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Chapter 2

Chapter 2. Carbohydrates, Proteins, and Fats: The Energy Macronutrients of Balanced Meals. Macronutrients. Macronutrients provide kilocalories (kcal), a measure of energy Carbohydrate (CHO) and protein (PRO) = 4 kcal/g Fat = 9 kcal/g

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Chapter 2

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  1. Chapter 2 Carbohydrates, Proteins, and Fats: The Energy Macronutrients of Balanced Meals

  2. Macronutrients Macronutrients provide kilocalories (kcal), a measure of energy Carbohydrate (CHO) and protein (PRO) = 4 kcal/g Fat = 9 kcal/g Alcohol (ETOH) = 7 kcal/g; alcohol is not considered macronutrient

  3. Macronutrients (continued) Macronutrients are organic—they all contain carbon Fats contain more carbon, thus being higher in kilocalories Being organic, all three macronutrients are digestible—they can break down into component molecules All three macronutrients contain carbon, hydrogen, and oxygen

  4. Foods Generally Contain a Combination of Macronutrients

  5. Carbohydrates Made up of glucose molecules: C6H12O6 Three basic forms: Sugar: monosaccharides and disaccharides Starch: polysaccharides Fiber: indigestible polysaccharide Two sources: Plants (from photosynthesis) Milk Chief energy source for the body cells (sugar and/or starch)

  6. Examples Sugar is noted with suffix “ose”: glucose = blood sugar; sucrose = table sugar; fructose = fruit sugar; lactose = milk sugar Glucose and fructose = monosaccharides Starch = polysaccharide; found in bread, peas, corn, pasta, and potatoes Fiber = indigestible polysaccharide found in plants; insoluble = skin and seeds and “crunchy” components; soluble = pulp and “gummy” components High-fiber foods have a relatively low glycemic index Glycemic load: a meal with a high content of CHO with sources that are high in glycemic index (quickly enter the bloodstream)

  7. Food Label Guidelines 60% kcal as CHO (300 g per 2000 kcal) Total CHO = sum of sugar, starch, and fiber Fiber goal = 25 g per 2000 kcal Net CHO = total CHO minus fiber and 1/2 sugar alcohols *RDA for CHO: 130 g

  8. Estimating CHO Content of Plant-Based Foods Assess 3 aspects of sensory experience of food: Level of sweetness Level of water Density ½ cup fruit (sweet): 15 g CHO ½ cup dry grains and dry (potato, legumes) or “sweet” vegetables (sweet corn, sweet peas): 15 g CHO 3 cups popcorn (low density): 15 g CHO ½ cup cooked or 1 cup raw low-CHO vegetables: 5 g CHO, (most low CHO vegetables sound odd to say, “sweet _____”) ½ cup flour (very dry): about 45 g CHO ½ cup sugar (very dry and very sweet): about 100 g CHO

  9. Protein Attributes and Functions Protein is unique among nutrients because it contains nitrogen Because of its nitrogen content, protein is used as a building source for new body cells Protein is found in all body cells and constituents such as the immune system, hormones, and digestive enzymes Dietary intake digested into amino acids; the liver reassembles these into protein

  10. Protein Sources Found in muscle (i.e., red and white meats and fish), eggs, nuts, legumes, milk, and milk products Limited amounts in grains and vegetables Only fats and sugars do not contain protein; fruit contains only trace amounts of protein and is generally considered to have none Essential amino acids (EAA)—eight required for adults, nine for children with need for histidine; certain quantity needed in the diet within a 24-hour period to make protein Complete protein source: a food containing all eight EAAs (animal products) High-biologic value diet: emphasizes foods with all EAAs

  11. FYI Examples of EAA and Sources Methionine—primary source is animal protein; metabolized into taurine and homocysteine; contains sulfur; excess intake linked with bone loss, some chronic diseases (cardiac, Alzheimer’s, diabetes) Phenylalanine—found in aspartame (NutraSweet); all U.S. infants are tested for phenylketonuria (PKU) at birth; caution on labels aimed at individuals with PKU Tryptophan—found in high amounts in turkey and milk; precursor to the hormone serotonin (that promotes a “good feeling” and helps induce sleep)

  12. Protein Needs Minimum of 50 g daily, with all EAAs Individualized needs based on age and other factors Infants: 2.24 g/kg body weight (BW) Children: 1.5 g/kg BW Adults: 0.8 g/kg BW Older adults 1.0 to 1.2 g/kg BW Athletes: 1.0 to 2.0 g maximum per kg BW Increased needs also based on health parameters (e.g., protein status or states of increased demand, such as with burns)

