl group on one end of the chain and an acid group on the other. o They are insoluble and non-polar molecules. o Short chain fatty acids: 2-4 carbons long (ex: acetic acid) o Medium chain fatty acids: 6-12 carbons long o Long chain fatty acids: 14-24 carbons long Fatty Acids Shape o Some fatty acids are straight while some are bent. o The bend in some fatty acids is caused by the presence of double bonds. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o A fatty acid with no double bonds is said to be saturated with hydrogen atoms. Each carbon atom is paired with two hydrogen atoms (with the exception of the first and last carbons) o A fatty acid with one or more double bonds is said to be unsaturated. An unsaturated fatty acid has two neighboring carbon atoms forming a double bond. The double bond causes a kink in the chain (leaving the fatty acid to look broken). o A fatty acid with just a single double bond is called a monounsaturated fatty acid (MUFA) o If it has two or more double bonds, it is called a polyunsaturated fatty acid (PUFA) o Therefore, the level of unsaturation determines the shape. o The level of saturation also determines the behaviour of the lipid. For example, butter is principally composed of saturated fatty acids. These stick straight fatty acids, stack neatly and tightly against one another (this allows butter to remain solid at room temperature) o Oils are lipids that are liquids at room temperature. They are predominately composed of unsaturated fatty acids. These bend sticks compose a mess of unsaturated fatty acids, preventing the lipids from stacking tightly (leavings oils liquid at room temperature) o The carbon atom of the methyl group is considered the end of the molecule. This end is called the omega end. Essential Fatty Acids o Why all the fuss over omega 3 and omega 6 fatty acids? Remember the liver and muscle cells can store only a limited amount of glycogen, so what happens to those endless teaspoons of sugar? The liver converts them into fatty acids, so we can synthesis fatty acids but there is a catch. Our cells cannot place double bonds on positions 3 and 6 along the hydrocarbon chain, so consequently, these 2 fatty acids are essential nutrients. o Our bodies cannot synthesis them, therefore thy must be supplied by our diet. o Sources and function:  Omega 6 intake is easily reached through diet (even a poor one). Your cells convert linolenic acid (an omega 6 fatty acid) into arachidonic acid, and they become a part of the phospholipids in cell membranes. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Omega 3 intake is much harder to reach as few foods supply it and the ones that do are expensive. There are three types of omega-3 fatty acids: 1. Linolenic acid (high in walnuts) 2. DHA (Docosahexaenoic acid) 3. EPA (Eicosapentaenoic acid) - Fish, shellfish and fish oils are high in DHA and EPA. We require both DHA and EPA for proper brain function especially during infancy and for maintaining healthy arteries. DHA o Abundant in brain tissue and is essential for the growth and functional development of the brain in infants. o It is also essential for the maintenance of normal brain function in adults. o Plenty of DHA in the diet improves learning, while a deficit is associated with impaired learning. EPA o Helps to lower blood pressure, reduce blood clot formation, protect against irregular heartbeats and reduce inflammation. o It helps reduce the risk of cardiovascular disease. Trans Fatty Acids (TFA) o Trans Fats can kill you o Trans fatty acids come in two different shapes:  Cis configuration: If the hydrogen atoms next to a double bond on the same side of the chain (Bent shape)  Trans configuration: If the hydrogen atoms next to a double bond are on opposite sides (Straight shape) o With the exception of trans fat and butter, all trans fats are man-made through a process of hydrogenation: Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Unsaturated fatty acids are bombarded with hydrogen atoms. The fatty acids go from a cis to a trans configuration and the result is that unsaturated fatty acids behave like saturated fatty acids.  For example: Hard margarine is nearly 50% trans fats and is hard like butter. It contains unsaturated fatty acids, but these can now be stacked tightly to remain solid at room temperature.  Unlike butter, the advantage accorded to hard margarine was that they contained no saturated fat, hence reduce chances of heart disease and because of the orientation of hydrogen atoms, trans fats are more resistant to rancidity. Products made with trans fats have a longer shelf life. Hard margarine was sold as a healthier alternative to butter, however we later found out that trans fats cause coronary heart disease.  In 2003, Denmark banned the use of trans fats. Processed food found to have more than 2% trans fatty acids could result in a 2-year prison sentence.  This is how tub margarine came to be, today margarine contains very little, to no trans fats and is made from unsaturated fatty acids.  Since 2007, Health Canada has limited the trans-fat content of margarines to less than 2% of total fat. They also limited the trans-fat content of all other foods to less than 5%.  Trans fats must be included in the nutrition facts label Triglycerides o Most common lipid found in food. o 95% of what we eat is in the form of triglycerides and 99% of the fat in our bodies is stored as triglycerides. o Triglycerides can have varying amounts of saturated, Monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids o The fatty acids are attached to a glycerol molecule. o Fats and oils are triglycerides. Each fat or oil molecule contains 3 fatty acids anchored to a glycerol molecule. o The fatty acids of the triglyceride can be saturated, monounsaturated or polyunsaturated. