Is "healthy food" so expensive?

The adoption of healthy food choices is limited by many barriers, including economic constraints and lack of nutrition knowledge. In observational studies, healthy diets were shown to be more expensive than less healthy diets (1;2). This has been attributed to the high cost of energy in nutrient-dense foods such as fruit, vegetables, fish and lean meats, whereas energy-dense nutrient-poor foods are the least expensive sources of dietary energy (3). On the other hand, intervention studies implicating nutrition education have shown that increasing dietary quality does not necessarily increase diet costs (4-6). In addition, diet modeling studies have shown that, while cost constraints induce the selection of energy-dense nutrient-poor diets (7), it is possible to select a nutritious diet at a very low cost (8). A large body of evidence suggests, therefore, that nutrition knowledge may counteract, at least in part, the negative aspect of economic constraints on food choices. However, to translate this theory into practice, consumers willing to eat healthily at a low cost will need to know which foods provide a good nutrient value for their unit cost.

One strategy employed by the poorest households to reduce their expenditure on food is to reduce consumption of the food groups which are the most expensive sources of energy, such as fruit, vegetables and fish, whilst preferring to eat foods which are a cheap source of energy, such as refined cereals, cheap cuts of meat and fatty and sugary products. However, such food «choices» are associated with a severe reduction of the nutritional quality of their diets (7). Another strategy is to choose low-cost foods within a given product category and/or to shop at discount stores. This could be a good way to obtain a balanced diet at a cheaper price, since existing studies have failed to show any difference in nutritional quality between low-cost and branded products (9;10).

Another strategy would be to select preferentially those foods that have a good nutritional quality relative to their price. Nutrient profiling systems may help consumers to identify such foods. This concept has been initially proposed by the European Commission for a regulation on nutrition and health claims (11), but it can be used for different purposes, including nutrition information and education. The nutrient profile of a given food is, in fact, a synthetic indicator of its global nutritional quality. Using such approach, it has been confirmed that, as a whole, the meat and fruit and vegetables food groups had the highest nutritional quality and the highest energy costs, whereas sweets and salted snacks had the lowest nutritional quality and were the least expensive sources of dietary energy. Starches and grains were unique because they had a low content in disqualifying nutrients yet they provide low-cost dietary energy. Interestingly, within each major food group, some subgroups had a higher nutritional quality to price ratio than others. In particular, milk, organ meats, and eggs, had a very good nutritional quality to price ratio. Vegetable fats, dried fruit and nuts also showed good nutritional quality to price ratios.

It is interesting to note that diets obtained with a computer in order to respect the whole set of nutritional recommendations at the lowest cost preferentially contained foods belonging to the groups and subgroups identified by nutrient profiling as having good nutritional quality to price ratios (8). However, the fact that food groups with the more favorable nutrient profiles were also associated with higher energy costs suggests that the present structure of food prices may be a barrier to the adoption of food-based dietary guidelines, at least by low-income households.

References:

1. Cade J, Upmeier H, Calvert C, Greenwood D. Costs of a healthy diet: analysis from the UK Women’s Cohort Study. Public Health Nutr 1999;2:505-12.

2. Darmon N, Briend A, Drewnowski A. Energy-dense diets are associated with lower diet costs: A community study of French adults. Publ Health Nutr 2004;7:21-7.

3. Drewnowski A, Darmon N, Briend A. Replacing fats and sweets with vegetables and fruit – a question of cost. Am J Pub Health 2004;94:1555-9.

4. Raynor HA, Kilanowski CK, Esterlis I, Epstein LH. A cost-analysis of adopting a healthful diet in a family-based obesity treatment program. J Am Diet Assoc 2002;102:645-56.

5. Burney J, Haughton B. EFNEP: a nutrition education program that demonstrates cost-benefit. J Am Diet Assoc 2002;102:39-45.

6. Mitchell DC, Shannon BM, McKenzie J, Smiciklas-Wright H, Miller BM, Tershakovec AM. Lower fat diets for children did not increase food costs. Journal of Nutrition Education 2000;32:100-3.

7. Darmon N, Ferguson EL, Briend A. A cost constraint alone has adverse effects on food selection and nutrient density: an analysis of human diets by linear programming. J Nutr 2002;132:3764-71.

8. Darmon N, Ferguson EL, Briend A. Impact of a cost constraint on nutritionally adequate food choices for French women: an analysis by linear programming. J Nutr Educ Behav 2006;38:82-90.

9. Cooper S, Nelson M. ‘Economy’ line foods from four supermarkets and brand name equivalents: a comparison of their nutrient contents and costs. J Hum Nutr Diet 2003;16:339-47.

10. Joly C, Maillot M, Caillavet F, Darmon N. Aliments premier prix : peut-on les comparer aux aliments de marque ? P108, Nutr Clin Métab, 2007; 20, S151.

11. The European Parliament and the Council of the European Union. Regulation (EC) No 1924/2006 of the European Parliament and of the Council of 20 December 2006 on nutrition and health claims made on foods. Official Journal of the European Union 2006;L 404:9-25.