Table 1

Characteristics of food price studies included in meta-analysis

Author, yearTime of price data collectionParticipants or foods, settingAssessment of healthfulnessPrice assessment
Market studies
 Cassady et al, 200741*June 2003, September–October 2003, March–April 200435 foods from 25 stores in Sacramento and Los Angeles, CaliforniaFruit and vegetable basket meeting 2005 Dietary Guidelines vs 1995 Thrifty Food Plan fruit and vegetable basket†‡Cross-sectional price survey conducted across 3 time periods in chain supermarkets, small independent grocery stores, and supermarkets selling bulk food items with no membership fee
 Jetter and Cassady, 20067June 2003, September 2003, March–April 2004133 foods from 25 stores in Sacramento and Los Angeles, CaliforniaMarket basket with four times the amount of fibre and one-fifth the grams of total fat vs 1995 Thrifty Food Plan market basket§Cross-sectional price survey conducted across 3 time periods in chain supermarkets, small independent grocery stores, and supermarkets selling bulk food items with no membership fee
 Katz DL et al, 201142NR131 foods in 8 food categories from 6 stores in Jackson County, MissouriNutrition Detectives programme criteria for healthfulness (meeting vs not meeting)¶‡Prices collected from chain grocery stores accessible to research assistant
 Krukowski et al, 201040February–April 200820 foods from 42 stores in Arkansas and Vermont10 high-fibre, low-fat, low-sugar foods vs 10 low-fibre, high-fat, high-sugar foods**Overweight individuals entering a behavioural weight loss research programme self-reported their primary grocery store. Trained data collectors assessed food prices at these stores
 Liese et al, 20074320048 foods from 75 stores in Orangeburg County, South CarolinaLean ground beef vs high-fat ground beef; skinless and boneless chicken breasts vs chicken drumsticks; high-fibre bread vs low-fibre bread; low-fat/non-fat milk vs whole milkAll food stores in county identified from Licensed Food Service Facilities Database and in-person verification. Prices recorded and reported by store type (supermarket, grocery store, convenience store)
 Lipsky, 20094420082 food groups from 1 store in mid-Atlantic regionProduce (fruits, vegetables) vs snacks (cookies, chips)Price collected from online supermarket
 McDermott and Stephens, 20108NR34 foods from 4 stores in Baltimore, Maryland3 cups milk/dairy, 5 oz lean meat, 1.5 c fruit, 2.5 cups vegetables, and 6 oz grains per day vs breakfast, lunch, and dinner from fast-food restaurantPrices for healthier foods obtained from 3 large supermarket chains. Prices for less healthy foods obtained from a large, multinational fast-food chain
 Ricciuto et al45November 2002229 foods from 9 stores in Toronto, CanadaMargarine with vs without label ‘low in saturated fat’ or ‘cholesterol free’Prices obtained from 9 stores of 3 major chain supermarkets
 Ricciuto et al46November 2002 and November–December 2006229 foods from 9 stores in 2002 and 274 foods from 10 stores in 2006 in Toronto, CanadaTrans fat-free vs non-trans fat-free margarine††Prices obtained from 10 stores of 3 major chain supermarkets
 Temple and Steyn39May 200624 foods from 1 store in each of 3 communities in Cape Town, South AfricaHigher-fibre, lower-fat, and lower-sugar daily menu vs typical daily menu‡‡Food prices obtained from supermarkets; price reported by community
 Wang et al, 201047June–August 200514 foods from 1230 stores in Waikato and Lakes Districts, New ZealandBasket including bread, chicken, beef/pork, sugar-sweetened drinks, milk, snacks, spreads, and sugar meeting vs not meeting New Zealand food-based dietary guidelines (ie, less energy-dense; lower-fat, salt and sugar; and higher-fibre)‡Prices obtained from 1230 stores (including supermarkets, dairies, bakeries, service stations, restaurants and takeaways). Each food was not available in every store
 Wilson and Mansoor, 200548January 23, 200518 foods from 2 stores in Wellington, New ZealandBasket of foods including butter, butter/vegetable oil blend, margarine type spread, cream cheese, hard cheese, grated cheese, cream, biscuits & crackers and chocolate with mean saturated fat of 14.9 g/100 g vs basket of same foods with mean saturated fat of 29.0 g/100 g‡ §§Within each of 9 food-types, items with highest and lowest levels of saturated fat identified and prices obtained from 2 large supermarkets
Dietary studies
 Aggarwal et al, 201138April–June 2004 and May–July 20061266 participants in Seattle Obesity Study; 3 storesDietary energy density, kJ/g and mean adequacy ratio (quintile 1 vs quintile 5)¶¶Diet cost calculated based on prices of FFQ component foods. Food prices obtained from 3 supermarket chains via in-store visits and websites
