Lunch Science: Glycemic Effects as a Credence Quality
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This short lecture was developed, in part, for use in Economic Sciences 351, a food and agricultural marketing course at WSU. This version was used in a presentation to a local 4H group.
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Lunch Science: Glycemic Effects as a Credence Quality
- 1. The Science The Question The Experiment The Meals The Results Lunch Science: A Personal Dietary Investigation Prepared for Mountain View 4H Trent Smith Assistant Professor Washington State University School of Economic Sciences April 13, 2011 Smith Asymmetric Information 1 / 27
- 2. The Science The Question The Experiment The Meals The Results Glycemic Effects Though conventional wisdom has long held that dietary fat exacerbates chronic diseases such as obesity and heart disease, attention is increasingly being focused on refined carbohydrates. Reference: Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease by Gary Taubes, 2007 Smith Asymmetric Information 2 / 27
- 3. The Science The Question The Experiment The Meals The Results Glycemic Effects Though conventional wisdom has long held that dietary fat exacerbates chronic diseases such as obesity and heart disease, attention is increasingly being focused on refined carbohydrates. Refined carbohydrates are sugars and starches that have been processed in a way that speeds digestion. Reference: Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease by Gary Taubes, 2007 Smith Asymmetric Information 2 / 27
- 4. The Science The Question The Experiment The Meals The Results Glycemic Effects Though conventional wisdom has long held that dietary fat exacerbates chronic diseases such as obesity and heart disease, attention is increasingly being focused on refined carbohydrates. Refined carbohydrates are sugars and starches that have been processed in a way that speeds digestion. Chronic high blood sugar has deleterious effects on health. Side effects of uncontrolled diabetes (i.e., unchecked high blood sugar) can include polyuria, polydipsia, blurred vision, fatigue, weight gain, and (maybe) heart disease and cancer. Reference: Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease by Gary Taubes, 2007 Smith Asymmetric Information 2 / 27
- 5. The Science The Question The Experiment The Meals The Results Glycemic Effects Though conventional wisdom has long held that dietary fat exacerbates chronic diseases such as obesity and heart disease, attention is increasingly being focused on refined carbohydrates. Refined carbohydrates are sugars and starches that have been processed in a way that speeds digestion. Chronic high blood sugar has deleterious effects on health. Side effects of uncontrolled diabetes (i.e., unchecked high blood sugar) can include polyuria, polydipsia, blurred vision, fatigue, weight gain, and (maybe) heart disease and cancer. One common measure of carbohydrate quality is the glycemic index (GI), a standardized measure of blood sugar (glucose) response to individual foods. Reference: Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease by Gary Taubes, 2007 Smith Asymmetric Information 2 / 27
- 6. The Science The Question The Experiment The Meals The Results Blood Sugar and Insulin High-GI foods (e.g., white bread) can induce sudden spikes in blood sugar. Smith Asymmetric Information 3 / 27
- 7. The Science The Question The Experiment The Meals The Results Blood Sugar and Insulin High-GI foods (e.g., white bread) can induce sudden spikes in blood sugar. Your pancreas responds by secreting insulin into the bloodstream. Smith Asymmetric Information 3 / 27
- 8. The Science The Question The Experiment The Meals The Results Blood Sugar and Insulin High-GI foods (e.g., white bread) can induce sudden spikes in blood sugar. Your pancreas responds by secreting insulin into the bloodstream. Insulin tells your body to absorb glucose (by burning it, storing it in liver and muscles, and converting it to body fat). Smith Asymmetric Information 3 / 27
- 9. The Science The Question The Experiment The Meals The Results Blood Sugar and Insulin High-GI foods (e.g., white bread) can induce sudden spikes in blood sugar. Your pancreas responds by secreting insulin into the bloodstream. Insulin tells your body to absorb glucose (by burning it, storing it in liver and muscles, and converting it to body fat). GI is hard to measure: differs from person to person, is affected by cooking time, other foods included in meal, and even chewing speed. Nevertheless, published values for some foods are available. Smith Asymmetric Information 3 / 27
- 10. The Science The Question The Experiment The Meals The Results Blood Sugar and Insulin High-GI foods (e.g., white bread) can induce sudden spikes in blood sugar. Your pancreas responds by secreting insulin into the bloodstream. Insulin tells your body to absorb glucose (by burning it, storing it in liver and muscles, and converting it to body fat). GI is hard to measure: differs from person to person, is affected by cooking time, other foods included in meal, and even chewing speed. Nevertheless, published Reference: Ludwig, D. S. JAMA values for some foods are available. 2002;287:2414-2423. Smith Asymmetric Information 3 / 27
