Nutrition and Health: Macronutrients - Lipids Lecture - AHDT 1211 Lec4

Nutrition and Health: Macronutrients - Lipids Dr Hanapi Kulliyyah of Allied Health Sciences CLASSIFICATION OF FAT  The Lipids: Fats and Oils Lipids: a family of compounds that includes triglycerides (fats and oils), phospholipids, and sterols (cholesterol). Fats: lipids that are...

Nutrition and Health: Macronutrients - Lipids Dr Hanapi Kulliyyah of Allied Health Sciences CLASSIFICATION OF FAT  The Lipids: Fats and Oils Lipids: a family of compounds that includes triglycerides (fats and oils), phospholipids, and sterols (cholesterol). Fats: lipids that are solid at room temperature. Oils: lipids that are liquid at normal room temperature. Characterized by their insolubility in water. Dietary fat consists primarily of triacyglycerol (98%), and smaller amount of phospholipids and sterols.  Fatty Terms Triglycerides: the major class of dietary lipids, including fats and oils. A triglyceride is made up of three units of fatty acids and one unit of glycerol. Fatty acids: basic units of fat composed of chains of carbon atoms with an acid group at one end and hydrogen atoms attached all along their length. Glycerol: an organic compound that serves as the backbone for triglycerides. Triglyceride Triglyceride  Classification of Fats – Faturated and unsaturated Saturated Monounsaturated Polyunsaturated Animal Fats Olive Oil Corn Lard Canola Oil Soybean Butter Peanut Cottonseed Palm Avocado Safflower Palm Kernel Sunflower Coconut Fish Oils Classification of Fats - Fatty Acids Chain Vary in Carbon Chain Length – Most naturally occurring fatty acids contain an even number of Carbons – LONG CHAIN: 12-24 carbons Meat, Fish, Vegetable Oils – MEDIUM CHAIN: 6-10 carbons Dairy Products – SHORT CHAIN: < 6 carbons Dairy Products  Saturated fatty acid Fatty acid carrying the maximum possible number of hydrogen atoms (having no points of unsaturation). Saturated fats are found in animal foods like meat, poultry, and full-fat dairy products, and in tropical oils such as palm and coconut.  Saturated fatty acid The body can synthesis saturated fatty acids (i.e. Palmitic acid (16C:0) to provide an adequate level needed for their physilogical and structural functions. It is neither possible nor advisable to achieve zero percent of energy from saturated fatty acids in typical whole foods diets. This is RNI for dietary fat (for general adults) is set at 25 – 30% of energy.  Unsaturated fatty acid Fatty acid with one or more points of unsaturation. Unsaturated fats are found in foods from both plant and animal sources. Unsaturated fatty acids are further divided into monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA).  Monounsaturated fatty acids Fatty acid containing one point of unsaturation, found mostly in vegetable oils such as olive, canola, and peanut. The monounsaturated fatty acids are important in the membrane structural lipids particularly nervous tissue myelin. The majority of dietary monounsaturated fatty acids is oleic acid (18:1 n-9). The body can synthesis Oleic acid (18:1) but we also need it from diet  Polyunsaturated fatty acid Abbreviated PUFA, a fatty acid in which two or more points of unsaturation occur, found in nuts and vegetable oils such as safflower, sunflower, and soybean, and in fatty fish.  Essential Fatty Acid (EFA) Fatty acid that cannot be synthesized in the body in amounts sufficient to meet physiological need. Human body can make fat except these two (reason?) Linoleic acid (the 18-carbon omega-6 fatty acid), linolenic acid (the 18-carbon omega-3 fatty acid): polyunsaturated fatty acids, essential for human beings.  Essential Fatty Acid BUT! Human body can USE Linoleic acid (from the diet) to make other members of the omega-6 family— such as the 20-carbon polyunsaturated fatty acid –to form arachidonic acid – Arachidonic acid is involved in the regulation of gene expression. Human body can also USE Linolenic acid (from the diet) to make other members of the omega-3 family— such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)  Essential Fatty Acid Omega-3 fatty acids, found in fish oils, offer a protective effect on health. – Interest in fish oils was first kindled when someone thought to ask why the Eskimos of Greenland, who eat a diet very high in fat, have such a low rate of heart disease. – Blood clot formation, inflammation (e.g. arthritis, asthma), irregular heart rhythm and cancer also seem to be beneficially affected by DHA and/ or EPA.  Omega-6 fatty acids Linoleic – Precursor to ARACHIDONIC ACID – Found in vegetable oils and meat LINOLEIC ARACHIDONIC 18 Cs 20 Cs  Omega-3 fatty acids Linolenic Acid – Precursors of DHA (Docosahexaenoic acid) EPA (Eicosapentaenoic acid) – Fish and marine foods excellent food source LINOLENIC ACID DHA/EPA  Trans Fatty Acid Trans fatty acid: a type of fatty acid created when an unsaturated fat is hydrogenated. Hydrogenation is performed in order to increase shelf-life of food Found primarily in margarines, shortenings, commercial frying fats, and baked goods. Trans fatty acids have been implicated in research as culprits in heart disease.  