 Bernstein et al, 201062001–200278 191 participants in Nurses’ Health Study; 467 foodsAlternative Healthy Eating Index score (quintile 5 vs quintile 1)***Diet cost calculated by merging FFQ database with USDA Center for Nutrition Policy and Promotion price database
 Drewnowski et al, 200419NR837 participants in Val-de-Marne, France; 57 foodsFats and sweets intake, fruit and vegetables intake, total fat intake, and sucrose intake (quintile 1 vs quintile 5)Diet cost calculated from food prices from French National Institute of Statistics
 Lopez et al, 200949December 1999–May 200511 195 participants in Spain; 136 foodsWestern dietary pattern score and Mediterranean dietary pattern score (quintile 1 vs quintile 5)†††Diet cost calculated from food prices from Ministry of Industry, Tourism and Commerce of Spain. When data not available from ministry, food prices obtained from national supermarket websites
 Monsivais and Drewnowski, 200950May–July 2006164 participants; 384 foods from 3 stores in Seattle, WashingtonDietary energy density, kcal/g (tertile 1 vs tertile 3)Diet cost calculated based on prices of FFQ component foods. Prices obtained at supermarket chains. Price reported separately for men and women
 Monsivais et al, 201251April–June 2004 and May–July 20061295 participants; 384 foods from 3 stores in Seattle, WashingtonNutrient density of diet (quintile 5 vs quintile 1 of diet cost)‡‡‡ §§§Diet cost calculated based on prices of FFQ component foods. Food prices obtained from 3 supermarket chains via in-store visits and websites
 Mozaffarian et al, 2012372003–20041294 snack-days in 32 YMCA after-school programmes in 4 metropolitan areasEnvironmental Standards for Healthy Eating (meeting vs not meeting)¶¶¶Prices from USDA Center for Nutrition Policy and Promotion price database
 Murakami et al, 2009522004596 pregnant women in Neyagawa City, Osaka Prefecture, Japan; 150 foodsDietary energy density, kcal/g (quartile 4 vs quartile 1 of diet cost)‡‡Diet cost based on National Retail Price Survey. For foods not in survey, prices obtained from websites of nationally distributed supermarket or fast-food restaurant chains
 Rauber and Vitolo, 200953NR346 children aged 3–4 years; 3 brands each of 104 foods from 2 stores in São Leopoldo, BrazilCalories from sugar-rich foods (≤150 vs >150 kcal) and calories from fat-rich foods (≤150 vs >150 kcal)Diet cost based on prices obtained at a large establishment (supermarket or hypermarket) and a small establishment (market, minimart or bakery)
 Rehm et al, 201192001–20024744 participants in NHANESHealthy Eating Index-2005 score (quintile 5 vs quintile 1 of diet cost)‡‡‡ ****Diet cost calculated from USDA Center for Nutrition Policy and Promotion price database
 Rydén et al, 200854Autumn 200530 participants in Kalmar province, Sweden; 600 foodsMediterranean diet vs typical diet††††Diet cost calculated from prices from Statistics Sweden. For foods not reported by Statistics Sweden, prices obtained from 4 stores and 2 online stores
 Rydén and Hagfors, 201110Spring 20102160 children ages 4, 8, and 11 y in Sweden; prices of 991 foods from Statistics Sweden, and stores when not available from Statistics SwedenHealthy Eating Index-2005 score (>70 vs <50)****Average national prices of 391 foods obtained from Statistics Sweden. Prices of remaining 600 foods were not available from Statistics Sweden; obtained from one online supermarket and one online grocery store
 Schroder et al, 200655May 20052847 participants in Girona, Spain; 165 foodsMediterranean Diet Score and Healthy Eating Index score (quartile 4 vs quartile 1)**** ‡‡‡‡Diet cost calculated from average national price database of the Secretaria de Estado de Turismo y Comercio de Espana
 Townsend et al, 2009562006112 participants; 8 stores in San Joaquin, Solano, Calavaras, and Tulare counties in CaliforniaDietary energy density, kcal/g (tertiles 1 vs 3)Diet cost (with and without beverages) calculated based on prices of FFQ component foods. Prices obtained from a large supermarket chain store and a small independent market in each county
 Waterlander et al, 201057February–April 2008373 participants in Longitudinal Ageing Study Amsterdam and 200 participants in Amsterdam Growth and Health Longitudinal Study; 2 storesDietary energy density, kJ/g (quartiles 1 vs 4)Diet cost calculated from prices obtained from 2 market leader supermarkets. Price reported separately for men and women
  • *This study is not included in analysis since it is the only market survey on fruits and vegetables.

