Wednesday, September 29, 2010

Told to Eat Its Vegetables, America Orders Fries

New York Times article "Told to Eat Its Vegetables, America Orders Fries" (September 24th, 2010) gives potentially misleading statistics about vegetable-consumption in the United States and fails to tell a cohesive story about the incentives for healthy eating.
At restaurants, salads ordered as a main course at either lunch or dinner dropped by half since 1989, to a mere 5 percent, he said.
The profile of diners has changed significantly since 1989, making the average number of salads ordered at restaurants incomparable over time. This is because among modern diners, those who would have ordered salad if they were transported to 1989 may continue to order salad, making the mean number of salads ordered among this group constant between 1989 and 2010. However, this group does not include all restaurant go-ers. Some people who eat out today may not have done so in 1989.

Even if we believe that the population of restaurant goers is unchanged, some meals eaten out would not have been eaten out in 1989 because the number of meals eaten away from home has increased. According to a 1999 study in the Family Economics and Nutrition Review, titled "Contribution of Away-From-Home Foods to American Diet Quality" (available here), between 1989 and 1995, the percentage of meals eaten away from home increased by five percentage points (more than 20%) even though the number of meals eaten daily was unchanged. A graph of the trend is included below (click here to enlarge).

To its credit, the article makes some note of the difference between consumption trends in different demographic groups. What is missing is a solid economic interpretation.

To be sure, vegetables are making strides in certain circles. Women, as well as people who are older and more educated and have higher incomes, tend to eat more vegetables, said Dr. Foltz, the pediatrician who worked on the C.D.C. report.
Vegetables are commodities that cost a great deal in the short-run, but pay off in the long-run. We can think of the true price of vegetables as lower than the market price, since they make people richer in terms of health. Because the length of life (and productivity) is a function of health, avoiding vegetables costs those who make higher wages more (they lose more lifetime income by dying early from unhealthy eating). So, the total price of vegetables is lower for the wealthy than the poor, even though the market price is the same. We can also expect that health is a stronger determinant of life-span in later years, so the elderly, as well as women (who live longer than men on average) can be expected to consume more vegetables.

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