That provocative claim was originally made bay a commentor at the Freakonomics blog. Freakonomics co-author, Stephen Dubner, turned the claim into an interesting podcast for NPR. Then Kyle Smith wrote an editorial on the topic for the New York Post celebrating the McDouble. The Wall Street Journal picked up the story, and predictably, a number of outlets offered a counter-response. It seems the story has gone viral.
If you care to hear my thoughts on the subject, I had to opportunity to briefly expound on it a bit this morning on Fox and Friends.
The one thing I didn't say is that it is not necessarily true that more nutritious food is always more expensive. The USDA published a report on this issue a few months ago. Basically, it comes down to how you measure it. If you measure the cost of nutrition as the price per calorie, then lettuce is going to look really expensive because lettuce doesn't provide many calories. But, if you measure the cost as the price per gram (or pound), then fruits and veggies don't look so costly compared to other foods.
Some people point out that it is more expensive to order a salad than a McDouble at McDonald's. Doesn't that prove it is more expensive to eat healthy? Well, first, a McDonald's salad is not necessarily better for you. It's important to actually look at the nutritional content of salads at McDonald's; you can easily eat more calories by ordering a salad - especially if you add chicken or use salad dressing. But, even if the salad is more nutritious, it is likely more expensive because there is more volume to the salad than the burger (i.e., there are more oz in the serving of salad than burger) so you're getting more with the salad; also, there is the extra storage costs required with the bulkier packaging, not to mention the costs associated with keeping salads fresh and dealing with spoilage and waste.
Finally, on this point, Adam Drewnowski - who was done a lot of research on this topic - sent me this recently published paper, where he calculated the cost of various fruits and veggies according to a nutrient score. I pulled out the second figure from the paper and reproduced it below. If I'm not mistaken, it looks like there is a positive correlation here: the higher the nutrient score, the more affordable the food is.
One take-away from the figure: if you want inexpensive nutrients, eat sweet potatoes!