Lipids PDF

Lipids 16/10/2024 Developed by: Miss. Seham Alyami Updated by: Ms. Lena Bogari.  Introduction  Fat refers to the class of nutrients known as lipids.  The lipid classification includes: 1. Triglycerides (fats and oils) What is the difference between fa...

Lipids 16/10/2024 Developed by: Miss. Seham Alyami Updated by: Ms. Lena Bogari.  Introduction  Fat refers to the class of nutrients known as lipids.  The lipid classification includes: 1. Triglycerides (fats and oils) What is the difference between fats & oils? 2. Phospholipids 5% of total fat in food 3. Sterols.  The triglycerides predominate, both in foods and in the body. 4  Introduction The chemical name for fats and fat related compounds is lipids. Lipids are organic compounds, composed of a carbon with hydrogen and oxygen. Why fat provide more energy compared to carbohydrate? 5  Lipids Lipids are stored in the body as adipose tissue. The term lipids include:  Fats  Oils  Butter  Margarines and hidden fat. 6  1- Triglycerides In nutrition, the most important lipids are triglycerides (95%) of fat we eat. Triglyceride is made up of one glycerol attached to three fatty acids. It is the identity of the fatty acid present within a triglyceride that determines its physical characteristics, for example, the proportion of saturation and unsaturation will determine its hardness. 7 8  Types of fatty acids Fatty acids can be divided into three categories: – Saturated fatty acids – Example: meat, dairy, eggs, and coconut oil. – Monounsaturated fatty acids (MUFA) one double bond. – Examples: olive oil, peanut oil, canola oil. – Polyunsaturated fatty acids (PUFA) at least two double bonds – Example: Omega 3 or Linolenic acid and Omega 6 or Lenoleic acid both are essential. – Omega 6: vegetables oil from sunflower, corn, cottonseed, walnut, & soybean – Omega 3: Flaxseed and fish oil (Salmon) 9  Saturated Fatty Acids It is heavy & dense Solid at room temperature Most saturated fats are animal origin Unsaturated Fatty Acids It is less heavy & dense than saturated 10  Unsaturated Fatty Acids Omega-3 & omega-6 fatty acids: – When the first carbon double bond starts on the third carbon from the omega end, it is known as omega-3 fatty acid. – When the first carbon double bond starts on the sixth carbon from the omega end, it is known as omega-6 fatty acid. – If excluded from the diet a deficiency syndrome will develop such as retarded growth, skin lesions or dermatitis 12  Trans- Fatty Acids this result from a process called hydrogenation. Hydrogenation: some or all points of unsaturation are saturated by adding hydrogen molecules. Why??? 1- Longer shelf life (by protecting against oxidaition). 2- Alteration of the texture of food.( by making liquid vegetable oil more solid) – It is found in margarine & fast food. – Side effect: increase blood cholesterol and risk of heart disease. 13  2- Phospholipids Phospholipids : similar to triglyceride but having phosphate and choline instead of one of the fatty acid, which is attached to a glycerol molecule.  Lecithins type of phospholipids, and considered as emulsifier. Can be used as food additives. Example: egg yolk, soybean, liver, and peanuts. 14  Role of Phospholipids 1. Help fat soluble substances, such as: fat soluble vitamins to pass easily in and out of cell. 2. Keep fat suspended in the blood and body fluid.  3- Sterols Sterols made from plants called phytosterols, while made from animals are called zoosterol. Sterols play variety of important roles: 1. Membrane fluidity. 2. Cellular signaling. Category Example Sex hormones Testosterone, androgen and estrogen. Adrenal hormones Cortisol, cortisone, and aldosterone. Vitamins Vitamin D  Zoosterol. Cholesterol is one of the most significant zoosterol. The most well-known sterol are cholesterol. Foods derived from animal contain significant amount of cholesterol. Example: egg, meat, poultry, Seafood, and dairy product. Two types of cholesterol: A. Endogenous: Made in the body. B. Exogenous: Cholesterol from food. The liver manufacture cholesterol from fragments of : carbohydrate, protein, and fat. Cholesterol harmful effect is when it accumulate in the artery walls and contribute to the formation of plaque leading to cause atherosclerosis. Heart attacks and strokes. 17  Plant sterols Sterols other than cholesterol are naturally found in plants Phytosterol is a phytochemical that is structurally similar to steroid hormones. These compounds block the absorption of dietary cholesterol from the intestine and therefor may reduce blood cholesterol. FDA approved claims stating promote healthy cholesterol. Long term safety is still unknown. 