Food choices and diet costs: An economic analysis

Transcription

1 Food choices and diet costs: An economic analysis Adam Drewnowski, PhD Director, Center for Public Health Nutrition Director, NIH Roadmap Center for Obesity Research Professor of Epidemiology and Medicine School of Public Health and Community Medicine University of Washington Poverty and Obesity: Disparities in Diet and Health. ECOR Interdisciplinary Forum, Seattle, WA, March 2, 2007

2 Disparities in diet and health: A new focus on money and time Some basic points: Energy-dense foods cost less Nutrient-rich rich foods cost more Healthier diets cost more per MJ There are inequities in food access Consumer food choices are driven by Taste, cost, convenience, health, variety

3 Consumers care about food costs

4 Some health professionals do not

5 Are healthy diets available to all? The Harvard SPH Food Pyramid Is this the perfect diet or is it economic elitism?

6 Taste, cost, convenience = sugar + fat Grains, Energy density Sugar/fat Sugar/fat Taste Grains, Cost Sugar/fat Obesity Food choices Obesity Grains, Time/Convenience Sugar/fat Health Variety

7 First question Do energy-dense foods cost less? Energy density defined as MJ/kg Energy cost defined as $/MJ ( /MJ)( Energy and nutrients from databases Mean national food prices in France

8 Energy density (MJ/kg) depends on the water content of foods 40 oil Fats Sw eets Grains Vegetables Fruit Meat Dairy Energy density (MJ/kg) grains Potato chips butter meats fruit vegetables w ater content (g/100g)

9 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) spreads Log scale! Energy cost (Euros/1000kcal)

10 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar desserts 200 soft drinks Energy cost (Euros/1000kcal)

11 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains bread desserts 200 pasta soft drinks Energy cost (Euros/1000kcal)

12 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains cheese desserts 200 pasta yogurt milk Energy cost (Euros/1000kcal)

13 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains cheese 200 desserts pasta meat milk Energy cost (Euros/1000kcal)

14 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains cheese foie gras 200 desserts pasta meat fish/shellfish milk Energy cost (Euros/1000kcal)

15 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains cheese 200 desserts pasta meat fish/shellfish milk vegetables Energy cost (Euros/1000kcal)

16 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains desserts nuts cheese fruit 200 pasta fish/shellfish milk vegetables Energy cost (Euros/1000kcal)

17 Energy density (kcal/100g) and energy cost (Euros/1000kcal) INCA study 1000 oil 800 butter Energy density (kcal/100g) sugar grains desserts nuts cheese fruit Wine/alcohol 200 pasta fish/shellfish milk vegetables Energy cost (Euros/1000kcal)

18 1000 Disparity in food costs: Are junk foods simply cheaper? oil Energy density (kcal/100g) butter High glycemic Index High glycemic load Hydrogenated fats Trans fatty acids Added sugars Added fats Energy sugar dense foods Empty calories Minimal nutritional value grains Low energy density High satiating power Antioxidants Phytochemicals Fiber CLA Vitamins Minerals 200 desserts fruit fish soda vegetables Energy cost (Euros/1000kcal)

19 Second question Are energy-rich rich foods nutrient-poor? Energy-dense foods cost less Grains, fats, oils are more affordable Energy-dense foods taste better Palatability = energy density Are low-cost, energy-dense foods low in key nutrients?

20 We need to create a nutrient density score for foods: Nutrient Density Score is the ratio between the amount of nutrients in a food and the energy that the food provides NDS = (NAS/ED) * 100 Nutrient Adequacy Score is based on percent DVs for N key nutrients as provided by 100 g of food NAS = (Σ (Nutrient i /DV i ) * 100)/N Nutrient-to-price ratio NPR = NAS/price per 100g Work by Darmon,, Drewnowski, Monsivais

21 Yes energy dense foods have lower Nutrient Density Scores (NDS/100kcal) Fats/oils Energy Density (kcal/100g) sugar F+V Nutrient Density Score/100 kcal Darmon, Darmon, Maillot, Drewnowski JADA 2005

22 Higher nutrient-density (per 100g) usually means higher cost (also per 100g) 1000 Nutrient Adequacy Score/100g All foods F+V Price (Euros/100g) Darmon, Darmon, Maillot, Drewnowski JADA 2005

23 NNR scores for vegetables and fruit 40 vegetables fruit Energy density (MJ/kg) applesauce grape juice potato chips fried potatoes raisins OJ potatoes canned pears avocado blueberries cantaloupe mango tangerines strawberries grapefruit kiwi spinach romaine broccoli tomato Nutrient Density Score (NNR version)

24 Third question: Do energy-dense diets cost less? French INCA study conducted by AFSSA Sample of 1,985 adults; 7-day 7 food diaries National prices for 650 foods Diet costs measured in /d Energy cost measured in /10MJ

25 At each intake quintile, higher energy density = lower cost ( /wk) Diet cost (Euros/week) INCA data EI Energy density (KJ/g)

26 At each intake quintile, higher energy density = lower cost ( /wk) Diet cost (Euros/week) INCA data EI 2 EI Energy density (KJ/g)

