EPHE 155 Spring 2025 Lec5 Macronutrients Lipids Slides PDF

EPHE 155 Introduction to Nutrition: Concepts & Controversies Macronutrients Lipids University of Victoria, School of Exercise Science, Physical and Health Education Dr.Kimberly McQueen, BSc ND Email: kimberly [email protected] Learning Goals ❏...

EPHE 155 Introduction to Nutrition: Concepts & Controversies Macronutrients Lipids University of Victoria, School of Exercise Science, Physical and Health Education Dr.Kimberly McQueen, BSc ND Email: kimberly [email protected] Learning Goals ❏ Types and Sources: ❏ Identify the three categories of lipids: triglycerides, phospholipids, and sterols. ❏ List common food sources of lipids. ❏ Role in the Body: ❏ Explain the functions of lipids, including energy storage, cell structure, and hormone production. ❏ Digestion and Absorption: ❏ Describe how lipids are broken down, absorbed, and transported in the body. ❏ Health Implications: ❏ Discuss HDL, LDL cholesterol, and the effects of trans fats and omega fatty acids on health. ❏ Hydrogenation and Recommendations: ❏ Outline hydrogenation, its health effects, and dietary recommendations for lipid intake. Food Sources of Lipids Lekwungen not only refers to the language of the First Nations that reside, and have resided, in this area that Uvic lives but also refers to "the place where the herring fish are smoked." Neighbouring Nations would come here to harvest herring and smoke it before returning to their land. As we share this term together, we can be connected to the traditional use of the land and the provisions it has provided over time. "For indigenous people the land is not separate from all life that resides on it." Connecting Types of Lipids 3 categories of Lipids: 1. Triglyceride 2. Phospholipids 3. Sterols Triglycerides are the major form (95%) of lipids found in the body and food. The term Fat refers to triglycerides. We’ll see that the structure of triglycerides includes three (tri) fatty acids (fat) attached to a glycerol backbone (glyceride).  Fatty acids can differ from one Structure of Triglycerides: another in terms of length and in terms of saturation Triglycerides usually include a mixture of various fatty acids. Saturated vs Unsaturated Fatty Acids The Fatty Acids within Triglycerides Abbreviations: MUFA PUFA Triglycerides Depending on which fatty acids are incorporated into a triglyceride, the resulting fat will be: Softer (liquid) Harder Shorter-chain fatty Longer-chain fatty acids acids More unsaturated More saturated Melt at lower Melt at higher temperature temperature What’s in the name? Types of PUFAs Essential Fatty Acids Essential fatty acids ○ Linoleic acid and ○ Linolenic acid Functions ○ Make eicosanoids  Fatty Acid Composition of Fatty Acid Common Food Fats Composition of Common Food Fats EFAs and Inflammation ground flax seed, flax oil fish oil Recommendations for Omega 3 Fatty Acids Include fatty fish in a meal two to three times a week for a total of about 350 to 425 grams of fish per week Greater heart health benefits if fish is grilled, baked, or broiled You can also add ground flax seed, and flax oil to foods Potential Health Benefits of Fish Oil Also, Concussion care Food Sources of Omega 3 and Omega 6 Phospholipids: A phosphate with The phosphate They make up the two fatty acids makes it soluble in structure of the chains (vs the three water while the cell membrane - a of a triglyceride) fatty acids make it phospholipid soluble in fat bilayer Acts as an emulsifier Emulsifier: A substance that mixes with both fat and water  Some examples of Sterols are: Cholesterol, Sterols: Vitamin D (Cholecalciferol), the Sex Hormones (Estrogen, Progesterone, and Testosterone), and Cortisol and Aldosterone (part of our stress response) Cholesterol is a raw material that goes into making bile. The role of bile is essential in the emulsification of fats for absorption - including the absorption of the fat soluble vitamins. Cholesterol is a part of the myelin sheath ensuring efficient conduction of the nerve signal. Inserted in the cell membrane to help maintain its fluidity. Cholesterol is also a part of the plaques that can develop in the walls of arteries, as a part of atherosclerosis Trans Fats and Hydrogenation The Effects of Processing on Unsaturated Fats Hydrogenation of polyunsaturated fatty acids creates saturated and trans-fatty acids Creates a spreadable fat (margarine) Result is a more oxidation-resistant product that stores well Has a high smoke-point, so it is better suited to frying Trans Fats These fats are not made by the body Occur naturally in very small amounts in some foods: ○ Dairy foods, beef Pose risks to heart health ○ Raise LDL cholesterol ○ Lower HDL cholesterol ○ Produces inflammation in the body Digestion and Absorption of Lipids Digestion and Absorption