Unit 5 Lecture Notes: The Lipids

Transcription

1 Pierce College Putman/NUTR&101 Unit 5 Lecture Notes: The Lipids INTRODUCTION 1. Include TRIGLYCERIDES 1. % of body fats 2. Major energy storage for body A. Stored in fat cells We have a set number of fat cells When more lipid is absorbed, fat cells 3) Formed during a) have more fat cells as adults, so harder to 4) This hormone secreted when fat is absorbed during meal a) Binds in, turns off hunger centers ( Takes about minutes B. Fat stores more than twice the energy of C. Provides most of energy needed for 3. Use of triglycerides in food A. cal/gram ( cal/gram for carbs) Good for survival meals! (Can carry more calories per given weight.) B. We crave instinctively Our ancestors barely had enough calories to survive a) Fat has most calories/gram, so is preferred in survival situations b) Now: Craving + ready supply + ignorance = obesity! C. Fats can help with weight loss! 4. Structure: + 3 FATTY ACIDS 1. Saturated Fats A. Carbons all B. They pack together C. At room (or blood) temperature D. Bad for E. Elevate F. Should limit in diet (< % total calories) G. Sources: 3) Nuts: 2. Unsaturated Fats A. 1 or more between carbons, thus carbons are not saturated with Putman/Pierce College Nut& notes/ /page 1

2 B. Have an irregular structure, so don t C. Are at room (or body) temperature D. Regarding diet E. Reduce F. % of total calories should be from unsaturated fats G. Should max out on these fats (within limits) H. MONOUNSATURATED FATS (MUFA) Have one bond (hence mono ) Sources: a) b) c) d) Avocados (muy sabroso!) I. POLYUNSATURATED FATS (PUFA) Have bonds Essential a) Linoleic acid ( On omega ( acid + made from this (a) Involved as hormones in (3) Recommendation: % of total calories should be (a) This is 12 to 17 g; better to eat (4) Sources: (a) (b) (c) (d) b) Linolenic acid ( An omega ( EPA & DHA made from this (maybe) (a) Functions of EPA & DHA: Reduces inflammation of Relaxes Reduces LDL cholesterol Needed for normal system development May inhibit some cancers (3) Recommendation: % of total calories Putman/Pierce College Nut& notes/ /page 2

3 (a) Better to eat more! (4) Sources: (a) (b) (c) (d) (e) Oils Olive oil (Recommend: Consume tablespoons per day!) (5) More on EPA & DHA: (a) mg/day recommended of EPA ( g/day EPA therapeutic) (b) Sources: Two 3 oz servings of fatty, coldwater fish/week Due to mercury (and other toxins), go easy on Freerange meats Animals fed Changes triglyceride composition Eggs (some are very high in ) Fish oil supplements? Don t take fish oils!!! Toxic levels of vitamin A Benefits of fish oil supplements: J. HYDROGENATED FATTY ACIDS Problem: Unsaturated oils oxidize Solutions: a) Cap b) Refrigerate c) Hydrogenate! ( Add hydrogens to (a) Less susceptible to (b) Solid at (c) Results in the formation of. Both sat fats and trans fats Increase Decrease Increase Markedly increase disease risk (esp. trans fats) ( Sources (a) (b) Note that nearly all transfats are Putman/Pierce College Nut& notes/ /page 3

4 PHOSPHOLIPIDS 1. Structure: Make up cell 3. In diet, are an emulsifier: Can oils in a. Phosphate is hydrophilic b. Fatty acids are 4. Lecithin (a type of phospholipid) a. Found in b. Used to make c. Can be taken as supplement Inconclusive studies suggest it a) Lowers b) Raises STEROLS 1. Cholesterol a. Synthesizes Vitamin 3) Sex b. Stabilizes c. Forms Narrows, leads to a) b) d. Liver makes what is needed! e. Limit in diet! < mg/day if healthy; < mg/day if you have cardiovascular disease Note: One egg has about mg of cholesterol DIGESTION & ABSORPTION OF FATS 1. In mouth: A. Enzymes digest Important for 2. In small intestine: A. Bile triglycerides B. Pancreatic enzymes (lipases) digest triglycerides into C. & shortchain enter intestine D. helps longchain fatty acids enter intestine E. & enter blood F. Longchain fatty acids form, which enter STORED FAT FOR ENERGY 1. Supplies about % of resting energy needs 2. When energy is needed: Putman/Pierce College Nut& notes/ /page 4

