We all probably know that French fries aren’t a healthy food choice, but are they killing us? If you’ve kept up on the news in the last week, you probably saw headlines such as “Killer Side Dish: French Fries Linked to Increased Risk of Death” (www.today.com), and my favorite “Attack of the Killer Potatoes” (www.nationalpost.com). While these titles certainly get clicks, is this information accurate? Let’s take a closer look at the study that inspired these “murderous” headlines.
The study involved 4400 people between the ages of 45-79 who had arthritis in their knees, or who were at increased risk of having arthritis in their knees. While French fries have nothing to do with knee pain specifically, the researchers also collected careful diet histories utilizing food frequency questionnaires (FFQ). FFQ’s are used in all kind of nutrition-related research and is essentially a checklist that assesses how often someone eats particular foods over a given period. While they are frequently used (pun intended), they have their limitations. Can you tell me how many times over the last six months that you’ve consumed milk, potatoes, or chicken? These questionnaires are estimates, at best.
The researchers found that those people who reported eating French fries more than 2-3 x a week had twice the risk of death as those who consumed French fries less than 1 x/month. There was no such risk found with eating other forms of potatoes. The study did control for weight, exercise, and general calorie intake (which is good), but did not control for other factors that could have affected a person’s risk of death such as salt and saturated fat intake. Also, this study only looked at a particular group of individuals—middle-aged to older adults who were experiencing knee pain. It’s not possible to generalize these results to everyone.
This study is also limited in that it is an observational study. An observational study can detect correlation only—one thing happens, and another thing happens—it may be cause an effect, coincidence, or they may have absolutely nothing to do with each other.
My favorite example of correlation is one I use in classes I teach. Everyone who has ever gone to the moon has eaten chicken. Does that mean eating chicken makes you go to the moon?
This study doesn’t tell us much that we didn’t already know. Eating large amounts of fried foods of any kind = bad. Potatoes are an excellent staple food with lots of nutrients. If you choose fries, bake them at home, and use spices to season instead of salt. And if you find yourself in the occasional drive-thru, split your fries with a friend or enjoy a small serving.