I’ve had a chance to read the recent Economic Research Service report called “Are Healthy Foods Really More Expensive?”, written by Carlson and Frazao. The main finding of the research is that whether healthy foods are more expensive depends on the measurement of both the healthfulness of food, and then the per unit cost of the metric of healthfulness. The researchers reached these conclusions through a comparison of per unit costs to assess whether healthy food is more expensive. The metrics selected were (1) price per calorie, (2) price of edible weight (ie, not the pounds purchased, but the pounds available after the food is prepared or eaten; for example, the weight of melon rinds would be subtracted from the total weight purchased), (3) price of an average sized portion, and (4) cost of meeting the most recent dietary guidelines.
Previous research measured price in terms of $$ per calorie; the body of work largely examines the “nutrition transition” in developing countries, which describes the evolution from a diet based on low cost grains or starchy vegetables, to one based on more costly animal products, vegetables, and convenience foods. While the bulk of this work has been conducted by development economists, recent work by nutritionists has also been rooted in the price per calorie.
The previous literature received three main criticisms: (1) food that is high in calories, but is not healthy, has a low price per calorie; (2) price per calorie does not reflect the total cost of someone’s diet; and (3) people don’t actually seek low cost per calorie; if they did, the marketing claims of “low in calorie” would send consumers a signal that the food is too expensive, which would suggest manufacturers would not use this marketing claim (but in fact, they do!).
The metrics used to approximate the cost of food are a direct rebuttal to the criticisms levied on the “price per calorie” model. Each measure attempts to address one shortcoming of the price per calorie.
Using the National Health and Nutrition Examination Study data from 2003-04, Carlson and Frazao examine the relative costs of healthy/unhealthy food using the four metrics. The work clearly required a serious amount of data preparation. I admire their tenacity, because they must have spent more than a year preparing the data for this work.
From a shopping perspective, I believe consumers buy food to prepare meals, and thus are more concerned with overall cost of their diet (roughly speaking). I doubt people think about the cost per calorie, unless they are severely income constrained and need to budget to purchase enough calories. Beyond this, behavioral economics tells us that eating (and consequently buying) food is not always predictable. But brushing aside the implications of behavioral economics, two of the methods they suggest seem most reasonable: cost per serving and cost of meeting dietary guidelines.
In the end, the authors analyze a significant amount of data regarding the cost of food, by type (vegetable, fruit, grain, etc). Cost per 100 calories, cost per average portion, and costs per 100 grams of edible weight are estimated and compared. They show that low calorie foods are more expensive per calorie than are high calorie foods, but that cost per 100 gram of edible weight or portion size is lower for lighter foods (such as vegetables). In other words, high calorie (less nutrious?) foods probably weigh more than low calorie foods. This means that dairy products, when compared to fruit or vegetables, are more expensive in terms of weight or portion size than they are in terms of calories.
While I greatly admire the work of the authors (it is creative, time intensive, and has painstaking attention to detail), I would have found the study to be more intuitive if the comparisons were made across a range of healthy and unhealthy diets. For example, why not compare the costs of the following? A vegetarian diet, a meat-based but healthy diet, processed vs fresh foods, the standard American diet, etc. Further, the diets could be adapted to be culturally appropriate to different ethnic groups residing in the U.S.
An analysis based on how people really eat rather than artificial measures of costs, disconnected from a real person’s diet, would better inform us about the true relative monetary costs of consuming healthy and unhealthy diets. That type of analysis would better inform policy that addresses the public health consequences of unhealthy diets, and would give policymakers deeper knowledge about which policy levers might alter individual food choices.