Student Outline Ch 5Weekof Mar 23Part1 PDF

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Spring 2020 NUTR 280 (01 & 02) - Lecture Outline for the Week of March 23 – Part 1 Chapter 5 on Lipids continued II. III.

Digestion, Absorption, and Transport of Fats (continued) Lipid Functions ● Functions in food: ● Functions in the body: o Concentrated source of → energy o “9” calories/gram of fat o Body’s chief Storage form of energy ▪ Reminder: TGs are the type of lipids stored in adipose tissue. They are packed tightly in fat cells without water. Its cell membrane can expand to accommodate more droplets of fat. ▪ Adipose tissue (“adipo” means fat or fatty) - system of fat-storing cells under the skin and around the organs of the body. o Adipose tissue around vital internal organs → provides padding; acts like “shock absorbers” o Adipose tissue underneath the skin insulates the body against extreme temperatures. o Major component of → cell membranes. o Cholesterol (a sterol) - used as raw material for the making of other compounds on a as needed basis such as certain hormones, bile acids, and vitamin D. It is a component of the myelin sheath. o Fats provide “essential” fatty acids. o Aid in the absorption of fat-soluble vitamins and some phytochemicals. o Needed for healthy → skin and hair. A. Functions of the Essential Fatty Acids [Linoleic acid (LA) (omega-6 PUFA) & Alpha-linolenic acid (ALA) (omega-3 PUFA)] ● Why “essential”? Body cannot make fatty acids with double bonds in the omega-3 &/or omega-6 position. They must be consumed in the diet. ● Essential fatty acids can be used to make other long-chain fatty acids. For example: 1. Arachidonic acid (omega-6) - made from linoleic acid. 2. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) (omega-3s): o Made from → alpha-linolenic acid o They are associated with → heart health. Why? → Decreases inflammation. lowers blood pressure (relax blood vessels somewhat), and reduces blood clotting. ● If the diet is low in linoleic acid & alpha-linolenic acid → long chain fatty acids that the body would normally make from the essential fatty acids would then become “dietary essentials” as well. ● Functions of the essential fatty acids: o Needed for the → making of phospholipids. ▪ They give cell membranes their structural and functional properties. ▪ FYI: Hence, the essential fatty acids are essential for growth, development, & fertility. Also needed for maintaining the structure of red blood cells and cells of the skin & nervous system. o DHA is important to the retina. Why? → promotes normal vision. o DHA and arachidonic acid: ▪ Needed to make the cell membranes of the cells that make up the → central nervous system. ▪ Infants & young children → important for normal brain development. 1

▪ Components of breast milk. ● Another function of essential fatty acids – Serve as raw material for the making of → eicosanoids. o Pronunciation - “ī-ˈ kō-sə -ˌ nȯ id”; regulatory molecules; made from omega-6 & omega-3 fatty acids; function somewhat like → “hormones” o Functions of eicosanoids: ▪ Help to regulate the contraction/relaxation of → muscles ▪ Help to regulate the dilation/constriction of → blood vessels ▪ Involved in the regulation of → blood clot formation, blood pressure, and blood lipid levels. ▪ Another function: Involved in the immune response (fever, inflammation, and pain) o The essential fatty acid from which it is made determines the “function” of the eicosanoid. Textbook example on “blood clotting: Arachidonic acid (omega-6) starting material → eicosanoid will increase blood clotting. EPA (omega-3) starting material → eicosanoid will decrease blood clotting. ● What is the recommended ratio of omega-6s to omega-3s? Why is this important? o 5:1 to 10:1 - “1” omega-3 for every “5” to “10” omega-6s. o Importance of the ratio: need omega-3 to make omega-3 eicosanoids (heart health) o One way to improve the “balance”: ▪ Eat plant sources of the omega-3 → alpha-linolenic acid (ALA) ▪ Example sources of ALA: soybeans, soy nuts, walnuts (English & black), flaxseeds (ground), chia seeds, flaxseed oil, canola oil and products that contain these ingredients. o A way to increase intakes of EPA & DHA (omega-3s) → fatty fish and seafood. ▪ Fatty fish examples: mackerel, salmon, bluefish, lake trout, sardines, herring, and tuna. ▪ Reminder: EPA and DHA have major heart health benefits. ▪ Examples of other seafood that contain these fatty acids, though in lesser amounts per serving compared to fatty fish: mussels, crabmeat, clams, shrimp, & lobster. Seaweed (marine algae) contains DHA. ▪ American Heart Association recommendation: ● Eat fish how often? twice a week. ● Preferred source of omega-3s? from food. ● Fish oil supplements are recommended for which population groups? Individuals with coronary heart disease and/or high TGs in the blood. ● What are some health concerns with ingesting large doses of supplemental omega-3s? excessive bleeding and increases levels of LDLs (“bad” cholesterol). ● “Children and pregnant women are advised by the U.S. Food and Drug Administration (FDA) to avoid eating those fish with the potential for the highest level of mercury contamination (such as shark, swordfish, king mackerel or tilefish), eat a variety of fish and shellfish that are lower in mercury (such as canned light tuna, salmon, pollock, catfish), & check local advisories about the safety of fish caught by family and friends in local lakes, rivers and coastal areas. ▪ Another benefit of eating fish → reduces intakes of meats and other foods that may be high in saturated fats and trans fat. ▪ Ways to limit the intake of contaminants: Limit intakes of fish that have high levels of mercury (shark, swordfish, king mackerel, & tilefish) by varying the types of fish eaten; 2

remove parts that may contain concentrated amounts of contaminants (skin, any fatty material, & the “dark” meat of the fish) and select fish that are lower in the “food chain”. (Figure 13.11 within Chapter 13 on How Safe is Our Food Supply?)

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