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o Triglycerides vary in the number of saturated and unsaturated fatty acid chain they contain. Usually, one type predominates. PUFA’s o Oils with high amounts of polyunsaturated fatty acids turn rancid when deep fried o Under prolonged exposure to high heat the double bonds in fatty acid break down. o A hydrogen atom is lost, and the carbon atom now has an incomplete valence shell (terrible thing to happen) o This carbon atom with an incomplete valence shell is now unstable and will damage any neighboring molecule in an attempt to snatch an electron. This is what we call a free radical (an atom with an incomplete valence shell) o Rancid fat is unhealthy and has the potential to damage DNA. o Solution? Don’t deep fry food. o Saturated and monounsaturated fatty acids are more heat stable because they have fewer than one double bond. Chicken fat is 31% saturated fat (better than 61% fat in butter) making it a healthier way to deep fry if needed Phospholipids o Are diglycerides with a polar end attached to two non-polar hydrocarbon tails. o Partially water soluble o Differ by:  Length and shape of fatty acid  An additional compound that is joined to the phosphate o The most common phospholipid is lecithin o The partial solubility of phospholipids is partially responsible for the creation of life. They make up the cell membranes of all living organisms o Lipid Bilayer: Phospholipids make up the two layers of the cell membrane o Diglycerides are also key ingredients in the kitchen, being partially soluble, they act as emulsifiers. An emulsifier allows polar molecules like lipids to mix together with polar molecules without splitting. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 o For example, when making mayonnaise, the yolks phospholipids dig their hydrophobic tails inside the tiny droplets of oil to create an emulsion we call mayonnaise. Cholesterol o Entirely absent from plants, cholesterol is only found in the animal kingdom. o It is found in the foods that we east, such as, eggs, dairy, meat, fish and poultry. o It is a non-essential nutrient o The lipid that lacks fatty acids and is not broken down for energy. Instead, cholesterol has other important function in the body such as:  Vitamin D synthesis  Bile contains cholesterol and is crucial for the digestion of lipids  Cell membranes are studded with cholesterol  Cholesterol is necessary for synthesising estrogen and testosterone Digestion and Absorption of Lipids o Digestion  Digestion starts in the oral cavity as the warmth of the mouth begins to melt fat along with lingual lipase before reaching the stomach.  Chewing and churning mechanically breaks apart the fat  The bulk of chemical digestion of lipids is accomplished in the small intestine with the help of other accessory organs (liver, gallbladder and pancreases)  The epithelial cells of the small intestine release hormones to alert the accessory organs of the arrival of lipids.  Now that the accessory organs have received the message, the gallbladder squirts some bile into the small intestine. Bile contains cholesterol, salts and lecithin (a type of phospholipid)  The bile breaks down the large lipid globules into smaller bits called micelles. Pancreatic lipase, breaks down the triglycerides into free fatty acids and monoglycerides o Absorption Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723  Short and medium chain fatty acids can cross into the epithelial cells, go out the other end and enter the blood capillary and bee line for the liver  Long chain fatty acids cross into the epithelial cells and once inside they get repacked into what looks like a golf ball (chylomicrons) Lipoproteins o Chylomicrons are a type of lipoprotein o They contain triglycerides, protein, phospholipids, and cholesterol (everything inside these balls is non-polar) o There are 4 types of lipoproteins (they differ only in relative composition): 1. Chylomicrons  Packages in the epithelial cells of the small intestine  They transport dietary triglycerides and deliver them to fat and muscle cells, then they return to the liver. 2. VLDL (very low-density proteins)  A product of the liver. The liver transforms the extract teaspoons of sugar into fatty acids and packages them into VLDL’s (contain mostly triglycerides.  Once they have offloaded their triglyceride load, they are cholesterol rich remanence 3. LDL (low density lipoproteins)  Principally composed of cholesterol and deliver cholesterol to cells 4. HDL (high density lipoproteins)  Synthesised in the liver, they are designed to scavenge cholesterol from dead and dying cells and return to the liver  Mostly protein o LDL is the bad cholesterol o HDL is the good kind o Blood plasma contains varying amounts of all four of these lipoproteins, each one secretly containing lipids. Downloaded by Lauriane Londa ([email protected])  lOMoARcPSD|38834723 Cardiovascular disease (CVD) o Disease of the heart and blood vessels o Coronary heart disease is the most common o In 2013, was responsible for 25% of Deaths in Canada o CVD cost the Canadian economy 18 billion each year. o The path leading to CVD begins with inflammation of blood vessels. Substances like excess LDL cholesterol, excess glucose and toxins from cigarette smoke can cause irritation to blood vessels. This irritation increases the permeability of the arteries and elicits an inflammatory response. Cells of the immune system rush over in an attempt to repair this damage. These immune cells pick up LDL cholesterol and harden inside the lining of arteries (plaque). Depending on the location of the plaque buildup different organs can be affected including the heart, brain or kidneys. o A heart attack is the death of cardiac muscle tissue resulting in blockage of one or more coronary arteries. Coronary arteries supply oxygen rich blood to the heart muscle, however if they become blocked nutrients like oxygen are prevented from reaching the muscle cells that makeup the heart tissue and the cells die causing the heart to stop. o A stroke is the death of nervous tissue in the brain, usually resulting from a rupture or blockage of arteries to the head. How to reduce the risk of CVD? o Increase soluble fiber intake. The magic goo carries bile to the large intestine for elimination. Bile contains cholesterol. Every time bile is carried to the large intestine, you lower you chances of having CVD. Your large intestine is a drain, and the goal is to get cholesterol into that drain. If you don’t eat soluble fiber, the bile is re-absorbed into the liver and remains in circulation in your body (this is called enterohepatic circulation) o Limit fat intake (follow the AMDR) o Increase omega 3 fatty acid intake o If lifestyle and diet changes don’t work, people may need to be prescribed drugs such as satins Downloaded by Lauriane Londa ([email protected])