An apple a day keeps the doctor away

"Eat to Live, Not Live to Eat"
John H Weisburger, 2000

We’ve all heard the saying that an apple a day keeps the doctor away, probably beginning way back when you were a youngster and your parents were trying to get you to eat some fresh food. Is there any truth in it?

A recent study in the 30th March 2015 edition of the Journal of the American Medical Association attempted to address the question by conducting a cross-sectional study of a nationally representative sample of the noninstitutionalized US adult population.  A total of 8728 adults 18 years and older from the 2007-2008 and 2009-2010 National Health and Nutrition Examination Survey completed a 24-hour dietary recall questionnaire and reported that the quantity of food they ate was reflective of their usual daily diet.  Daily apple eaters were taken as those who consumed the equivalent of at least one small apple (about 150g) daily.  The primary outcome measure was success at "keeping the doctor away," measured as no more than one visit to a physician during the past year.  Secondary outcomes included successful avoidance of other health care services, ie no overnight hospital stays, visits to a mental health professional, or prescription medications. Of 8399 eligible study participants who completed the questionnaire, there were 753 apple eaters (9.0%) and 7646 non-apple eaters (91.0%). Without considering any other contributing factors, the apple eaters were more likely to keep the doctor (and prescription medications) away, but after adjusting for socio-demographic and health-related characteristics, this association was no longer seen. There were also no differences between the two groups in overnight hospital stay or mental health visits, but the apple eaters were marginally more successful at avoiding prescription medications. The authors concluded their data did not support the  'apple a day keeps the doctor away' belief, but did note that the small fraction of US apple eaters appear to use fewer prescription medications.

Questionnaire studies are always subject to the reliability of information gathered.  In this case, how well does a 24-hour snap-shot represent what someone consumes on a yearly basis, and do participants report or remember accurately.  Nevertheless, such information is still better than the unfounded cultural beliefs of the past. The small proportion of US adults who regularly eat apples is interesting, but this ties in with another 2015 study where it was found that more than 60% of the daily calorie intake in US households came from processed foods.  If taken literally, the advice regarding apples would be expected to produce a negative result in any properly conducted study, as no single food, no matter how favoured, could hope to provide all the necessary nutritional components to ensure long-term well-being.  If, however, it is more loosely interpreted to simply mean 'eat more fruit and vegetables', then it's excellent.