Agenda Function of Lipids Types of Lipids Structures of fatty acids Hydrogenation Nomenclature

Functions Long-term ___ storage Support organs Insulation Fat soluble vitamins A, D, E, K

Types Physical Property Chemical Property Fatty acids Triglycerides Phospholipids Cholesteryl ester Vitamins

Fatty Acid Structure 1 Chain length (chemical property) Melting/boiling point (physical property) Solubility in water (physical property) Long chain FA – 12-22 carbons (most naturally occurring FA) Medium chain FA – 8-12 Short chain FA – shorter than 8

Fatty Acid Structure 2 Type of bonds (chem prop) State/phase at room temperature (phys prop) Glycerol “backbone” Poly-unsaturated fatty acid Saturated fatty acid Mono-unsaturated fatty acid

Fatty Acid Structure 3 Trans- vs. Cis- fatty acids State/phase at room temp Hydrogenation: adding hydrogen double bonds  single bonds cis double  trans double purpose: improve texture (liquid to solid) and shelf-life (less likely to oxidize)

Hydrogenation

Partial Hydrogenation Rarely found in nature Fats and oils that may contain a high proportion of trans-fatty acids are: Margarine Frying Fats Shortening

Nomenclature 18 carbons in length 3 cis double bonds Between 9th and 10th carbon Between 12th and 13th carbon Between 15th and 16th carbon α Naming System: cis9, cis12, cis15-18:3 ω Naming System: omega-3 Common Name: linolenic acid (α-linolenic acid)

Saturated Fatty Acids = No Double Bonds Stearic Acid 18:0 H H Oleic Acid 18:1 cis-9 Monounsaturated Fatty Acids = One Double Bond H Elaidic Acid 18:1 trans-9 H Linoleic Acid 18:2 cis-9 cis-12 Polyunsaturated Fatty Acids = More than One Double Bond Rumenic Acid 18:2 cis-9, trans-11

Agenda Optional pop quiz – carbohydrates & fat Nomenclature review Animal vs. plant lipids Essential fatty acids

Pop Quiz The body uses 1 as the main energy source. Excess ___ (same as above) is stored as 2 in the 3 and muscles. A(n) 4 , composed of 1 glycerol and 5 fatty acids, is the long-term storage form that stores almost three times as much energy. The body can convert fat into 6 for energy when it is necessary.

Nomenclature Name each of the following by its α and ω names (or draw its molecular structure) cis9-16:1 cis5, cis8, cis11, cis14-20:4

Properties of Triglycerides Can you explain the physical properties in terms of the chemical structures of the fatty acids? Animal foods contribute the majority of dietary SFAs, whereas plant-derived foods supply the majority of PUFAs. MUFAs come from both plant and animal foods. Tropical oils (coconut and palm) contain relatively high amounts of SFAs, and many oily fish have high levels of PUFAs.

Does the human body use lipids from our diet as the way they are? No, lipids are broken down into smaller units (fatty acids & glycerol) Once broken down and absorbed, then can be restructured/changed into forms the body can use

Essential Fatty Acids α-Linolenic Acid Linoleic Acid Omega 3 Omega 6 The body cannot synthesize double bonds in the ω-3 and ω-6 positions Biological membrane in nerve tissues and retina Necessary for epithelial cell function Involved in gene regulation

Elongation & Desaturation the body uses the essential fatty acids to make EPA and DHA by increasing the number of carbon atoms and the number of double bonds Docosahexaenoic acid (DHA) Eicosapentaenoic acid (EPA)

Conditionally Essential Fatty Acids Infants lack the enzymes to make DHA from linoleic and linolenic acids Conditionally essential nutrients must be supplied to the body only under special conditions, such as stress, illness, aging, etc.

Dietary Sources Linoleic acid: walnuts, seeds, oil (soybean, corn, etc) Linolenic acid: walnuts, oil (soybean, canola, flaxseed) Plentiful in fatty fish and seafood Small amounts in meat and eggs

Essential FA Deficiency Rare because we have stored adipose tissues patients receiving poor nutritional care diseases that disrupt lipid absorption/utilization Irritated and flaky skin Gastrointestinal problems Impaired immune function Wound healing slowly Slow growth in children