27 At each intake quintile, higher energy density = lower cost ( /wk) Diet cost (Euros/week) INCA data EI 3 EI 2 EI Energy density (KJ/g)

28 At each intake quintile, higher energy density = lower cost ( /wk) Diet cost (Euros/week) INCA data EI 4 EI 3 EI 2 EI Energy density (KJ/g)

29 At each intake quintile, higher energy density = lower cost ( /wk) Diet cost (Euros/week) INCA data EI 5 EI 4 EI 3 EI 2 EI Energy density (KJ/g)

30 Spend less = Eat more Are obesity and poverty linked by the low cost of energy- dense foods that are both palatable and convenient? Drewnowski & Specter, Am J Clin Nutr 2004;79:6-16

31 The Energy Density curve Drewnowski and Specter AJCN 2004:79: Sugar fat Low quality High quality Energy density Food energy requirement 0 Food energy Food costs (log) The paradox it is possible to spend less and get more But the calories will be refined grains, added sugar and fat

32 As dietary ED increases so do total energy intakes 10 9 Energy density (KJ/g) INCA data Energy intake (MJ/week)

33 Last question: What happens when you stratify diets by energy cost? Food expenditures can be a proxy for SES

34 An epidemiological dogma falls The unshakeable relationship between nutrients and calories disappears

35 A principle of nutritional epidemiology Intakes of virtually all nutrients are positively correlated with total caloric intake People who consume more total food have higher nutrient intakes Nutrient intakes are biologically important in relation to caloric intakes Hence the need to correct for energy in epidemiologic studies Willett and Stampfer in Nutritional Epidemiology, 2 nd Ed, OUP 1998

36 The INCA (1998) data set INCA is a nationally representative study of 1,985 French adults Dietary intakes based on 7-day diet records. More than 850 foods in the nutrient database Mean national food prices supplied by the French government (INSEE); by market research agencies (SECODIP), as well as Paris websites Diet costs estimated by multiplying unit price for each item by portion size and summing over all foods consumed by that person That is the estimated cost of the diet assuming that all foods are purchased and prepared at home

37 Low-cost diets: Spend less but eat more Quartiles of energy cost ( /10MJ) P Anova Q1 (4.9) Q2 (5.9) Q3 (6.9) Q4 (9.0) Energy Density (MJ/kg) Energy Intake (MJ/d) Vitamin C (mg/day) Vitamin D (µg/day) Vitamin E (mg/day) ß-Carotene (mg/day) Folates (µg/day) Andrieu, Darmon,, Drewnowski, EJCN, 2006

38 Low cost diets: more energy, fewer nutrients % of Q Referent diet Q1 Q2 Q3 Q4 4.9 /10MJ 5.9 /10MJ 6.9 /10MJ 9.0 /10MJ 4.5 /d 5.3 /d 6.0 /d 7.4 /d Vitamin C Vitamin D ß Carotene Folates Vit E Energy Intake Energy Density

39 Val-de de-marne: Contribution of food groups to diet energy and to diet cost (Drewnowski & Darmon, AJCN, 2005) % diet cost % dietary energy Meat/Fish F+V Dairy Grains Sugar Fats/oils The energy/price hierarchy is such that the lowest-cost food groups contribute the most to energy intakes

40 Final question: What about food prices in Seattle? We collected food prices in 2004 and 2006 Same supermarkets, same foods, same package sizes The foods were divided by energy density Low ED = vegetables and fruit High ED = grains, sugars and fats Manuscript (Monsivais et al.) submitted to JADA

41 Energy density (kcal/100g) and energy cost ($/1000kcal) Seattle 2006 Supermarket prices 10 oil 8 butter Energy density (kcal/100g) 6 4 sugar grains desserts nuts cheese fruit 2 pasta fish/shellfish milk vegetables Energy cost ($/1000kcal)

42 The rising cost of low-energydensity foods Fruits and vegetables Fats and sweets Price Inflation (%) * ] ] ] ] ] Quintiles of Energy Density Monsivais et al. submitted

43 Access to healthy foods Affordability Energy-dense foods are cheaper Accessibiity Energy-dense foods are closer Convenience Fast foods take less time to prepare

44 What can you get for $100/week for a family of 4. The USDA Thrifty Food Plan: oil shortening zucchini squash Energy density (MJ/kg) margarine mayonnaise crackers sugar white bread beans eggs cheese ground beef green peppers lettuce fresh tomatoes 0 potatoes milk koolaid Energy cost (log cents/10mj)

45 Is obesity an economic issue?

46 A challenge for public health nutrition Less expensive More expensive High-fat energy-dense foods are often the cheapest options for the consumer Editorial, The Lancet January 31, 2004 If a meal of grilled chicken, broccoli and fresh fruit costs more and is less convenient than a burger and fries, the battle against obesity will be lost Editorial, The Lancet January 31, 2004

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48 Food choices and diet costs: An economic analysis Adam Drewnowski, PhD Director, Center for Public Health Nutrition Director, NIH Roadmap Center for Obesity Research Professor of Epidemiology and Medicine School of Public Health and Community Medicine University of Washington Poverty and Obesity: Disparities in Diet and Health. ECOR Interdisciplinary Forum, Seattle, WA, March 2, 2007