CH-5-6 Proteins – Nutrition for Sport and Exercise : Chapter Notes

This Document Contains Chapters 5 to 6 Chapter 5: Proteins Overarching Concepts 1. Protein is a critical nutrient for humans. 2. The body is in a constant state of protein intake, turnover, and excretion. 3. Sufficient energy intake is necessary for protein anabolism. 4. Prolonged endurance exercise results in the catabolism of some protein for energy. 5. All metabolic pathways are integrated and visceral and skeletal proteins can be broken down under adverse physiological conditions. 6. Many athletes consume safe and healthy amounts of dietary protein; some athletes are at risk due to low protein and energy intakes. 7. There are many sources of protein, including animal foods, plant foods, and protein supplements. 8. Most athletes can meet their protein needs from food alone but protein supplements are likely to be safe for healthy adults. Learning Objectives LO 5.1 Describe amino acids and how the structure of a protein affects its functions. LO 5.2 Describe the digestion, absorption, and transportation of amino acids. LO 5.3 Explain protein metabolism and the processes associated with skeletal muscle protein synthesis and breakdown. LO 5.4 Explain daily protein recommendations for athletes and the amount and timing of protein intake before, during, and after exercise. LO 5.5 Describe the effects of low protein and energy intakes on training, recovery, performance, and health. LO 5.6 Translate protein recommendations into daily food intake and assess an athlete’s dietary protein intake. LO 5.7 Evaluate dietary supplements containing amino acids and proteins for safety and effectiveness Chapter Outline I. Introduction A. Pre-test assessment B. Introductory concepts 1. Protein functions optimally when energy intake is sufficient 2. Proteins play many functional roles, including tissue growth, enzymes, hormones, and immune system response 3. Basic component of protein is the amino acid 4. The amount of protein recommended for athletes is typically higher than for nonathletes 5. Protein supplements are no more or less effective than food proteins 6. Consumption of protein after exercise is important II. 5.1 Structure and function of protein • The basic protein unit is an amino acid. • In adults, nine amino acids are indispensable. • Complete and incomplete proteins differ due to their indispensable amino acid content. • Proteins are a critical element in many body functions including being a part of enzymes and skeletal muscle tissue. A. Amino acids form the basic structure of proteins. 1. 16% nitrogen 2. 20 different amino acids, each with a different structure B. Some amino acids cannot be manufactured by the body and must be provided by food. 1. Indispensable amino acids a. Cannot be manufactured by the body b. 9 of the 20 are indispensable c. Older term is essential amino acid 2. Dispensable amino acids a. Can be manufactured in the liver b. 11 of the 20 are indispensable c. Older term is nonessential amino acid d. 6 of the 11 are conditionally indispensable 1) The body cannot manufacture enough under stressful conditions 2) Endurance exercise, starvation, illness, injury 3) In U.S., most people consume enough protein a) Exceptions include those with disordered eating or eating disorders C. Proteins vary in quality due to the amount and types of amino acids present. 1. Humans need the proper amounts and types of amino acids 2. Animal and plant proteins differ a. Animal proteins are termed complete 1) Proper amounts and types of all the indispensable amino acids b. Plant proteins are termed incomplete 1) Missing one or more of the indispensable amino acids 2) Complementary proteins a) Combining of two plant proteins to provide all the indispensable amino acids 3. Spotlight on... Protein Quality D. The structure of a protein determines its functions. 1. Definitions a. Peptide: 2 or more amino acids b. Dipeptide: 2 amino acids c. Tripeptide: 3 amino acids d. Polypeptide (protein): many amino acids 2. Structure of proteins a. Primary structure 1) Determines how a protein functions b. Secondary structure 1) Weak bonding of amino acids in close proximity 2) Rigidity or stability such as in collagen c. Tertiary structure 1) Interactions of amino acids not in close proximity 2) Positive or negative charge such as in plasma proteins d. Quaternary structure 1) Protein is made up of 2-4 polypeptides 2) Can interact with other molecules 3) Insulin and hemoglobin are examples E. Proteins perform many functions in the body. 1. Enzymes a. Catalyze (speed up) chemical reactions b. Quaternary structure allows enzymes to interact with other compounds 2. Hormones a. Chemical messengers b. Insulin, glucagon, human growth hormone are examples c. Secondary and quaternary structures are important for proper function 3. Structural proteins a. Provide rigidity and durability b. Actin, myosin, collagen are examples c. Secondary and quaternary structures are important for proper function 4. Transport proteins a. Transportation of compounds in the blood, plasma, or lymph b. Lipoproteins and hemoglobin are examples c. Quaternary structure allows interactions with other compounds 5. Immune system a. Protects the body from invasion of foreign particles b. Antibodies are polypeptide chains 6. Spotlight on... Amino Acids as Regulators Questions for discussion: (1) How do structural differences of proteins influence function? (2) How do plant and animal proteins differ in quality? III. 5.2 Digestion, absorption, and transportation of protein • The proteins found in food are eventually broken down into one, two, or three amino acid units for absorption. • Indispensable amino acids are absorbed more rapidly than dispensable amino acids. • Once absorbed, the liver monitors the supply and delivery of amino acids. • The amino acid pool contains amino acids recently absorbed from food as well as amino acids from the breakdown of skeletal muscle tissue. A. Proteins are digested in the mouth, stomach, and small intestine. 1. Denatured in the stomach 2. HCl activates pepsin 3. Broken down further in the intestine by other digestive enzymes B. Proteins are absorbed in the middle and lower part of the small intestine. 1. Primarily in the jejunum and ileum 2. 2/3 in the form of di- or tri-peptides; 1/3 as amino acids 3. Indispensable amino acids absorbed more quickly than dispensable 4. “Predigested” protein supplements 5. Exogenous vs. endogenous sources C. After absorption, some amino acids are transported to the liver whereas others circulate in the blood. 