18  Digestion of Fats Lipase: enzyme hydrolyze lipids. Note: Lingual lipase: at the bottom of the tongue. Phospholipids are digested similarly to triglyceride. Gastric lipase: from cells of stomach. Sterols usually can be Pancreatic lipase: from pancreas. absorbed as it’s. If fatty acids are attached they are Hydrolyzed off first. Goal of fat digestion: dismantle triglyceride into: Monoglyceride Fatty acids. Glycerol.  These small molecules the body can absorb. 19 Digestion of Fats Mainly milk fat. In this step infants benefit more compared to adults. 20 Digestion of Fats 21 Digestion of Fats Most action. 22 Absorption of Dietary Lipids Video  Absorption of Dietary Lipids Triglycerides are not soluble in water & thus cannot enter the bloodstream, which is mostly water. Within the small intestine: Bile + monoglycerides & free fatty acids = micelles. Monoglycerides & free fatty acids triglyceride which packed into chylomicron. Chylomicron: Triglyceride + cholesterol + phospholipids + proteins. 24  Absorption of Dietary Lipids Micelles allow the products of lipid digestion to travel to the brush board membrane. Once there, fats are absorbed into the epithelial cells of the intestine & bile is absorbed & transported by portal vein to the liver for reprocessing. Inside intestinal cells, monoglycerides & free fatty acids again form triglycerides, which then packed into chylomicron. This structure also forms within the intestinal cell & allows the products of fat digestion to enter the circulation. 25  Functions of fat in the body Provide energy (9kcal/g) Supply with essential fatty acids Major component of cell membranes Nourish skin and hair Layer of fat directly under the skin is important (why?) Insulate the body from extremes of temperature Protect vital organs Satiety, slowing down stomach emptying Carry fat soluble vitamins Transmission of nerve impulses. 26  Functions of cholesterol in the body Regulation of the fluidity of the cell membrane Facilitate the communication between cell and environment Limiting the leakage of Na and K across the membrane Synthesis of bile acid, needed for fat absorption Synthesis of hormones including sex hormones steroids and vitamin D 27  Health issues in lipids Amount of fat: too much fat supplies excess calories that are stored in adipose tissue, over time adding to body weight. Leading to health problems such as obesity, diabetes, heart disease and hypertension. Type of fat: high amount of saturated fat and cholesterol promote atherosclerosis. On the other hand, fat in olive oil, vegetable oils and fatty fish if eaten in moderation can decrease risk of heart disease. Balance is key! 28  Where’s the Saturated Fat in Foods? Examples of foods with saturated fat are: Beef Lamb Poultry, especially with skin Lard and cream Butter Cheese –some types- Ice cream Coconut Palm oil Adopted from: American Heart Association website. 29  Lowering Blood Cholesterol Levels Consume less saturated and trans fats Consume less cholesterol Make smart, informed food choices – Limit or consume processed food in moderation – Eat at least two servings of fish per week – Consume more plant foods – Consume antioxidants and phytochemicals – Garlic may help lower cholesterol – Flavonoids may help prevent LDLs from oxidizing Exercise. 30 Dietary recommendations of fat in the diet An acceptable macronutrient distribution range: – Total fat: 20-35%of total calorie intake – Polyunsaturated fat: Omega 6 fats: 5-10% of total calories Omega 3 fats: 0.6 – 1.2% of total calories – Saturated fat: less than 10% of total fat – Cholesterol: 300mg/day or less – Trans fat: try to avoid. 31  Class Activity How to Read Fat of Food Labels 32 Adopted from: The British Nutrition Foundation. 33 International recommendations for fat content in food products per 100g for solid foods Low: Total fat: < 3g, Saturated fat: < 1.5g Medium: Total fat: 3-17.5g, Saturated fat: 1.5-5g High: Total fat: > 17.5g, Saturated fat: > 5g 34  Evaluate??? High in total fat and moderate in terms of saturated fat  Evaluate??? medium in total fat and Suitable Claim: Saturated fat free International recommendations for fat content in food products per 100g for liquid foods/drinks Low: Total fat: < 1.5g, Saturated fat: < 0.75g Medium: Total fat: 1.5 - 8.75g, Saturated fat: 0.75 – 2.5g High: Total fat: > 8.57g, Saturated fat: > 2.5g 37 Evaluate??? Medium Evaluate??? Low Evaluate??? High Ranch dressing  REVIEW: How to calculate personal daily value for fat? Suppose your energy intake is 1800 calories per day and your goal Calculate an acceptable range from the following: Total fat : (calories + grams) Polyunsaturated fat: (calories) Saturated fat: (Calories) 41  What about Omega 3 supplements?? Must be used under medical supervision. Because high intake of omega 3 can cause: Increase of bleeding time, interfere with wound healing, raise LDL cholesterol, and suppress Immune function. Thank you Any Questions? 43