- 11. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 12. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . . . . is (prohibitively?) costly to the consumer References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 13. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . . . . is (prohibitively?) costly to the consumer . . . is asymmetric, in that it is more available to producers (who have full information about processing) References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 14. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . . . . is (prohibitively?) costly to the consumer . . . is asymmetric, in that it is more available to producers (who have full information about processing) . . . is unobservable even after consumption References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 15. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . . . . is (prohibitively?) costly to the consumer . . . is asymmetric, in that it is more available to producers (who have full information about processing) . . . is unobservable even after consumption . . . is something consumers are likely to care about, given effects on health. . . References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 16. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information Because high-GI foods are less costly to produce, and because information about glycemic effects. . . . . . is (prohibitively?) costly to the consumer . . . is asymmetric, in that it is more available to producers (who have full information about processing) . . . is unobservable even after consumption . . . is something consumers are likely to care about, given effects on health. . . . . . glycemic effects constitute what economists call a credence quality, or credence good. References: Darby & Karni (1973); Smith, Chouinard & Wandschneider (2011) Smith Asymmetric Information 4 / 27
- 17. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information, cont’d Market Problem: In the absence of a market intervention that makes it possible for producers to send credible signals about product quality (standards, certifications, etc.), credence qualities lead to a market breakdown (a.k.a. “Lemons Equilibrium”), in which low-quality goods (in this case, high-GI foods) dominate the market. Smith Asymmetric Information 5 / 27
- 18. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information, cont’d Market Problem: In the absence of a market intervention that makes it possible for producers to send credible signals about product quality (standards, certifications, etc.), credence qualities lead to a market breakdown (a.k.a. “Lemons Equilibrium”), in which low-quality goods (in this case, high-GI foods) dominate the market. Personal Problem: So which foods should I eat? Avoiding all processed food is costly. . . so it would be nice to know which products are better or worse. . . for me. Smith Asymmetric Information 5 / 27
- 19. The Science The Question The Experiment The Meals The Results The Economics of (Dietary) Information, cont’d Market Problem: In the absence of a market intervention that makes it possible for producers to send credible signals about product quality (standards, certifications, etc.), credence qualities lead to a market breakdown (a.k.a. “Lemons Equilibrium”), in which low-quality goods (in this case, high-GI foods) dominate the market. Personal Problem: So which foods should I eat? Avoiding all processed food is costly. . . so it would be nice to know which products are better or worse. . . for me. The Good News: The cost of measuring one’s blood sugar is falling, making it possible to personally assess individual foods (economic note: thus transforming a credence quality into an experience quality. . . for me). Smith Asymmetric Information 5 / 27
- 20. The Science The Question The Experiment The Meals The Results Measuring Blood Sugar Home test kits are cheap and reliable (this one: $9 at Walmart) Each measurement requires tiny drop of blood and a single-use test strip ($0.43 each) Need to be careful about things that influence blood sugar: exercise, time of day, time since last meal, etc. Smith Asymmetric Information 6 / 27
- 21. The Science The Question The Experiment The Meals The Results The Question What should I eat? GI available for some foods, but not for meals, not for ME. Question, more precisely: what are the foods I eat (or once ate, as a teenager) doing to my blood sugar? Note: Subject is non-diabetic, as confirmed by recent A1c test ($9 single-use kit, Walmart) result of 5.3%. Smith Asymmetric Information 7 / 27
- 22. The Science The Question The Experiment The Meals The Results The Experiment Experimental protocol, in brief: Measure blood sugar before lunch (t = 0). Eat lunch (0 < t < 30 min.). Re-sample blood every 30 minutes, for five hours. Limit exercise during afternoon to short walks down the hall. Take notes. Smith Asymmetric Information 8 / 27
- 23. The Science The Question The Experiment The Meals The Results The Meals Smith Asymmetric Information 9 / 27
- 24. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) Smith Asymmetric Information 9 / 27
- 25. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) 2 Beans: 1 can, rinsed, w/Canola Oil (≈ 950 cal) Smith Asymmetric Information 9 / 27
- 26. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) 2 Beans: 1 can, rinsed, w/Canola Oil (≈ 950 cal) 3 Buttered Bread: Thick-crust Ciabatta (4x) w/plenty of Butter (≈ 1100 cal) Smith Asymmetric Information 9 / 27
- 27. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) 2 Beans: 1 can, rinsed, w/Canola Oil (≈ 950 cal) 3 Buttered Bread: Thick-crust Ciabatta (4x) w/plenty of Butter (≈ 1100 cal) 4 Mac & Cheese: 1 package, w/Olive Oil (≈ 1450 cal) Smith Asymmetric Information 9 / 27
- 28. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) 2 Beans: 1 can, rinsed, w/Canola Oil (≈ 950 cal) 3 Buttered Bread: Thick-crust Ciabatta (4x) w/plenty of Butter (≈ 1100 cal) 4 Mac & Cheese: 1 package, w/Olive Oil (≈ 1450 cal) 5 Beer & Brats: 24oz. Moose Drool, 3 Brats (≈ 1350 cal) Smith Asymmetric Information 9 / 27