1. Liver is the clearinghouse for most amino acids 2. Branched chain amino acids (BCAA) circulate immediately in the plasma 3. Blood amino acid concentration is increased for several hours after a protein-containing meal 4. Amino acid pool a. Free amino acids circulating in blood or fluid near cells b. Average of 150 g of amino acids; approximately 80 g is glutamine c. More dispensable than indispensable amino acids d. Always in flux because of protein turnover Question for discussion: What happens to a protein from the time that you eat it until the time that the amino acids are absorbed by skeletal muscle cells? IV. 5.3 Metabolism of proteins and amino acids • The body is in a constant state of protein turnover. • Skeletal muscle proteins are synthesized using amino acids from the amino acid pool, a process known as anabolism. • Conversely, skeletal muscle can be broken down to provide amino acids back to the pool, a process known as catabolism. • Some proteins are broken down and the nitrogen is excreted, one reason that some protein must be eaten daily. • Athletes who want to build skeletal muscle tissue must be in positive nitrogen balance and positive net protein balance. • Restricting energy intake (“dieting”) favors breakdown of skeletal muscle mass. • Proteins are synthesized through the process of gene expression, in which a specific area of a cell’s DNA is stimulated to direct organelles to assemble amino acids into specific protein structures. • Exercise, particularly strength training, stimulates muscle cells to increase protein synthesis. • Adequate dietary intake of protein is necessary for the proper functioning of the immune system. A. Protein anabolism and catabolism 1. Liver plays a major role 2. Deamination is removal of an amino group a. Alpha-keto acid is formed b. “Carbon skeleton” is oxidized for energy; nitrogen is excreted 3. Transamination is the transfer of an amino group a. Process used to form dispensable amino acids in liver 4. Amino acids not used by liver at time of absorption become part of amino acid pool B. The body uses amino acids to build proteins, a process known as anabolism. 1. Liver will manufacture enzymes and proteins 2. Liver is also involved in manufacture of nitrogen-containing compounds C. The body breaks down proteins into amino acids, a process known as catabolism. 1. Amino acids are not “stored” for future use 2. Amino acids can be used for energy a. 4 kcal/g b. Not the preferred source of energy for exercise c. Protein-sparing effect d. Amino acids have different entry points into the Krebs Cycle e. Six amino acids are commonly used by muscle 1. Leucine, isoleucine, and valine (branched chain amino acids) 2. Aspartate, asparagine, and glutamate 3. Protein breakdown stimulated by cortisol f. The stress of prolonged endurance exercise 1. As muscle glycogen declines, leucine oxidation increases 2. Amino acids rarely provide more than 10% of total energy g. Amino acid catabolism produces ammonia 1. Ammonia must be converted to urea and excreted in urine 2. Some nitrogen is lost every day in urine h. Amino acids and gluconeogenesis 1. 18 of the 20 amino acids could be used to produce glucose 2. Alanine produced in the muscle is a prime example 3. Effects of training on protein usage a. Endurance training seems to enhance fat oxidation so amino acids are spared D. The body is constantly breaking down proteins as well as building proteins. 1. Body is in constant state of protein turnover 2. 1-2% of body protein is degraded daily 3. Body proteins turn over at different rates 4. Nitrogen balance a. Difference between nitrogen intake and loss over several weeks b. Nitrogen balance: Intake = loss 1) Most adults are in nitrogen balance c. Positive nitrogen balance: Intake > loss 1) Needed for growth 2) Children and adolescents 3) Adult growth states (e.g., pregnancy, increases in skeletal muscle) d. Negative nitrogen balance: Loss > intake 1) Undesirable 2) Starvation (voluntary and involuntary) 5. Labile protein reserves a. Mechanism to respond to short-term reduction in protein intake b. Amino acids provided by visceral proteins 6. Influence of starvation a. Labile protein reserves protected b. Skeletal muscle proteins sacrificed c. Hormonal milieu favors muscle protein breakdown E. Skeletal muscle protein synthesis is complicated and is influenced by many factors. 1. Skeletal muscle anabolism a. Stimulation of genes that synthesize specific proteins b. Example: Mechanical stress of force production in muscle stimulates genes that regulate muscle protein synthesis c. Transcription d. Translation e. Analogy: Building a house 2. Factors that influence skeletal muscle anabolism a. Genetics b. Resistance exercise c. Nutrition (e.g., protein and energy intakes) d. Hormones (e.g., insulin) 3. Maximum versus optimum skeletal muscle protein synthesis a. The optimal muscle mass varies by sport, and isn’t necessarily the maximum attainable b. Spotlight on... Maximizing Skeletal Muscle Mass 1) Large amounts of protein daily – recommended max = 2.5 g/kg/d 2) 30-50 g of protein per feeding 3) Consumption of leucine before bed and during the sleep cycle F. Adequate protein is necessary for the optimal function of the immune system. 1. Impact of injury or infection on protein status 2. Effects of exercise on the immune system Questions for discussion: (1) Why is the amino acid pool important? (2) Under what conditions are nitrogen and protein balance positive or negative? (3) How would you describe to a novice strength athlete the various factors that influence skeletal muscle protein synthesis? (4) Why is it important for someone who is injured or sick to consume an adequate amount of protein? V. 5.4 Protein recommendations for athletes • It is recommended that athletes consume 1.0 to 2.0 grams of protein/kg body weight/day, depending upon level and type of activity. • The amount of protein intake should be determined on a gram per kilogram of body weight basis. • Vegetarian and vegan athletes need to include high-quality protein in their diets and may want to increase protein intake approximately 10 percent over the general recommendation for athletes to account for the lower digestibility of plant proteins. • Protein intake within 2–3 hours after resistance exercise is an important strategy for supporting skeletal muscle protein synthesis. • Consumption of protein after endurance exercise may help slow down or reverse the process of muscle degradation and may help recovery, particularly when combined with carbohydrates. • The consumption of proteins before or during endurance exercise has not been shown to improve performance over the consumption of carbohydrate alone. • Short-term protein intake in excess of the recommended amount for athletes (>2.0 g/kg/day) does not appear to be detrimental, but is not associated with increased synthesis of muscle mass. A. Recommended ranges for protein intake by athletes are good guidelines but should be individualized for each athlete. 1. See Table 5.3 a. DRI is 0.8 g/kg/day b. General guideline for athletes: 1.0-2.0 g/kg/day c. Guideline for recreational athletes: 1.0 g/kg/day d. Guideline for strength athletes: 1.2-1.7 g/kg/day or 1.5-2.0 g/kg/day e. Guideline for endurance athletes: 1.2-1.4 g/kg/day f. Guideline for ultrendurance athletes: 1.2-2.0 g/kg/day g. Focus on research: Establishing Dietary Protein Recommendations for Endurance and Strength Athletes 2. Spotlight on... Protein Intake Expressed as a Percentage of Total Calories Can Be Deceiving a. Relative amounts can be inaccurate if energy intake is inadequate b. 10% of total energy intake is typically equal to 0.8 g/kg/day c. General guideline if energy intake is adequate: 1) 10-15% for endurance athletes 2) 15-20% for strength athletes d. g/kg basis is preferred (absolute amount) 3. Recommended protein intake for vegetarian athletes a. General recommendation + 10% b. Takes into account lower digestibility of plant proteins c. Energy intake should be sufficient d. Emphasize protein-rich vegetarian sources B. Timing of protein intake is important, especially after exercise. 