Optimizing Metabolism

by Ingrid Kohlstadt, MD, MPH:

High Impact from Fresh Fruits

People would choose foods that prevent cancer if medical science could decide on what those healthful choices are! Eating 5 to 7 fruits and vegetables a day was one of the few solid pieces of nutritional advice for cancer prevention. Yet even that has been called into question. It’s as if scientists are dueling with data rather than innovating ways to help people achieve more healthful diets. This column is an appeal for the practical.

Some of my colleagues claim that they find reliable answers for their patients because they only consider the peer-reviewed published medical literature. Okay, I thought. I’ll conduct a survey of the peer reviewed medical literature around nutrition. Here’s my list:

• Avoid gluten, but don’t leave out fiber and whole grains.
• Lower your dietary fat intake, but be sure to get enough fatty vitamins and omega-3s.
• Get vitamin D, but be careful which kind and don’t get too much sun.
• Identify and stop eating the foods to which you are allergic or intolerant, but focus on your overall diet to make sure it is balanced.
• Eat less but don’t skip meals.
• Avoid table salt, but other salts such as magnesium and potassium are important.
• Milk is an excellent source of calcium, but be sure to avoid caloric beverages
• Vegetarian is healthful as long as you eat enough protein and minerals such as those from lean meats.
• Cook your meat thoroughly to prevent infection, but don’t overcook it, because that forms harmful chemical byproducts.
• Eggs increase cholesterol so avoid or limit them, especially hidden eggs, but eggs are a nourishing protein with fats important for the brain.
• Avoid calorie-dense foods, but nuts have minerals and protein. A handful makes an ideal lunch snack if your child’s school permits them.

Such medical findings are difficult to reconcile even for health professionals. All the recommendations are confusing, and some go so far as being contradictory. Discerning nourishing choices is becoming increasingly difficult.

Unfortunately there’s a new addition to the nutrition contradictions’ list – apple eating. In the December 17, 2013, Christmas edition of the British Medical Journal, researchers validated the centuries-old Welsh saying that an apple a day keeps the doctor away. In the March 30, 2015, April Fools’ Day edition, JAMA internal medicine conducted an analysis arriving at the opposite conclusion about daily apple consumption.

The authors took aim at a folk expression. The whole point of such sayings is to help people make good choices, so unnecessarily calling them into question is a setback for public health. I tried to infuse humor in my Medscape posting in defense of the apple idiom:

Dr. INGRID KOHLSTADT| Preventive Medicine

Apr 1, 2015

There is an important “arm” to this study which has not yet been conducted. An apple a day still keeps the doctor away if you throw hard and have good aim. Happy April 1st.

Then I sent the JAMA editor a letter. Again I tried humor to prod my colleagues towards a closer look at their data. The Davis study found that ethnic and racial minorities were more likely to eat apples. Yet the highly visible article did not take the opportunity to bring attention to the salient public health finding. In my letter I tried to underscore the importance of access.

First I would like to write in the margins of the JAMA editor’s laughter prescription. The study by Davis et al. did not address an important mechanism by which an “apple a day keeps the doctor away,” a mechanism of potentially “high impact.”¹ Specifically, an apple a day keeps the doctor away especially for those who throw hard and aim.² The authors may wish to modify their conclusion “Evidence does not support that [consumption of] an apple a day keeps the doctor away.” Alternatively the study design could include a “throwing arm.”

Unfortunately injuries from fruit consumption are not limited to Newton’s apple. Prevention is often possible as evidenced by the absence of coconuts in palm trees lining tropical resorts. However the absence of fruit-laden trees can lead to food insecurity. Fruit gathering was a significant cause of injuries in one database, especially among minority and lower income families not privileged to the low-hanging fruits.^3,4

Davis et al. found that apple eaters were more likely to be of a racial or ethnic minority despite the 19th-century English origin of the apple-a-day idiom. Improving safe access may further consumption of apple, pineapple, pear-apple (Asian pear), love apple (tomato), custard apple (cherimoya) and other 21st-century apples. When fresh fruits aren’t available people consume processed fruits with added sugar instead.^4,5 While data about apple consumption may be inconclusive, reducing sugar consumption unquestionably reduces physician visits.

Let’s stick with the folk sayings that we have and make it possible for people to use them. In my opinion if we “take aim” at the shortage of unsweetened fruits we are likely to have a “high impact” on cancer prevention.

Notes

1. Davis MA, Bynum JP, Sirovich BE. Association between apple consumption and physician visits: appealing the conventional wisdom that an apple a day keeps the doctor away.JAMA Intern Med. 2015.

2. Lawson BR, Comstock RD, Smith GA. Baseball-related injuries to children treated in hospital emergency departments in the United States, 1994-2006.Pediatrics. 2009;123(6):e1028–e1034.

3. Negin J et al. Barking up the wrong tree: injuries due to falls from trees in Solomon Islands.Med J Aust. 2014;201(11):698–700.

4. Vazquez MG. Latin American immigrant youth search for fresh papaya in the US, in NutriBeeNational Nutrition Competition. In: Kohlstadt I, ed. 2015.

5. DeChristopher LR, Uribarri J, Tucker KL. Intakes of apple juice, fruit drinks and soda are associated with prevalent asthma in US children aged 2-9 years.Public Health Nutr. 2015:1–8.