Fast Take: Are you frying your health with french fries?

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Each time a nutrition study descends upon the internet I cringe internally. I have to brace myself as I click through the various news outlets covering it, knowing that I may encounter sensational reporting, regardless of the actual content of the scientific study.  Here’s what you need to know about a new study that found an association between fried potatoes and increased mortality.

Background on the study:

The study by Veronese et al., 2017 was a prospective cohort study that followed 4,400 participants aged 45-79 years old from four countries (England, Italy, Spain, and the United States), who either had knee osteoarthritis or were deemed at risk for knee osteoarthritis.  According to the NIH database, the main purpose of the study was to “…better understand how to prevent and treat knee OA [osteoarthritis]”. I know, you are probably thinking, what does this have to do with french fries? The researchers also collected food intake data using a food frequency questionnaire, which indirectly allowed them to study various outcomes like mortality in relation to fried potato consumption.

What the study found:

  • Participants who reported consuming fried potatoes 2-3+ times per week were found to have a 2x higher risk of mortality when compared with the lowest consumers of fried potatoes (<1x per month), after adjustment for a variety of factors.
  • There was NO association between general potato consumption and mortality.

But before you swear off fries forever, there are some things you should know:

Like every scientific study, it is important to consider the methodology and generalizability of the results before letting our imagination run away with the facts (or fiction). The study had a large sample size and did a decent job adjusting for many factors that also could have contributed to increased mortality (such as BMI, physical activity and total energy intake).

However, the study did not adjust for the more nuanced aspects of diet, such as total saturated fat intake, total sodium intake or overall dietary pattern, any of which could have  contributed to the increased mortality. In addition, the main limitation of this study lies in its design. As an observational study, the fact that an association was found between fried potatoes and mortality is not sufficient to prove that fried potatoes cause an increase in mortality.  This can only be done in randomized controlled trials, a type of study that manipulates a variable in a controlled setting, such as potato intake, and then observes the impact. The present study relied on self-reported intake data and did not in any way manipulate the diets of the participants.

Another significant limitation is when you consider how these findings apply to the general population. The data used in this observational study were participants enrolled in the Osteoarthritis Initiative cohort, a group of older individuals with knee osteoarthritis or osteoarthritis risk factors. Since this is a pretty specific group, these findings are not applicable to the general public. Finally, to be included in this cohort, you had to have knee injury or pain, meaning that there could have been additional co-factors influencing these findings.  

Bottom Fry-Line:

Even if the study’s methods were perfect, the data wouldn’t tell us anything we didn’t already know.  Potatoes themselves are a healthy food staple providing long lasting energy and containing key nutrients such as vitamin C, potassium and fiber.  Fried potatoes, by virtue of being fried, are less healthy than potatoes prepared other ways and should be consumed in moderation.  Ahhh moderation, if I only had a french fry for every time I repeated that message.

This blog was written by Christina LiPuma, dietetic intern at Brigham & Women’s Hospital.