1. Protein consumption after resistance exercise a. Take advantage of “anabolic window” b. Amino acid intake immediately after exercise is beneficial 1) 10-20 g 2) Consume a food or beverage with animal protein 2. Carbohydrate-protein consumption after exercise a. Carbohydrate (CHO) intake provides energy and restores glycogen b. High-glycemic CHO stimulates insulin secretion c. Insulin stimulates amino acid uptake into muscle 3. Carbohydrate-protein consumption during exercise a. CHO-to-protein ratio of 3:1 or 4:1 4. Protein consumption before exercise – insufficient evidence of benefit C. Most athletes consume a sufficient amount of protein, but some consume a low or excessive amount. 1. Most athletes consume sufficient protein 2. Low protein intake is more common in weight-restricted sports D. There are some problems associated with consuming an excessive amount of protein. 1. Short-term effects a. Short-term, high protein intake seems to be safe in healthy adults b. Adequate fluid intake needed to prevent dehydration c. Consider protein intake in relation to need for CHO and fat 2. Long-term effects a. Increased calcium excretion b. Impact on renal disease? Questions for discussion: (1) Why do endurance athletes have a need for protein that is higher than the DRI for adults? (2) What is the rationale for including protein (amino acids) in a sports drink intended to be consumed during exercise? (3) How is it possible for an athlete to consume 25 percent of his or her diet as protein, yet be deficient in protein intake? VI. 5.5 Effect of energy intake on protein intake • Most athletes consume a sufficient amount of protein daily. • High-protein diets are not associated with kidney dysfunction or excessive loss of calcium. • Low-protein, low-calorie diets can negatively affect performance and health. • Athletes who restrict calories should consume sufficient protein (approximately 1.5 g/kg/d) to help preserve skeletal muscle mass. A. Long-term, substantial energy deficits typically result in low protein intake. 1. More protein is needed daily 2. Protein intake may be low to marginal in some athletes with disordered eating or eating disorders B. Long-term, small energy deficits are characteristic of a pattern of eating for some athletes. 1. Pattern of eating may be small, daily energy deficits 2. Increasing daily protein intake is prudent C. Intermediate-term, small-to-medium energy deficits (“dieting”) may lead to loss of lean body mass. 1. Evidence is lacking that high-protein, energy-deficient diets are more effective for fat loss and maintenance of skeletal muscle 2. Such diets are often recommended and seem to be prudent D. Short-term, substantial energy deficits are used to “make weight,” but such diets can have detrimental effects. 1. Loss of water and protein may be substantial E. There are some problems associated with low protein and calorie intake. 1. Inability to build or maintain skeletal muscle a. Body cannot maintain protein balance b. Skeletal muscle mass and functionality are reduced 2. Inability to support a fully functioning immune system – Immune system is negatively affected Question for discussion: If you looked across the weight room at the athletes’ training center on a university campus, which athletes might be at risk for low caloric and protein intakes and which might be at risk for excessive protein intakes? VII. Translating protein intake recommendations to practical, daily food choices • Protein is found in both plant and animal foods. Protein supplements are neither superior nor inferior to food proteins. • Vegetarian and vegan athletes can meet their protein needs if their diets are well planned and contain a variety and sufficient amount of plant proteins. A. There are animal and plant sources of protein. 1. Many protein-containing foods to choose from 2. Some may also contribute CHO and/or fat B. Spotlight on a real athlete 1. Lucas, a Cross Country Runner 2. Marcus, a Running Back (American Football) C. Vegetarians and vegans restrict their intake of certain protein foods. 1. Complementary proteins a. Examples: beans and rice, lentils and rice 2. Soy protein isolate is a very high-quality plant protein D. Protein supplements should be considered a part of an athlete’s overall protein intake. 1. Protein supplementation a. Not required because enough protein can be obtained from food b. Convenient c. Neither more nor less effective than food proteins d. Seems to be safe in healthy adults 2. Protein supplement ingredients a. Whey versus casein – Both are milk proteins b. Whey is liquid portion when milk is coagulated c. Whey protein isolate is concentrated source of protein 1. Lactose free 2. High in indispensable amino acids, particularly BCAA 3. Amino acids are absorbed more rapidly than from casein—“fast-acting” 4. Often consumed immediately after exercise 5. Effectiveness has been mixed in research studies to date 3. Effect of protein source on skeletal muscle growth 4. Spotlight on supplements: National Collegiate Athletic Association (NCAA) Bylaws and Nutritional Supplements – NCAA institutions cannot provide muscle-building supplements to athletes Question for discussion: How can vegetarians or vegans ensure that they are consuming all of the indispensable amino acids in their diet? VIII. Supplementation with individual amino acids • Although individual amino acid supplements seem safe, they generally are not effective for improving performance, body composition, or health. A. Essential amino acids (EAA) 1. Supplement source of indispensable amino acids 2. Lack of studies showing effectiveness B. Beta-alanine may help to buffer muscle pH in high-intensity (sprint) exercise. C. β-hydroxy-β-methyl butyrate (HMB) does not appear to be effective for increasing skeletal muscle strength or reducing skeletal muscle damage after resistance exercise. 1. Metabolite of leucine 2. In untrained athletes, studies have generally shown effectiveness for increasing muscle size and strength 3. In trained athletes, studies have generally shown no effectiveness for increasing muscle size or strength D. Branched chain amino acids (BCAA) may help to support immune function in endurance athletes. 1. Leucine, isoleucine and valine 2. 5-20 g of supplemental BCAA seems to be safe 3. Effectiveness has been mixed in research studies to date 4. Some promise for decreasing mental fatigue and improving immune responses E. Glucosamine/chondroitin sulfate is generally not effective for reducing joint pain. 1. Supplement sold to relieve join pain in athletes and osteoarthritis 2. Often sold in combination with chondroitin 3. Glucosamine is produced by body; not related to dietary intake 4. Known as a “joint lubricant” 5. Proposed mechanisms a. May prevent breakdown of cartilage b. May stimulate cartilage synthesis c. May delay progression of osteoarthritis 6. 1,500 mg of glucosamine/1,200 mg of chondroitin seems to be safe 7. Some individuals may be non-responders 8. Large 2006 study suggests no benefit over placebo for reducing knee pain by 20% 9. More research needed F. Glutamine supplementation does not appear to be effective as a way to enhance the functioning of the immune system. 