From the Archives: The Sabermetrics of Lettuce
Some ideas are too good to stay in the dustbin. Here's an old piece of mine I think you'll like, and there'll be another every other week.
This piece was originally published at LinkedIn.
Why do we eat lettuce? First, it’s 96% water and grown in California and Arizona who have water availability issues. That aside, other than taste, how can we decide what makes sense to eat? Here’s an economics view taken from baseball statistics.
A typical salad contains about 3 ounces of lettuce, and, for a restauranteur, it can make a lot of sense to make a huge portion of the salad from lettuce. The average price of lettuce is about $1.35 per pound in 2023, so that the lettuce in your salad costs about a quarter. Once you exclude all of the other costs of labor delivery, and rent, etc. in your restaurant salad, the cost of all ingredients in a $15 salad is about $4.68 (about 31% of the total). So, 3 ounces of lettuce is less than 2% of the cost of ingredients. As they add more lettuce, the profit margin goes up. Given its nutritional value, and possibility of getting food poisoning, is lettuce worth it?
In the Netflix documentary “Poisoned,” lettuce is the number one food, along with other bagged salads, likely to lead to food poisoning. According to one report, 614 people fell ill between 2017 and 2022 due to consumption of leafy greens, with 11 people dying. However, reported cases are usually only a small fraction of the actual cases of people that get sick. In fact, leafy greens are responsible for 22% of all cases of foodborne illness
Leafy greens may contain E. coli, norovirus, Salmonella, Listeria, and Cyclospora. There are things you can do to reduce your chances of foodborne disease from lettuce, such as ensuring that it is refrigerated to under 40 degrees, washing your cutting board with hot soapy water and washing the lettuce in fresh water. However, nothing will reduce the risk to zero. Some pathogens get inside the lettuce and cannot be washed off.
Common sources of lettuce contamination include irrigation water (poop from farm animals), wild animal poop and, one of the weird ones, from Mexican farm workers who poop in the fields to get back at owners who beat them (read Fixing Food).
The vast majority of the time that you eat a salad with lettuce, nothing will happen. But why eat it when there are much more nutritious salads without lettuce? Look them up.
How about the nutritional benefits of lettuce? It may help to lose weight, but it’s certainly not helpful for fiber at ½ gram per serving. Carrots have 2 grams per serving. Is it a good source of vitamins compared with other vegetables? Take a look below:
Given all of that information, one way to think about whether lettuce in your salad is worth it is to think about it like drafting a baseball player in the book and movie, Moneyball.
The story is about how the manager of the Oakland A’s, Billy Beane, used something called sabermetrics, introduced by Bill James in his annual Baseball Abstract in 1980. In it, he looked at the benefits, e.g., number of times a player got on base, divided by the annual salary the player costs to get a cost per player for getting on first base. That way, James uncovered the least cost players who were able to hit or walk their way onto first base.
Thinking in those terms, we have the benefits of lettuce (like supplying the % daily need of vitamins) and the costs of lettuce, i.e., the price plus the potential cost of foodborne disease. The expected benefits would also include the value of lettuce as a diet food. If we substitute away from lettuce for more expensive replacements, prices for salads would go up but might not be enough to keep profits the same.
For math geeks, here is the formula for the dollar net value ratio for a food (on a per serving basis):
Lettuce Net Value = (Expected $ Nutritional Benefits – Expected $ Foodborne Disease) / Price of lettuce
With some uncertainty, we could make a rational calculation of the decision to choose lettuce and, in fact, any food. That way, we could rationally choose salad ingredients that maximized the nutrition benefits minus the costs (price plus foodborne disease).
Having done this for lettuce versus other potential salad ingredients, I’m betting lettuce may be a decent deal at home (not bagged salads), but probably not in a restaurant. Maybe we should be thinking more about how we calculate baseball statistics when we choose foods?