Trans Fatty Acid Unsaturated fatty acids are either in cis form or trans form, depending on the way in which the hydrogen atoms are attached to the points of unsaturation in the carbon chain. – If the hydrogen atoms are attached on the same side of the points of saturation, the arrangement is called cis. – If the hydrogen atoms are attached to the different sides of the points of saturation, the arrangement is called trans.  Phospholipids Important components of cell membranes. can serve as emulsifiers in the body, joining with both water and fat Also used in foods such as margarine, chocolate, salad dressings, and frozen desserts to keep the fats dispersed Widespread in foods Phospholipids  Phospholipids The phosphate end of the glycerol is “compatible” with the intracellular and extracellular fluid  Sterols These includes: – Bile acids – Sex hormones – Adrenal hormones – Vitamin D – Cholesterol Plant and animal foods contain sterols but only animal foods contain cholesterol. Why? Cholesterol is made in the liver, and plants do not have a liver. Sterols  Cholesterol Part of the cell membrane Cholesterol is a necessary component of biological membranes. Makes the membrane more fluid. Cholesterol is not essential – Liver makes cholesterol with fragments of CHO, Protein, Lipids – Body Synthesis > Dietary Cholesterol Dietary cholesterol is found only in animal-type foods Recommended Dietary Intakes for Cholesterol is 300 mg/day CHARACTERISTICS OF FAT  Characteristics of Fats In general, animal fat have higher melting points and are solid at room temperature which reflects high content of saturated fatty acids. Plants fats have lower melting points and liquid at room temperature, reflecting high content of unsaturated fatty acids. – Exception to this rule are the seed oils (e.g. coconut oil and palm kernel oil) which are high in saturated fat. Trans fatty acids physical properties generally resembles saturated fatty acids.  Characteristics of Fats The more unsaturated fat, the more liquid it is at room temperature. The more polyunsaturated the fat is the sooner it melts. DIGESTION, ABSORPTION AND TRANSPORT OF FAT  Lipoproteins The four main types of lipoproteins are: – Chylomicron: carries dietary fat from small intestine to body cells – VLDL (very-low-density lipoprotein): carries triglycerides packaged or made by the liver to various tissues in the body. – LDL (low-density lipoprotein): carries cholesterol (much of it synthesized in the liver) to body cells. A high blood cholesterol level usually reflects high LDL. – HDL (high-density lipoprotein); carries cholesterol in the blood back to the liver for recycling or disposal. Absorption of fats  Absorption of Fats Most of the newly digested fats are absorbed into lymp as part of a special package – the chylomicron. A chylomicron contains an interior of triglycerides and cholesterol surrounded by phospholipids. Protein cover the structure. Such an arrangement of hydrophobic (water-fearing) molecules (fatty acids) on the inside and hydrophillic (water-loving) molecules (proteins on the outside allows lipids to travel through the watery fluids of the body. Chylomicron  Transport of Fats Lymph: the body fluid that transports the products of fat digestion toward the heart and eventually drains back into the bloodstream – lymph consists of the same components as blood with the exception of red blood cells. Lipoproteins: clusters of lipids associated with protein that serve as transport vehicles for lipids in blood and lymph. Transport of fats FUNCTIONS OF FAT  Functions of Lipids Energy source - Provide calories (9 calories per gram) Satiety & palatability Carry fat-soluble vitamins and essential fatty acids Organ padding Insulation Hormone synthesis In foods - Contribute aroma and flavor  Functions of Fat: as Energy Source Glycogen – minor energy storage form – Bulky, contain a lot of water – Less energy per gram (4 kcal/gram) – Does not exist for longer than a few hours before being broken down and used Fat – major energy storage form – Pack tightly without water – More energy per gram (9 kcal/gram) – Can be stored and called upon for energy at any time  Functions of Essential Fatty Acid Eicosanoids regulate functions such as – Muscle relaxation and contraction – Blood vessel dilation and constriction – Blood clot formation – Blood lipids – Response to injury and infection Fever Inflammation Pain FOOD SOURCES OF FAT  Food Sources of Fats Dietary fats can be divided into two categories: visible and invisible fats. – Visible fats come from cooking oils that are plant- based (vegetable oils) and table spreads, which may be either plant-based (margarines) or animal fats (butter). – Invisible fats are natural constituents of edible biological material ranging from cereals, vegetables, fruits, pulses, nuts and oilseeds, dairy products, meat, eggs or seafood (Gunstone et al. 2007).  