1. Conditionally indispensable amino acid 2. Endurance exercise is a physiological stress 3. Glutamine is a fuel source for immune system cells 4. Might glutamine supplements help reduce risk for infection? 5. Effectiveness has been mixed in research studies to date 6. 5-10 g of supplemental glutamine seems to be safe 7. Prudent approach may be an increase in daily dietary protein G. Growth hormone releasers, particularly arginine, may be effective for stimulating the release of growth hormone. H. The effectiveness of nitric oxide (NO)/arginine alpha-ketoglutarate (AAKG) is not known due to a lack of studies. Question for discussion: What factors must a collegiate or professional athlete consider when deciding whether or not to consume a “muscle-building” supplement? IX. Summary and review A. Chapter summary B. Post-test assessment C. Review questions D. References Supplementary Teaching Materials and Classroom Activities Note: The text chapter includes an application exercise featuring a cyclist training for a multi-day stage race (p. 178). Activity 5-1 Have each student determine an appropriate amount of protein for the athletes listed below. Assume that energy intake is adequate. If general recommendations are given as a range, students should briefly explain why they chose the recommendation that they did. Calculations are needed to translate the g/kg recommendation to total g of protein, using a body weight that is characteristic of the sport. Protein recommended (daily) Protein needed (daily) Sedentary adult Recreational athlete playing volleyball three times per week Bodybuilder who is training to increase skeletal muscle mass 10 km runner maintaining body composition Ironman® distance triathlete in a high-volume training period Sample answers: Protein recommended (daily) Protein needed (daily)* Sedentary adult 0.8 g/kg 55 g Recreational athlete playing volleyball three times per week 0.8 to 1.0 g/kg If training volume is low and games are non-competitive then needs probably do not exceed 0.8 g/kg. 55 g to 69 g Bodybuilder who is training to increase skeletal muscle mass 1.2 to 1.7 g/kg Student may suggest that more is needed to reflect general practice of athletes in the sport. ≈ 118 g to 167 g 10 km runner maintaining body composition 1.2 to 1.4 g/kg The figure may be on the lower end if current CHO intake is high. Alternatively, higher figure may reflect a preference for a higher-protein, lower- (but still adequate) CHO diet. ≈ 61 g to 71 g Ironman®-distance triathlete in a high-volume training period 1.2 to 2.0 g/kg Due to the high volume of training a figure closer to the higher end of the range could be appropriate. ≈ 91 g to 152 g * Sample calculations based on realistic body weights Sedentary adult: 0.8 g/kg × 69 kg = approximately 55 g Recreational volleyball player: 0.8 g/kg × 69 kg = ≈55 g; 1.0 g/kg × 69 kg = 69 g Bodybuilder (male): 1.2 g/kg × 98 kg = ≈118 g; 1.7 g/kg × 98 kg = ≈167 g 10 km runner (female): 1.2 g/kg × 51 kg = ≈61g; 1.4 g/kg × 51 kg = ≈71 g Triathlete (male): 1.2 g/kg × 76 kg = ≈91 g; 2.0 g/kg × 76 kg = 152 g Activity 5-2 Based on the athlete’s particular sport, have students identify the training cycles in which the athlete would want to increase fat-free mass. Given that information, have students estimate the amount of protein needed during each mesocycle—preparation, competition, and transition (see Chapter 1, Activity 1-2). Once protein goals are established, students can calculate recommended daily protein intake based on a realistic weight for a male or female athlete in that sport. Activity 5-3 Continue to have students evaluate their own 24-hour dietary intake over a period of 1 to 3 days (see Chapter 4, Activity 4-3), this time for protein. There are numerous in-class activities available if students have completed the dietary analysis and bring it to class. Some suggested activities include having students: 1. Identify foods consumed that are primarily protein. 2. Identify foods consumed that are high in protein and high or low in fat. 3. Distinguish foods consumed based on source (e.g., animal or plant proteins). Identify any dishes that contained complementary proteins. 4. Survey the class to see if there is anyone who consumed sufficient kilocalories but did not meet the minimum recommended protein intake (unlikely that there will be anyone). Thorough evaluation of the dietary analysis to determine if protein needs were met or well matched to the training cycle requires more time and is generally completed outside of class. If students have completed Activity 5-2 then they can determine if daily protein goals were met and if protein intake after exercise was appropriate. Activity 5-4 Have students evaluate websites associated with protein supplementation. This can be an in-class demonstration with websites pre-selected by the instructor or an out-of-class assignment. Student Assignment The purpose of the assignment is to evaluate the content material of a website selling protein supplements to athletes. Using a search engine, enter the words “protein supplements” into the search box. Choose one commercial site (.com) that sells protein supplements to athletes. Answer the following questions about the website. 1. What is the URL of the website? 2. Describe the product being sold. Who is the target audience? How is the product supposed to work? 3. Describe the objective information found on the site (e.g., ingredients, dose, physiological or biochemical roles, scientific evidence). 4. Describe the subjective information (e.g., advertising, testimonials). 5. Evaluate the objective information (e.g., comparing factual information on the site to information found in the textbook). 6. Describe the subjective information that you think would influence someone to purchase protein supplements from this website. In your opinion, what is most influential? 7. What information would you like to have seen on the website? 8. Was the following statement clearly visible on the website: “This product is not intended to diagnose, treat, cure or prevent any disease. These statements have not been evaluated by the Food and Drug Administration.” 9. Is the product being sold legal, ethical, safe, and effective? If not, why not? 10. Write a one-paragraph summary of this website. Crossword Puzzle Answer Key 1. A: vegan; D: visceral tissue 2. A: denature; D: deamination 3. proteolysis 4. alpha-keto acid 5. hypertrophy 6. transamination 7. cortisol 8. plasma 9. myofibrillar 10. labile Word Find Puzzle Answer Key • 7 functions of body proteins: enzymes, hormones, structure, transport, immunity, acid-base balance, fluid balance • 2 components of gastric juice that help digest proteins: hydrochloric acid, pepsin • 2 key processes in amino acid metabolism in the liver: deamination, transamination • 2 steps in protein synthesis: transcription, translation • 5 good protein sources for vegans: beans, legumes, nuts, soy milk, tofu • 2 milk proteins often used in supplements: whey, casein • 3 branched-chain amino acids: leucine, isoleucine, valine W T E S E M U G E L D I M M U N I T Y O R R C N N T N E E D N O E N D U R C I A A A T I U O N H O R M O N E S A W S N E S N D O T S O Y M I L K N T N N O S E E E S D N S O T T H O U L G S H L C T I T R A N S L A T I O N E C P O E R N N T R O M L N N O D A R U K O S U I A S R F L U I D B A L A N C E R E C P C A E S M M I N N T H E C I L T R I T A S B M A S R O A O M N T N E E U N I E A C E Y H E R L T I E A E N V T E O E Y D T A Z H O S S I E K I D S C A N E L O N E N N W P H E O L T O F U N H A C I D B A S E B A L A N C E W R W E W E R E Y O P U N G V A N D W E T H Y D R O C H L O R I C A C I D N T S Chapter 5 Crossword Puzzle Across Down 1. One who does not eat food of animal origin. 