  • †Baskets include varying amounts of fruits, dark green vegetables, orange vegetables, legumes, starchy vegetables, and ‘other’ vegetables.

  • ‡Components of baskets also compared.

  • §Baskets include healthier versus less healthy breads, canned fruit, cheese, chicken, cereal; cooking oil, egg noodles, evaporated milk, flour, potatoes; frozen fish; ground meat, milk, rice, salad dressing, spaghetti, margarine and tuna fish. Baskets also include fresh fruits and vegetables, eggs, and beans which are unchanged between two baskets.

  • ¶Nutrition detectives criteria: subjectively determined to not have excessive marketing-related claims or images on the front of the package; not have an unhealthy ingredient such as sugar or white flour listed first on ingredient list, does not contain partially hydrogenated oil or high-fructose corn syrup, and does not have a long ingredient list relative to other items in the same food category. For grain-based products only, more nutritious foods also contain at least 2 g fibre per serving.

  • **Baskets include healthy versus less healthy juice, hot dogs, ground beef, chips, bread, soda, milk, frozen dinner, baked goods and cereals.

  • ††Trans fat-free defined as containing (1) ≤0.2 g TFA per 10 g; (2) ≤2 g TFA and SFA combined per 10 g; and (3) ≤15% energy from TFA and SFA combined per 10 g.

  • ‡‡Typical menu includes corn flakes, whole milk, sugar and cola drink in the morning; white bread, brick margarine, jam and cookies for lunch; and regular hamburger, white rice, fried cabbage and candied butternut for dinner. Healthier menu includes bran flakes, skim milk, banana and orange juice in the morning, whole wheat bread, tub margarine, low-fat cottage cheese and apple for lunch; and lean hamburger, brown rice, boiled cabbage and boiled butternut for dinner.

  • §§Average price at the two stores calculated and used in meta-analysis.

  • ¶¶Model 3 coefficients in tables 4a and b from the paper by Aggarwal et al38 used to calculate difference in price between quintiles 1 and 5. Mean adequacy ratio is a truncated index of the per cent of daily recommended intakes for key nutrients. Computed by taking the average of nutrient adequacy ratio for 11 key nutrients: vitamins A, C, D, E and B12, calcium, iron, magnesium, potassium, folate and fibre. Expressed as percentage of adequacy/day.

  • ***The Alternative Healthy Eating Index reflects intake of fruits, vegetables, nuts, soy, beans, white and red meats, cereal fibre, trans unsaturated fatty acids, polyunsaturated fatty acids, SFAs, alcohol and years of multivitamin use.

  • †††Food items identified in Western pattern were red meat, processed meats, eggs, sauces, precooked food, fast-food, caloric soft drinks, whole-fat dairy and potatoes. Food items identified in the Mediterranean pattern included olive oil, poultry, fish, low-fat dairy, legumes, fruits and vegetables.

  • ‡‡‡Healthfulness of diet stratified by quantile of diet cost.

  • §§§Nutrient density is defined as mean percentage daily value for vitamins A, C and E, calcium, magnesium, potassium and dietary fibre in 2000 kcal of dietary energy.

  • ¶¶¶Environmental Standards for Healthy Eating guidelines: do not serve sugar-sweetened beverages, serve water every day, serve a fruit and/or vegetable every day, do not serve foods with trans fat and when serving grains (such as bread, crackers and cereals) serve whole grains.

  • ****Healthy Eating Index is a measure of overall diet quality based on consumption of sodium, saturated fat, total fruit, whole fruit, total vegetables, dark green and orange vegetables, milk, total grains, whole grains, meat and beans, oils and empty calories.

  • ††††Mediterranean diet included eating more fruits, vegetables and pulses; choosing whole-grain products; changing dietary fat intake to products containing less saturated fat and more unsaturated fat; avoiding meat and meat products; and limiting the intake of sweets, snacks and desserts.

  • ‡‡‡‡Mediterranean diet based on intake of cereals, fruits, vegetables, legumes, fish, olive oil, nuts and red wine.

  • SFA, saturated fatty acid; TFA, trans-fatty acid; NHANES, National Health and Nutrition Examination Survey; USDA, United States Department of Agriculture; YMCA, Young Men's Christian Association.