Food Sources of Fats Palm oil represents the main cooking oil for most Malaysians, as this country is a primary producer of palm oil. Current consumption is 6.6kg per capita/year or 17.8g/capita/day (FAO 2011). Palm oil or palm olein has an almost equal amount of saturated and unsaturated fatty acids as indicated by 40% of palmitic acid (C16:0), 4% of stearic acid (C18:0) and 43% of oleic acid (C18:1).  Food Sources of Fats Coconut oil is one of the major sources of SFA in the Malaysian diet as santan is commonly used in preparing meals. For instance, nasi lemak, curry and cendol are traditionally consumed foods that use santan. Santan contains 92% of SFA with the major fatty acids are lauric acid and myristic acid. Appendix 3.1: The fatty acid composition of various dietary fats and oils Appendices 3.2a and 3.2b: Malaysian foods with significant fat content Appendix 3.3: local fish with varying fat contents Fatty acids composition in fats and oils Fatty acids composition in fats and oils  Fat contents in Malaysian foods The types of fish rich in EPA and DHA commonly consumed by Malaysians are Indian mackerel (kembung), anchovies (bilis), yellow-tail and yellow-stripe tuna (tongkol), sardines (sardin), torpedo scads (cencaru), Indian and short-fin scads (selayang), pomfret (bawal), red snapper (merah), King mackerel (tenggiri), Fat contents in Malaysian foods Fat contents in Malaysian foods Essential Fatty Acid Food Sources of Trans Fats Food Sources of Trans Fats Fat Can Be Healthy High Fat – Low Fat High Fat – Low Fat How much fat to consume? Cholesterol Content in Foods DEFICIENCY AND EXCESS OF FAT ON HEALTH  Deficiencies of fats Fat deficiency is rare BUT can occur in individuals with malabsorption related to inhibition of bile salts necessary for fat digestion such as liver disease (Note: Deficiency of the fat-soluble vitamins (A, D, E and K) would also be adversely Fat deficiency may also occur in malnutrition related to chronic disease conditions where blood levels of EFAs, mainly LA and ALA, may be below normal as in chronic kidney disease patients  Deficiencies of fats Deficiency leads to: – Growth retardation – Skin lesions – Reproductive failure – Liver disorders – Many others  Excess intake of fats Fat deficiency has never been an issue in the Malaysian population. Instead, with the abundance of cooking oil available for local consumption, the concern is toward excess intake. Affordability and increased access to high-fat foods predisposes the population to increased consumption of energy-dense foods which coupled together with the sedentary living would create a risk for obesity.  Excess intake of fats According to the National Health and Morbidity Survey of 2015, obese Malaysians make up 17.7% of the population while those who are categorised as overweight make up 30%. Despite the overwhelming tendency to associate obesity with the percentage of fat intake, many long- term epidemiological studies fail to provide causal relationships between the two. Fat alone cannot explain obesity as higher carbohydrate intakes also contribute to the high calorie diets  Effects Fats on Blood Lipid Levels Saturated Fat – Increases total cholesterol – Increases LDL-cholesterol Polyunsaturated Fat – total cholesterol ? – LDL-cholesterol ? – HDL-cholesterol ? – Triglycerides? Monounsaturated Fat – total cholesterol ? – LDL-cholesterol ? – HDL-cholesterol ? – Triglycerides?  Effects Fats on Blood Lipid Levels Trans Fat – Increases total cholesterol – Increases LDL-cholesterol – Decreases HDL-cholesterol  Lipids and Health Oxidized LDL-cholesterol o-LDL : the cholesterol in LDLs that is attacked by reactive oxygen molecules inside the walls of the arteries – o-LDL is taken up by scavenger cells and deposited in plaque. Foam cells: cells from the immune system containing scavenged oxidized LDL cholesterol that are thought to initiate arterial plaque formation. Free radicals: highly toxic compounds created in the body as a result of chemical reactions that involve oxygen. – Environmental pollutants such as cigarette smoke and ozone also prompt the formation of free radicals.  Lipids and Health As LDL particles penetrate the walls of the arteries, they become oxidized-LDL and next are scavenged by the body’s white blood cells. These foam cells are then deposited into the lining of the artery wall. This process, known as atherosclerosis, causes plaque deposits to enlarge, artery walls to lose elasticity, and the passage through the artery to narrow. Lipids and Health  How much Fat to consume? Total fat intake: – Adults = 25-30% TEI (Note: for active men and women with normal BMI up to 35% TEI from fat is a safe limit) – Children and adolescents = 25-35% TEI – Infant 0-5 months = 40-60% TEI – Infant 6-11 months = 30-40% TEI Saturated Fat: < 10% TEI MUFA: 12-15% TEI Omega 6 PUFA: 3-7% TEI Omega 3 PUFA: 0.3-1.2% TEI END OF SLIDES