2. To change the chemical structure of a protein by chemical or mechanical means. 4. The chemical compound that is a result of the deamination of amino acids. 6. The transfer of an amino group. 9. The strand like _____ proteins make up the force-producing elements of skeletal muscle. 10. Proteins in the liver and other organs that can be broken down quickly to provide amino acids serve as a _____ protein reserve. 1. Tissue of the major organs, such as the liver. 2. The removal of an amino group. 3. The breakdown of proteins into amino acids. 5. An increase in the size of a muscle due to an increase in the size of individual muscle cells. 7. A glucocorticoid hormone that is secreted by the adrenal cortex that stimulates protein and fat breakdown and counters the effects of insulin. 8. A _____ protein is a polypeptide that circulates in the fluid portion of the blood or lymph. Chapter 5 Word Find Puzzle W T E S E M U G E L D I M M U N I T Y O R R C N N T N E E D N O E N D U R C I A A A T I U O N H O R M O N E S A W S N E S N D O T S O Y M I L K N T N N O S E E E S D N S O T T H O U L G S H L C T I T R A N S L A T I O N E C P O E R N N T R O M L N N O D A R U K O S U I A S R F L U I D B A L A N C E R E C P C A E S M M I N N T H E C I L T R I T A S B M A S R O A O M N T N E E U N I E A C E Y H E R L T I E A E N V T E O E Y D T A Z H O S S I E K I D S C A N E L O N E N N W P H E O L T O F U N H A C I D B A S E B A L A N C E W R W E W E R E Y O P U N G V A N D W E T H Y D R O C H L O R I C A C I D N T S Instructions: In the grid above, find the following words or phrases, and then write them beside each clue. • 7 functions of body proteins: • 2 components of gastric juice that help digest proteins: • 2 key processes in amino acid metabolism in the liver: • 2 steps in protein synthesis: • 5 good protein sources for vegans: • 2 milk proteins often used in supplements: • 3 branched-chain amino acids: Chapter 6: Fats Overarching Concepts 1. Precise terminology is important to prevent confusion when discussing fat-related issues. 2. Fats must be considered in several contexts, including the effect they may have on performance and health. 3. Fats are an important source of energy at rest and during low-intensity exercise. 4. Fat absorption, digestion, transportation, and metabolism are slow and complicated when compared to carbohydrate. 5. For athletes in training, the need to balance carbohydrate, protein, and fat intakes results in a diet that is typically lower in fat than that of the general population. 6. Fats contain more kilocalories per gram than carbohydrates, protein, and alcohol and are easily stored in adipose tissue as a future energy source. 7. Fats in foods contribute to their good taste and it is easy to consume excess fats and kilocalories. Learning Objectives LO 6.1 Classify fats according to their chemical composition and distinguish between saturated and unsaturated, monounsaturated and polyunsaturated, cisand trans, and omega-3, -6, and -9 fatty acids. LO 6.2 Describe the digestion, absorption, and transportation of fat. LO 6.3 Explain the metabolism of fat, including mobilization, transportation, uptake, activation, translocation, and oxidation as well as ketosis and the effect it may have on training. LO 6.4 Describe how the body uses fat to fuel exercise. LO 6.5 State fat recommendations for athletes and calculate the amount of fat needed daily. LO 6.6 Identify sources of dietary fat and assess an athlete’s dietary fat intake. LO 6.7 Evaluate dietary supplements related to fat metabolism. Chapter Outline I. Introduction A. Pre-test assessment B. Introductory concepts 1. The word fat has many different meanings 2. Important source of energy at rest and during low-intensity exercise 3. Most concentrated source of energy (9 kcal/g) 4. Fats are distinguished by their chemistry 5. Certain fats in food and in the blood are associated with cardiovascular disease II. 6.1 Fatty acids, sterols, and phospholipids • Differences in the fatty acids are due to their chemical composition. • A triglyceride contains three fatty acids attached to a glycerol molecule. • Triglycerides are the most abundant type of fat in both food and the body. • The type of fat consumed can increase one’s risk for heart disease, particularly the trans fatty acids found in snack-type foods. • The type of fat consumed can influence inflammation and immune processes, such as the omega-3 and -6 fatty acids. A. Fatty acids vary due to their chemical composition. 1. Chains of carbon and hydrogen 2. Chain length varies from 4 to 24 carbons (even numbers only) 3. Double bonds are a distinguishing factor a. Saturated fatty acids b. Unsaturated fatty acids (16 to 22 carbons) 1) Monounsaturated 2) Polyunsaturated 4. Double bond formation is a distinguishing factor a. Unsaturated fatty acids 1) Cis formation 2) Trans formation 3) Spotlight on... Trans Fatty Acids 5. Fatty acid series is a distinguishing factor a. Polyunsaturated fatty acids 1) Omega-3 2) Omega-6 3) Omega-9 B. Most fats in food are in the form of triglycerides. 1. 95% of all fats in food 2. Three fatty acids attached to one glycerol a. Glycerol is a sugar alcohol b. The 3 fatty acids are typically different c. Usually one type of fatty acid is predominant 1) Saturated (e.g., coconut oil, animal fats) 2) Monounsaturated (e.g., olive and canola oils) 3) Polyunsaturated (e.g., safflower and corn oils) 3. Triacylglycerol is the scientific term a. Triglyceride is typically used in consumer health information C. Two fatty acids [essential fatty acids] cannot be manufactured by the body. a. Linoleic acid – omega-6 fatty acid found in many vegetable oils (e.g., corn, soy, safflower, sunflower) b. Alpha-linolenic acid – omega-3 fatty acid found in soy, canola, and flaxseed oils, leafy green vegetables, fatty fish, and fish oils C. Omega-3 fatty acids have many beneficial effects. 1. Best known: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docasahexaenoic acid (DHA) 2. Body converts ALA to EPA and DHA in limited amounts 3. EPA and DHA have beneficial effects on blood lipids, the immune system, and inflammatory responses 4. Recommended omega-6: omega-3 ratio = 4:1 or less 5. Spotlight on... Omega-3 Fatty Acids and Athletes D. Sterols, such as cholesterol, and phospholipids are types of fat found in foods. 1. Sterols have a ring structure a. Cholesterol b. Vitamin D c. Sex hormones 2. Cholesterol a. Only found in animal foods b. Also manufactured in the body 3. Phospholipids a. Similar in structure to triglycerides b. Contain phosphate c. Component of cell membranes E. Some fats lower the risk for heart disease. 