- 29. The Science The Question The Experiment The Meals The Results The Meals 1 Fruit & Veggies: Stir-fried Bok Choy, Peanuts, Pear, Carrots (≈ 750 cal) 2 Beans: 1 can, rinsed, w/Canola Oil (≈ 950 cal) 3 Buttered Bread: Thick-crust Ciabatta (4x) w/plenty of Butter (≈ 1100 cal) 4 Mac & Cheese: 1 package, w/Olive Oil (≈ 1450 cal) 5 Beer & Brats: 24oz. Moose Drool, 3 Brats (≈ 1350 cal) 6 Vending Machine: Vanilla Creme Cookies, Potato Chips (3x), Twix, Cherry Coke (1725 cal) Smith Asymmetric Information 9 / 27
- 30. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) Smith Asymmetric Information 10 / 27
- 31. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) Smith Asymmetric Information 10 / 27
- 32. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) Smith Asymmetric Information 10 / 27
- 33. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) 10 Bun (No Burger): 6 Hamburger Buns, Ketchup/Mustard/Pickles (≈ 1100 cal) Smith Asymmetric Information 10 / 27
- 34. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) 10 Bun (No Burger): 6 Hamburger Buns, Ketchup/Mustard/Pickles (≈ 1100 cal) 11 Ice Cream: 1 pint, 24 oz. Shake (≈ 1900 cal) Smith Asymmetric Information 10 / 27
- 35. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) 10 Bun (No Burger): 6 Hamburger Buns, Ketchup/Mustard/Pickles (≈ 1100 cal) 11 Ice Cream: 1 pint, 24 oz. Shake (≈ 1900 cal) 12 Pizza Hut: Medium Pepperoni (Pan Pizza, 6 slices), 22 oz. Root Beer (1780 cal) Smith Asymmetric Information 10 / 27
- 36. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) 10 Bun (No Burger): 6 Hamburger Buns, Ketchup/Mustard/Pickles (≈ 1100 cal) 11 Ice Cream: 1 pint, 24 oz. Shake (≈ 1900 cal) 12 Pizza Hut: Medium Pepperoni (Pan Pizza, 6 slices), 22 oz. Root Beer (1780 cal) 13 Subway (low-fat menu): Footlong Chicken Teriyaki, Yogurt, Baked Lays, Juicebox (872 cal) Smith Asymmetric Information 10 / 27
- 37. The Science The Question The Experiment The Meals The Results The Meals 7 McDonald’s: Quarter Pounder w/Cheese, Large Fries, Med. (21 oz.) Shake (1855 cal) 8 Jack in the Box: Big Cheeseburger, Medium Fries, 16 oz. Shake (1940 cal) 9 Burger (No Bun): Ground Beef (1/2 lb.), Fried Eggs (3x), Cheese (≈ 1150 cal) 10 Bun (No Burger): 6 Hamburger Buns, Ketchup/Mustard/Pickles (≈ 1100 cal) 11 Ice Cream: 1 pint, 24 oz. Shake (≈ 1900 cal) 12 Pizza Hut: Medium Pepperoni (Pan Pizza, 6 slices), 22 oz. Root Beer (1780 cal) 13 Subway (low-fat menu): Footlong Chicken Teriyaki, Yogurt, Baked Lays, Juicebox (872 cal) Which will cause biggest “spike” in blood sugar? Smith Asymmetric Information 10 / 27
- 38. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 11 / 27
- 39. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 12 / 27
- 40. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 13 / 27
- 41. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans Buttered Bread 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 14 / 27
- 42. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans Buttered Bread Mac & Cheese 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 15 / 27
- 43. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans Buttered Bread Mac & Cheese Beer & Brats 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 16 / 27
- 44. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans Buttered Bread Mac & Cheese Beer & Brats Vending Machine 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 17 / 27
- 45. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 18 / 27
- 46. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 19 / 27
- 47. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box Burger No Bun 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 20 / 27
- 48. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box Burger No Bun 200 Bun No Burger 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 21 / 27
- 49. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box Burger No Bun 200 Bun No Burger Ice Cream 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 22 / 27
- 50. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box 200 Pizza Hut 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 23 / 27
- 51. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies McDonald's Jack in the Box 200 Pizza Hut Subway Low Fat 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 24 / 27
- 52. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fruit & Veggies Beans Buttered Bread Mac & Cheese Beer & Brats Vending Machine McDonald's Jack in the Box Burger No Bun 200 Bun No Burger Ice Cream Pizza Hut Subway Low Fat 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 25 / 27
- 53. The Science The Question The Experiment The Meals The Results The Results Blood Glucose, mg dL 250 Fast Food 'Slow' Food 200 150 100 Hours 0 1 2 3 4 5 Smith Asymmetric Information 26 / 27
- 54. The Science The Question The Experiment The Meals The Results . . . A Grain of Salt Caveats: Small subject pool! (n=1) Small number of meal replications! (n=1 in most cases) Best course of action: collect your own data. (and if you do, consider sharing it: trentsmith@wsu.edu) Smith Asymmetric Information 27 / 27
- 55. The Science The Question The Experiment The Meals The Results . . . A Grain of Salt Caveats: Small subject pool! (n=1) Small number of meal replications! (n=1 in most cases) Best course of action: collect your own data. (and if you do, consider sharing it: trentsmith@wsu.edu) Nevertheless, some tentative observations: At best, standard 2-hour GI misses a lot. Fast food is hard to beat if you’re looking for a (blood) sugar high. Be skeptical of health claims. Would the market outcome be different if information about glycemic effects were more widely available? Smith Asymmetric Information 27 / 27