My colleague recently sent along an intriguing and fun research article. We’ve all heard the aphorism: “An apple a day keeps the doctor away.” And while it seems intuitively healthy and practical because fruit and vegetable consumption has innumerable health benefits, this colloquialism, like many, is not rooted in established scientific evidence. Until now. Authors from the Geisel School of Medicine at Dartmouth College decided to quite literally test the effectiveness of apple eating by examining “the relationship between eating an apple a day and keeping the doctor away.” They used National Health and Nutrition Examination Survey (NHANES) data to investigate health care utilization trends in approximately 750 adults who, by their own admission, reported eating an apple a day vs. over 7500 adults who did not. And although this seems fun, and yes, slightly frivilous, it has bigger implications. From the overall NHANES database, authors estimate that “about 19.3 million US adults are apple eaters who consume the equivalent of approximately 26.9 million small apples daily…whereas 207.2 million adults are non–apple eaters (eating less than 1 small apple daily).” If an apple a day really keeps the doctor away, then this inexpensive health habit could be an effective intervention with which to reduce the costs of healthcare utilization!
Authors did find in initial analyses that daily apple eaters were more likely to limit visits to the physician (Figure 1), as apple eaters reported 0-1 visits to the physician in the previous year and non-apple eaters were more likely to report 2 or more visits (association was statistically significant at p = 0.03).
Figure 2 also shows that in addition to avoiding more than 1 yearly physician visit, daily apple eaters were also more likely to avoid using a prescription medication in the last month (again, association was statistically significant at p = 0.01).
However, adults who eat apples daily tend to in general be healthier. They are more highly educated and less likely to smoke. When authors corrected for these and other sociodemographic and health-related characteristics that differed between apple eaters and non-apple eaters, the relationships became less promising. Figure 3, which shows these adjusted relationships, demonstrates that only the association between apple eating and avoidance of prescription medications remained marginally significant after adjustment for other health characteristics.
So, the conclusion? Authors suggested that perhaps we should rename the aphorism to: “An apple a day keeps the pharmacist away,” since evidence does not support that apple consumption markedly reduces physician visits but does demonstrate a small impact on reduction in prescription use. Does the trend between apple use and prescription avoidance mean anything? Well, authors also report that “in a back-of-the-envelope calculation, based on a mean medical prescription cost among US adults of $82.75 in 2010, we estimate the difference in annual prescription medication cost per capita between apple eaters ($1697) and non–apple eaters ($1925) to be $228. If all 234.6 million US adults were apple eaters, and if apples protect against prescription medication use, national prescription costs would be considerably lower (by approximately $47.2 billion). Based on the cost per pound of Red Delicious apples,321 small apple daily for each of the estimated 207.2 million adult non–apple eaters would cost approximately $28.0 billion—a potential net savings of up to $19.2 billion. ” Certainly, this could be important, but there would need to be rigorous evidence from randomized controlled trials that indeed, an intervention as simple as initiating an apple a day resulted in a direct reduction in prescription drug use. Regardless, though, this fun and intriguing paper was a reminder that we should always be asking ourselves whether even the most simple, straightforward and common assumptions about health and disease are grounded in evidence. Too often, they are not, but with our increasingly data-driven society, the answers are often just a few clicks away.