1. From a performance perspective a. Fat provides energy at rest and during low-intensity exercise 1) Released from storage in adipose tissue 2) Released from storage in muscle b. The original source from food (e.g., saturated vs. unsaturated) is not important 2. From a health perspective a. Intake of certain fats may reduce heart disease risk 1) Omega-3 fatty acids b. Intake of certain fats may increase heart disease risk 1) Saturated fatty acids 2) Dietary cholesterol (in some people) 3. Athletes must balance both perspectives Question for discussion: If cholesterol is needed for cell membranes, why is it often labeled as being “unhealthy”? III. 6.2 Digestion, absorption, and transportation of fats • The digestion and absorption of dietary fats involves several steps. • The transport of fats involves other compounds because fat and water do not mix. A. Fat is primarily digested in the small intestine 1. Small intestine a. Pancreatic lipase b. Di- and monoglycerides 2. Gastric emptying rate 3. Satiety B. After being absorbed, the fatty acids are resynthesized into triglycerides. 1. Enter mucosal cells via passive diffusion 2. Majority are re-assembled into triglycerides a. 16- or 18-carbon fatty acids b. Incorporated into chylomicrons (lipoproteins) 3. 4- to 10-carbon fatty acids pass through mucosal cells unchanged C. The transportation of fats into the blood is a slow process. 1. Triglycerides are slowly released into lymph 2. Other fatty acids are released into blood via the portal vein 3. Blood fatty acid concentration is increased for several hours 4. Cellular triglyceride absorption a. Adipose and muscle cells are important storage sites b. Lipoprotein lipase (LPL) stimulates the release of fatty acids from the triglycerides Question for discussion: Why might a high-fat meal 2 hours prior to a competition be a bad idea for an athlete? IV. 6.3 Storage and metabolism of fats • Fats are stored as triglycerides formed from a glycerol and three fatty acids. • Fat is energy dense, containing 9 kcal per gram. • In order to be used, fats must be translocated, or broken down, from their storage form and transported to the site of usage. • In order to be metabolized aerobically, fatty acids must be converted to fatty acyl-CoA, transported into the mitochondria, and converted to acetyl CoA via β-oxidation. • Fats are more readily metabolized by tissues with a higher aerobic capacity. • Ketone bodies can be produced as a result of fat metabolism, and an overreliance on fat metabolism can result in ketosis. A. Fat can be easily stored in the body. 1. Lipoprotein lipase activity is stimulated by insulin 2. Fatty acids are re-assembled in adipose and muscle cells a. Subcutaneous and visceral fat b. Slow-twitch skeletal muscle, heart muscle 3. Advantages a. 9 kcal/g (twice that of CHO or protein) b. Anhydrous B. Fat is an important source of energy for many athletes. 1. Advantage: High yield of ATP 2. Disadvantage: Slow, complicated metabolism 3. Fat mobilization, circulation, and uptake a. Mobilization from storage 1) Hormone-sensitive lipase (HSL) 2) Stimulated by catecholamines, growth hormone, cortisol a) Released during stress b) Exercise, starvation, fasting 3. Inhibited by insulin b. Circulation and uptake 1. Glycerol goes to liver a) Converted to glucose via gluconeogenesis b) Re-assembled into triglycerides 2. Fatty acids attach to albumin for transport 3. Uptake in tissues a) Heart muscle cells b) Slow-twitch muscle fibers 4. Activation and translocation within the cell a. Use of ATP to activate b. Activation takes place in outer mitochondrial membrane c. Translocation takes place in mitochondrial matrix 1) Requires carnitine 5. Beta oxidation a. Fatty acid chain is cleaved into 2-carbon segments b. Acetyl CoA enters the Krebs Cycle c. NAD/FAD pick up electrons that are used in the electron transport chain 6. Ketosis a. Ketone bodies 1) acetoacetate 2) Beta-hydroxybutyrate 3) Acetone b. Normal metabolic pathway c. ≈2 to 6% of body’s energy needs after overnight fast d. Pathway is sometimes emphasized 1) Starvation state 2) Low CHO intake 3) Impaired CHO metabolism (diabetes) a) Dangerous, can result in ketoacidosis e. Low CHO intake/ starvation 1) Ketones are source of energy for brain 2) Muscle glycogen depleted 3) Loss of some skeletal muscle 4) Weight (fat) loss f. Not likely to be beneficial for athletic performance Questions for discussion: (1) Why does it take a number of minutes for fat metabolism to increase during aerobic exercise? (2) Why might a bodybuilder hear from other bodybuilders that ketosis is beneficial? V. 6.4 Fats as a source of energy during exercise • Fat utilization can be determined by the respiratory exchange ratio (RER), which is the ratio of carbon dioxide produced to oxygen consumed. • The percentage of energy derived from fat metabolism decreases as activity and exercise intensity increases. • As exercise intensity increases, the total amount of energy derived from fat metabolism increases, reaches a peak, and then begins to decrease. • If exercise continues at the same intensity for long periods of time (for example, hours), the relative amount of energy derived from fat metabolism increases slightly (if the athlete does not consume any carbohydrate during exercise). • Regular aerobic exercise training increases the body’s ability to metabolize fat, particularly during exercise at the same absolute exercise intensity. • Increasing the amount of fat in the diet increases reliance on fat as an energy source at rest and during lower intensities of exercise, but does not result in improved performance at higher exercise intensities. • Caffeine may increase the mobilization of fatty acids during exercise, but does not appear to improve performance due to increased fat metabolism. A. Use of fat during exercise 1. Advantages a. Abundant in food supply b. Energy dense c. Substantial storage in adipose tissue d. Produces large amount of ATP 2. Disadvantages a. Takes time to transport and metabolize b. Requires oxygen B. It is important to know the relative (percentage) and absolute amount of fat utilized as a fuel. 1. Relative vs. absolute a. Relative: % energy derived from CHO or fat b. Absolute: Total amount of energy expended 2. Fat oxidation during exercise a. At rest 1) % energy from fat is high 2) Total energy expenditure is low b. Moderate-intensity exercise (compared to rest) 1) % energy from fat decreases 2) % energy from CHO increases 3) Total energy expenditure increases substantially a) kcal from CHO increases b) kcal from fat increases c. Increasing exercise intensity (compared to moderate) 1) % energy from fat decreases 2) % energy from CHO increases 3) Total energy expenditure from fat and CHO increases 4) Maximum point of fat oxidation a) % energy from fat decreases b) Total energy expenditure from fat decreases c) Lactate production inhibits fat mobilization d) Blood circulation to adipose tissue decreases 3. Fat oxidation during prolonged steady-state exercise a. CHO stores (glycogen) decline b. % energy from CHO decreases c. % energy from fat increases gradually 4. Do you have to burn fat to lose fat? a. Low-intensity exercise (“fat-burning zone”) 1) RER is lower than during high-intensity exercise 2) % energy derived from fat is high 3) Total amount of energy expended is lower b. Not necessary to burn fat during exercise to lose