5 A. & are used first We have only about hours of glycogen reserves B. Fat cells break fat into + Released into Most cells absorb both for 3) Some bodies released from fatty acids C. With in blood, either from food or liver release Nervous system & red blood cells absorb only glucose Other cells take in, & too! D. With insufficient glucose entering cells: Resulting from a) Low blood glucose from a low b) Inability to absorb glucose, as in Proteins are broken down into 3) increases fat breakdown & release a) Liver absorbs & ( turned into glucose & released (a) Only about % of fat molecule is glycerol! ( Some fatty acids used by liver & other cells for energy (3) Excess fatty acids released as bodies (a) Brain uses ketones only after + (b) results Blood ph (becomes more ) Urination & dehydration Respiratory rate DIETARY FATS & HEALTH 1. Heart disease, stroke and some cancers linked to A. B. C. LIPOPROTEINS & HEART DISEASE 1. Large, water insoluble fats move in blood as 2. Lipoprotein composition: A. Lipids 3) B. Proteins: 3. Lipoprotein classes: A. Chylomicrons < % protein Mostly triglycerides 3) Size: Putman/Pierce College Nut& notes/ /page 5

6 4) Block B. VLDLs % protein Triglycerides + cholesterol 3) Size: 4) Form 5) Easily oxidized; damage walls of arteries a) Antioxidants reduce this ( ( C. LDLs % protein Triglycerides + cholesterol 3) Size: 4) Also form D. HDLs % protein Low in triglycerides 3) Size: 4) Remove 5) Reduce risk of 6) To increase HDLs in blood: a) Don t b) Maintain c) Exercise d) Eat good fats, especially ( ( (3) FAT IN THE DIET 1. Top three fat sources in the US diet: 2. Dairy products A. Contain lots of Butter & cream are a) Replace with B. Try low fat/fat free dairy C. Buy & use Have stronger taste, so you use less 3. Beef A. Has lots of, especially prime & choice B. Eat smaller, less often C. USDA Food Guide recommends only oz/day of protein An 8oz steak is considered small! D. Buy lean, ground beef Putman/Pierce College Nut& notes/ /page 6

7 Regular hamburger (4 oz): 23% fat, cal, g fat/24g protein! Ground round (4 oz): 10% fat, cal, g fat/24 g protein! 3) Super lean (4 oz): 4% fat, cal, g fat/24 g protein (the best choice!) 4. Chicken & Poultry A. Eat without the B. Careful about buying ground turkey!!! It may be ground up with the 5. Eggs A. Good source of unsaturated fats & omega3s B. Eat sparingly due to DEFENSIVE DINING! 1. What we need to do: A. Know the sources of B. Limit ; omit C. Maximize and, especially 2. At the grocery: A. Read B. For everyday staples, choose C. Buy whole foods & add flavorings at home! For example, buy frozen veggies without D. Choose meats, if you want precooked meats Don t buy a) b) c) E. If you must have deli meats, choose They yield more flavor per ounce! F. Choose healthful oils! 3) What about cocoanut & palm oils? 3. At home: A. Use small amounts of cheeses Not large amounts of cheeses! Less B. Use fat or filled cheese products Sat fat and cholesterol replaced with C. Use olive oil instead of butter! Eat 2 tablespoons + per day! D. Use healthful cooking methods: Healthful: Not optimal: a) If you pan fry, use canola oil sparingly; never use solid fats (butter, lard) 3) Unhealthful: Putman/Pierce College Nut& notes/ /page 7

8 E. Eat less, use ground meat & mix with oatmeal & mushrooms! 4. At restaurants: A. Eat salads Use dressings (or & vinegar!) Warning! Some salads have more fat & calories than fastfood hamburgers! B. Think small (especially when you re hungry) Small burger (without mayo) & side salad are okay! C. Avoid fast food chicken, fish, etc. Trans fat city!!! D. Order broiled E. Use salsa instead of & on Mexican foods! TRY THE MEDITERRANEAN DIET! 1. Foods eaten daily? A. Whole B. C. Beans, D. E. F. Glass of 2. Foods eaten a few times/week? A. Fish & B. C. 3. Foods eaten a few times/month? A. Red Putman/Pierce College Nut& notes/ /page 8