of Lipids Digestion Absorption Mouth Some Fatty acids are now split from their glycerol backbone and Lingual lipase begins bat digestion. they combine with bile to form This plays a small role for adults but micelles. is more important for infants considering the fat content of breast The micelles (Bile) shuttles lipids milk (or formula). across the mucus layer. Stomach Small amount of fat begins digestion In the intestinal cell - the free fatty due to gastric lipase acids and monoglyceride are reassembled to triglycerides!! and Small intestine packaged into chylomicrons for Bile is excreted into the small transport into the lymphatic system, and then to the intestine to assist with fat digestion bloodstream. Pancreatic enzymes are secreted to split fat into small particles - Triglycerides in food are absorbed monoglycerides and free fatty acids with 98 percent efficiency Storage of Lipids The fats in food, the triglycerides, are carried by the chylomicrons to the fat depots in muscle, breast, under the skin and other areas. Fat cells are not inert but rather active in secreting hormone, some of which regulate appetite and influence body functions The number of fat cells we have is thought to be set during adolescence and then they expand or shrink depending on circumstances. Notable: Medium Chain Triglycerides (6-12 carbons) have special features. They are highly soluble in water, and do not require bile. They are absorbed via passive diffusion at the Small Intestine. They enter the portal circulation to the liver bound to albumin (a protein). They need no further packaging and can enter the mitochondria for Beta oxidation and so are more rapidly metabolized. Coconut oil is rich in Medium Chain Triglycerides, and often referred to as MCT oil. Short Chain Fatty Acids (SCFA) (fewer than 6 carbons) are a metabolic product of the work of gut bacteria on fibre. They are a main fuel source of intestinal cells. Some of their production is concentrated in the large intestine and this is a growing area of research as scientists look at how they contribute to intestinal health and their relation to IBS and IBDs. Lipids and Human Health Energy - more of an infinite storage capacity. Fats do not bring water alongside in storage and so they are “less bulky,” as compared to carbohydrates. Energy dense producing 9 calories per gram. Cell Membranes Brain and Nervous System -the human brain is nearly 60% fat Hormones and compounds Inflammatory mediators Fat soluble vitamins - A, D, E, K Contributes to satiety Fat in the Diet Important recommendations: Control portion sizes, particularly of fatty foods that can pack hundreds of Calories into just a few bites Diets lower in fat are generally lower in Calories and thereby help achieve and maintain a healthy body weight Diets low in saturated and trans fats may reduce the risk of heart disease Diets lower in fat, particularly saturated fat, may lower the risks of some cancers Diets with fewer Calories from fat have more room for health-promoting foods such as fruit, fish, legumes, low-fat milk products, nuts, vegetables, and whole grains Recommendations for Intakes of Fats for Healthy People Lipid Intake Targets Total Fat: AMDR is 20-35% as % of calories Saturated Fat: DRI Keep to less than 10% of Calories Trans Fat: WHO: less than 1% of total calories Cholesterol: DRI: the consumption of saturated fat, trans fat and cholesterol should be as low as possible Monounsaturated fatty Acids: Replace saturated fats with these and PUFAs, where possible PUFA (polyunsaturated fatty acids) the EFAs: Linoleic Acid (5-10% of total Calories) 17g per day for young men 12g per day for young women Linolenic Acid (0.6-1.2% of total Calories) 1.6g per day for men 1.2g per day for women  Definitions Saturated Fats = Triglycerides in which most of the fatty acids are saturated Monounsaturated = Triglycerides in which most of the fatty acids have one point of unsaturation. Polyunsaturated = Triglycerides in which most of the fatty acids have two or more points of unsaturation. Polyunsaturated fats are Essential Fatty Acids. Essential Fatty Acids = You must consume this type of lipid, your body cannot make it Trans Fats = a unique structure of fatty acids. A small amount are found in nature but largely formed by food processing Monoglyceride = products of digestion of lipids. Consists of glycerol with one fatty acid. Short Chain Fatty Acids (SCFA) = Fatty acids with fewer than 6 carbons Long Chain Fatty Acids (LCFA) = Fatty acids with 12 or more carbons Medium Chain Fatty Acids (MCT) = Fatty acids with 6-12 carbon Micelles = spheres of lipids that form in the aqueous medium of the small intestine; with the help of bile Fats = lipids that are solid at room temperature Oils = lipids that are liquid at room temperature This instead of that …