body fat c. Total energy expended is more important than % expended from fat C. The body adapts to endurance exercise training by improving its ability to metabolize fat. 1. General adaptations a. Fatty acids are more easily mobilized from adipocytes b. Uptake of fatty acids into muscle cells is enhanced c. Number and size of mitochondria are increased 2. Dietary manipulations to enhance fat metabolism – High-fat diets/fat loading a. Endurance performance not likely to improve b. Intensity of exercise would be too low to be competitive c. Focus on research: Determining the Effect of High-Fat Diets on Fat Metabolism during Exercise and Endurance Exercise Performance 3. Effect of caffeine on fat usage a. Dose: 5 to 6 mg/kg body weight b. Does not increase fat mobilization c. Central nervous system stimulant 1) Increases sense of awareness 2) Decreases perceived effort d. May be banned substance 1) Normal use not likely to exceed threshold e. Caffeine is addictive and has side effects Questions for discussion: (1) Why does fat metabolism increase slightly after several hours of exercising at the same intensity? (2) Why is it erroneous to recommend a low “fat-burning” exercise intensity to help someone lose body fat? VI. 6.5 Fat recommendations for athletes • To determine the appropriate fat intake, the athlete must consider total caloric, carbohydrate, and protein intakes. • Some athletes consume too much fat relative to the amount of carbohydrate and protein needed. They need to slightly increase carbohydrate and protein intakes and reduce fat intake to a degree. • Some athletes chronically consume too little dietary fat as part of a semistarvation diet, and training, performance, and health may suffer. • If done appropriately, reducing fat intake can be an effective strategy for body fat loss. A. Total daily fat intake depends on total energy, carbohydrate, and protein intakes. 1. Total energy (kcal) need 2. Macronutrient balance a. Higher CHO/protein intake typically means lower fat intake b. Severe restriction of fat intake not recommended 3. Often expressed as a % of total energy intake a. 20 to 35% total caloric intake 4. May be expressed on g/kg body weight basis a. ≈1.0 g/kg daily b. May need to be as high as 3.0 g/kg (ultra endurance athletes) 5. Spotlight on... Must an Athlete’s Diet Be a “Low-Fat” Diet? B. Reducing caloric intake by reducing dietary fat intake over several weeks or months may help athletes achieve a loss of body fat. 1. Reducing body fat may result in improved performance 2. Fat intake is typically reduced since reductions to CHO or protein intakes may be detrimental to performance 3. Athletes may consume a short-term, low-fat diet to achieve body composition goals 4. Acute and chronic fat and energy deficits a. Acute 1) “Making weight” b. Chronic 1) Maintaining a low % body fat 2) Fat phobia C. Inadequate fat intake can negatively affect training, performance, and health. 1. Inadequate replenishment of intramuscular fat stores 2. Inability to manufacture sex-related hormones 3. Decline in high-density lipoprotein cholesterol (HDL-C) 4. Inadequate fat-soluble vitamin intakes Question for discussion: What concerns might you have if an athlete told you that she considers all fatty foods “bad”? VII. 6.6 Translating daily fat recommendations to food choices • The amount and type of fat in food varies. • Athletes often choose lower fat versions of food. • Many "fat-free" products are not low in calories. A. The amount and type of fat in foods varies. 1. Predominantly monounsaturated a. Olive, canola, and peanut oils b. Some safflower oils c. Avocado d. Nuts 2. Predominantly polyunsaturated a. Corn, soy, and flaxseed oils b. Some safflower oils c. Liquid and soft (tub) margarines d. Mayonnaise and some salad dressings e. Sunflower, pumpkin, and flax seeds 3. Predominately or some saturated a. Bacon grease and lard b. Hard (stick) margarine c. Butter, cream d. Coconut oil B. The typical American diet is usually too high in fat for an athlete in training. 1. Traditional American diet tends to be high in fat 2. Traditional ethnic diets tend to be lower in fat 3. Traditional American diet tends to be too high in fat and too low in CHO for athletes C. There are ways to modify the typical American diet so it is lower in fat. 1. Reduce portion size 2. Prepare foods with less fat 3. Add less fat to foods 4. Order carefully at restaurants 5. Be aware of “hidden fats” 6. Consume lower-fat cuts of meat or poultry and low-fat or nonfat dairy products 7. Choose lower-fat versions of high-fat processed foods 8. Substitute fruits and vegetables for fat-containing snack foods D. Some foods are made with fat substitutes. 1. Fat substitutes a. Often made from CHO sources b. Such products may not have fewer kcal than original product c. Olestra (Olean®) is not absorbed d. Not a weight loss panacea E. Spotlight on a real athlete: Lucas, a Cross Country Runner Question for discussion: How can the Nutrition Facts label be used to determine if the product has "hidden" fat? VIII. 6.7 Fat-related dietary supplements • Caffeine is an effective central nervous system stimulant and can improve endurance performance and high-intensity activities lasting up to 20 minutes. • Carnitine, MCT, and omega-3 fatty acids are not effective in healthy athletes. • Research studies suggest that the use of omega-3 fatty acids in athletes with exercise-induced bronchoconstriction due to asthma is promising. A. Caffeine is a central nervous stimulant that helps to delay fatigue. 1. Carnitine a. Found in food and synthesized from lysine b. Deficiencies are rare c. Supplement dose: 2 to 4 g/day d. Supplements seem to be safe at such dosages e. Little evidence of effectiveness 2. Medium-chain triglycerides a. Not effective for improving endurance performance b. May impair performance in some cases 3. Omega-3 fatty acid supplements – do not appear to positively affect inflammation or immune responses or improve performance in trained athletes Question for discussion: What might be the downside to an endurance athlete using caffeine as a performance enhancer? VIII. Summary and review A. Chapter summary B. Post-test assessment C. Review questions D. References Supplementary Teaching Materials and Classroom Activities Note: The text chapter includes an application exercise requiring selection of the right meal and snack choices for several athletes (p. 231). Activity 6-1 There are several in-class activities involving visuals that can peak students’ interest in the topic of fat. 1. To illustrate how difficult it is for the body to transport fats, fill a glass bottle with equal parts of oil and water. The clear separation between the two can be seen. Shake the bottle to show fat droplets and watch how long it takes for the separation to occur again once the shaking has stopped. 2. Various nutrition education companies sell visuals (tubes, food models, etc.) that compare the amount of fat in commonly consumed foods (e.g., healthedco.com or enasco.com). Such visuals usually are attention grabbers in the classroom. 