  13. Protein Deficiency Conditions Reduced albumin (<3.5 mg/dL) related to impaired body processes; (<2.8 mg/dL related to poor surgical outcomes with impaired wound healing and compromised immune system) Kwashiorkor: condition of protein deficiency Marasmus, or protein-calorie malnutrition (PCM)

  14. Estimating Protein Content of Foods 1 oz meat (equals ¼ cup volume) = 7 g PRO 1 egg (¼ cup volume) = 7 g PRO ½ cup legumes, ¼ cup nuts, ¼ cup cheese (1 oz) and 1 tbsp peanut butter are counted as alternative to 1 oz meat 1 cup milk = 8 g PRO

  15. Fat (Lipids) Constituent of body cell membranes: phospholipids Essential fatty acids needed for hormonal production (e.g., linoleic acid, an omega-6 fatty acid; alpha linolenic acid, an omega-3 fatty acid) Precursor of hormone-like compounds: eicosanoids Solid = saturated fats; liquid = unsaturated fats (monounsaturated and polyunsaturated)

  16. Degree of Saturation Can Be Determined by Texture at Cold Temperature General amounts of saturated fats, monounsaturated fats, and polyunsaturated fats can be determined by appearance when fats are chilled. Note that solids are on the bottom of avocado and olive oils.

  17. Food Label Guidelines Fat based on 30% kcal (65 g/2000 kcal) Saturated fat based on 10% kcal (20 g/2000 kcal) Trans fatty acids now listed; goal to have intake as minimal as possible Made from the addition of hydrogen to liquid oils; first commercial use of margarines and shortenings in the 1940s

  18. Food Sources of Fat Found in germ portion of grains, some fruits (e.g., coconut, avocado, olives), and in whole milk (including butter), meats (including lard), nuts and seeds, egg yolks Omega-3 fatty acids (found in cold-water fish) essential for brain development; plant forms include flax, walnuts, canola oil Monounsaturated fats are preferred source for health (olive, canola oil and peanut oil, olives and most nuts, avocado)

  19. Cholesterol A fatlike substance produced in the liver Found only in animal fat Not a kilocalorie source Necessary for normal body functioning Saturated fats can encourage excess production of cholesterol by the liver; unsaturated fats suppress the liver’s production of cholesterol; these processes are reflected in blood cholesterol levels To be discussed with review of Chapter 7

  20. Macronutrient Content of Food Exchanges (Per 1 Serving on Average)

  21. Sample Menu Breakfast 1 starch: 1 slice toast AM 1 fruit: ½ cup grapes 1 milk: 1 cup 2% milk 1 fat: 1 tsp butter 1 sugar: 1 tsp jam Lunch 2 starch: 2 slices bread PM 1 fruit: 1 orange 1 meat: 1 oz turkey 1 fat: 1 tsp mayonnaise 2 veg: 1 cup mini-carrots 1 milk: 1 cup plain yogurt 2 sugars: 2 tsp honey for yogurt Dinner 1 starch: ½ cup potato cooked in H/S 1 fruit/1 milk: 1 cup strawberries with 1 cup 2% milk 2 fats: 2 tsp canola oil 3 meats: 3 oz ham 2 veg: 1 cup steamed cabbage 1 fruit/sug: ½ cup applesauce with 1 tsp cinnamon sugar 1 milk: 1 cup 2% milk

  22. Menu Planning Using Food Exchanges Example: Goal 2000 kcal at 55% CHO, 15% PRO, 30% fat2000 kcal × 0.55 = 1100 kcal/4 = 275 g CHO2000 kcal × 0.15 = 300 kcal/4 = 75 g PRO2000 kcal × 0.30 = 600 kcal/9 = 66 g fat To develop meal plan, start with number servings of primary CHO foods (starch, fruit, milk; each serving 15 g CHO) Goal of 275 g CHO/15 = 18 total servings of starch/fruit/milk; determine how many of each and start doing the math

  23. 18 Servings Starch, Fruit, Milk

  24. Next Step: Add in Non-Starch Vegetables 2.5 cups vegetables = 25 g CHO (can substitute for 1 serving of primary CHO source (e.g., 1 starch) Revise sums of macronutrients Then determine amount of meat to meet remaining PRO needs for predetermined goal

  25. See Evolve for More on Food Exchanges Complete food exchanges can be found in Evolve Any food can be included into the Food Exchanges that have similar macronutrient content, for example: 1 oz potato chips = 15 g CHO and 10 g fat or 1 oz potato chips = 1 bread and 2 fat servings For Menu Planning:Optimally low-fat/skim milk should be used in calculations, with emphasis on lean meats and unsaturated fats

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