Table 1.
Characteristics of food price studies included in meta-analysis
| Author, year | Time of price data collection | Participants or foods, setting | Assessment of healthfulness | Price assessment |
|---|---|---|---|---|
| Market studies | ||||
| Cassady et al, 200741* | June 2003, September–October 2003, March–April 2004 | 35 foods from 25 stores in Sacramento and Los Angeles, California | Fruit 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, 20067 | June 2003, September 2003, March–April 2004 | 133 foods from 25 stores in Sacramento and Los Angeles, California | Market 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, 201142 | NR | 131 foods in 8 food categories from 6 stores in Jackson County, Missouri | Nutrition Detectives programme criteria for healthfulness (meeting vs not meeting)¶‡ | Prices collected from chain grocery stores accessible to research assistant |
| Krukowski et al, 201040 | February–April 2008 | 20 foods from 42 stores in Arkansas and Vermont | 10 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, 200743 | 2004 | 8 foods from 75 stores in Orangeburg County, South Carolina | Lean 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 milk | All 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, 200944 | 2008 | 2 food groups from 1 store in mid-Atlantic region | Produce (fruits, vegetables) vs snacks (cookies, chips) | Price collected from online supermarket |
| McDermott and Stephens, 20108 | NR | 34 foods from 4 stores in Baltimore, Maryland | 3 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 restaurant | Prices for healthier foods obtained from 3 large supermarket chains. Prices for less healthy foods obtained from a large, multinational fast-food chain |
| Ricciuto et al45 | November 2002 | 229 foods from 9 stores in Toronto, Canada | Margarine with vs without label ‘low in saturated fat’ or ‘cholesterol free’ | Prices obtained from 9 stores of 3 major chain supermarkets |
| Ricciuto et al46 | November 2002 and November–December 2006 | 229 foods from 9 stores in 2002 and 274 foods from 10 stores in 2006 in Toronto, Canada | Trans fat-free vs non-trans fat-free margarine†† | Prices obtained from 10 stores of 3 major chain supermarkets |
| Temple and Steyn39 | May 2006 | 24 foods from 1 store in each of 3 communities in Cape Town, South Africa | Higher-fibre, lower-fat, and lower-sugar daily menu vs typical daily menu‡‡ | Food prices obtained from supermarkets; price reported by community |
| Wang et al, 201047 | June–August 2005 | 14 foods from 1230 stores in Waikato and Lakes Districts, New Zealand | Basket 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, 200548 | January 23, 2005 | 18 foods from 2 stores in Wellington, New Zealand | Basket 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, 201138 | April–June 2004 and May–July 2006 | 1266 participants in Seattle Obesity Study; 3 stores | Dietary 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, 20106 | 2001–2002 | 78 191 participants in Nurses’ Health Study; 467 foods | Alternative 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, 200419 | NR | 837 participants in Val-de-Marne, France; 57 foods | Fats 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, 200949 | December 1999–May 2005 | 11 195 participants in Spain; 136 foods | Western 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, 200950 | May–July 2006 | 164 participants; 384 foods from 3 stores in Seattle, Washington | Dietary 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, 201251 | April–June 2004 and May–July 2006 | 1295 participants; 384 foods from 3 stores in Seattle, Washington | Nutrient 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, 201237 | 2003–2004 | 1294 snack-days in 32 YMCA after-school programmes in 4 metropolitan areas | Environmental Standards for Healthy Eating (meeting vs not meeting)¶¶¶ | Prices from USDA Center for Nutrition Policy and Promotion price database |
| Murakami et al, 200952 | 2004 | 596 pregnant women in Neyagawa City, Osaka Prefecture, Japan; 150 foods | Dietary 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, 200953 | NR | 346 children aged 3–4 years; 3 brands each of 104 foods from 2 stores in São Leopoldo, Brazil | Calories 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, 20119 | 2001–2002 | 4744 participants in NHANES | Healthy 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, 200854 | Autumn 2005 | 30 participants in Kalmar province, Sweden; 600 foods | Mediterranean 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, 201110 | Spring 2010 | 2160 children ages 4, 8, and 11 y in Sweden; prices of 991 foods from Statistics Sweden, and stores when not available from Statistics Sweden | Healthy 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, 200655 | May 2005 | 2847 participants in Girona, Spain; 165 foods | Mediterranean 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, 200956 | 2006 | 112 participants; 8 stores in San Joaquin, Solano, Calavaras, and Tulare counties in California | Dietary 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, 201057 | February–April 2008 | 373 participants in Longitudinal Ageing Study Amsterdam and 200 participants in Amsterdam Growth and Health Longitudinal Study; 2 stores | Dietary 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.