3. To illustrate the effect an increase in body fat may have, fat vests and fat wraps can be brought to class. A fat vest typically weighs 20 lb and wearing it for even 10 or 15 minutes demonstrates the effect of added body weight as fat. Fat wraps are usually one or five pounds and can be wrapped around the waist, hips, or thighs. Several nutrition education companies sell these and other products. 4. Put 5-10 food items out on display and have the class rank the items from high to low based on their fat content. Include some foods that contain “hidden” fat. Activity 6-2 Continue to have students evaluate their own 24-hour dietary intake over a period of 1 to 3 days (see Chapter 4, Activity 4-3), this time for fats. There are numerous in-class activities available if students have completed the dietary analysis and bring it to class. Some suggested activities include having students: 1. Identify foods consumed that are sources of fat. 2. Identify foods consumed that are high in monounsaturated, polyunsaturated, saturated, trans, omega-3, or omega-6 fats. Identify foods that are sources of dietary cholesterol. 3. Identify foods consumed that are sources of “hidden fats.” 4. Discuss strategies for reducing fat consumption such as portion size adjustments, preparing foods with less fat, adding less fat to foods, consuming lower-fat varieties, etc. List strategies that students have used successfully in the past as well as barriers to reducing fat consumption. 5. Calculate fat intake on a g/kg basis. This figure will not appear on the computer printout but can be calculated as follows: Total fat intake (g)/body weight (kg) Example: A 165 lb person consumes 130 g of fat 1. Calculate weight in kg 165 lb divided by 2.2 lb/kg = 75 kg 2. Total fat intake (g)/body weight (kg) 130 g divided by 75 kg = 1.7 g/kg 6. Determine the effect of food choices on fat intake. Have students alter their current fat intake by adding or changing food items. For students whose fat intake was too low, have them experiment with adding heart-healthy foods that will increase dietary fat such as nuts, seeds, or oils. For students whose fat intake was too high, have them alter their diet by substituting lower-fat foods. Thorough evaluation of the dietary analysis to determine if fat needs were met or well matched to the training cycle requires more time and is generally completed outside of class. If students have completed Activity 6-2 then they can determine if daily fat intake was appropriate. Activity 6-3 Have students evaluate websites associated with fat blockers. This can be an in-class demonstration with websites pre-selected by the instructor or an out-of-class assignment. Student Assignment The purpose of the assignment is to evaluate the content material of a website selling fat blockers to athletes and active people. Using a search engine, enter the words “fat blockers” into the search box. Choose one commercial site (.com) and answer the following questions about the website. 1. What is the URL of the website? 2. Describe the product being sold. Who is the target audience? How is the product supposed to work? 3. Describe the objective information found on the site (e.g., ingredients, dose, physiological or biochemical roles, scientific evidence). 4. Describe the subjective information (e.g., advertising, testimonials). 5. Evaluate the objective information (e.g., comparing factual information on the site to information found in the textbook). 6. Describe the subjective information that you think would influence someone to purchase “fat blockers” from this website. In your opinion, what is most influential? 7. What information would you like to have seen on the website? 8. Was the following statement clearly visible on the website: “This product is not intended to diagnose, treat, cure or prevent any disease. These statements have not been evaluated by the Food and Drug Administration.” 9. Is the product being sold legal, ethical, safe, and effective? If not, why not? 10. Write a one-paragraph summary of this website. Crossword Puzzle Answer Key 1. glycerol 2. carboxyl group 3. cholesterol 4. phospholipid 5. visceral fat 6. cis 7. esterification 8. saturated 9. subcutaneous fat 10. triglyceride 11. lymph 12. lipoprotein 13. trans Word Find Puzzle Answer Key • 3 examples of lipids: triglycerides, sterols, phospholipids • 6 types of unsaturated fatty acids: monounsaturated, polyunsaturated, trans, omega-three, omega-six, omega-nine • 2 essential fatty acids: linoleic, alpha-linolenic • 4 steps of fatty acid metabolism within cells: activation, translocation, beta oxidation, Krebs cycle • 5 sources of healthful types of fat: olive oil, canola oil, flaxseed oil, nuts, fatty fish • 6 low-fat cooking methods: grilling, roasting, broiling, baking, steaming, poaching H M O N O U N S A T U R A T E D O E D A T O L I O A L O N A C S O W N K N E T K R E B S C Y C L E L E F H E N I T R V U A T G N I H C A O P O O V O N A I E E N N G O L I V E O I L H E C A R G F L A X S E E D O I L B A K I N G U L S V C T E L E B R O I L I N G K E T Y L E L R O Y O M E G A S I X R G M A C O R T N U T S C N C O T K A H R O S E R B I R D I B E A C T I V A T I O N R E L O A A V F A T T Y F I S H L O U I T E S C I N E L O N I L A H P L A Y D S E E R O A S T I N G O S V A I C L E B E T A O X I D A T I O N E D N K O S Y P H O S P H O L I P I D S T G O P G N I M A E T S E E E R H T A G E M O Chapter 6 Crossword Puzzle Across Down 1. A carbon-, hydrogen-, and oxygen-containing molecule that is the backbone of all triglycerides. 6. Describes a chemical formation where groups are on the same side of the double bond between carbons. 9. Fat stored under the skin. 10. A fat composed of three fatty acids attached to a glycerol molecule. 12. A protein-based lipid (fat) transporter. 13. Describes a chemical formation in which groups are on opposite sides of the double bond between carbons. 2. Carbon with a double bond to oxygen and a single bond to oxygen/hydrogen. 3. A fat-like substance that is manufactured in the body and is found in animal foods. 4. A fat that is similar to a triglyceride but contains phosphate. 5. Fat stored around major organs. 7. The process of forming a triglyceride from a glycerol molecule and three fatty acids. 8. A _____ fat contains no double bonds between its carbons. 11. A fluid containing mostly white blood cells. Chapter 6 Word Find Puzzle H M O N O U N S A T U R A T E D O E D A T O L I O A L O N A C S O W N K N E T K R E B S C Y C L E L E F H E N I T R V U A T G N I H C A O P O O V O N A I E E N N G O L I V E O I L H E C A R G F L A X S E E D O I L B A K I N G U L S V C T E L E B R O I L I N G K E T Y L E L R O Y O M E G A S I X R G M A C O R T N U T S C N C O T K A H R O S E R B I R D I B E A C T I V A T I O N R E L O A A V F A T T Y F I S H L O U I T E S C I N E L O N I L A H P L A Y D S E E R O A S T I N G O S V A I C L E B E T A O X I D A T I O N E D N K O S Y P H O S P H O L I P I D S T G O P G N I M A E T S E E E R H T A G E M O Instructions: In the grid above, find the following words or phrases, and then write them beside each clue. • 3 examples of lipids: • 6 types of unsaturated fatty acids: • 2 essential fatty acids: • 4 steps of fatty acid metabolism within cells: • 5 sources of healthful types of fat: • 6 low-fat cooking methods: 1 Crossword and word find contributed by Elesha Feldman Instructor Manual for Nutrition for Sport and Exercise Marie Dunford, J. Andrew Doyle 9781285752495