How does an apple a day keep the doctor away? Let’s break down this old adage to find out why it is literally and metaphorically applicable to nutrition as medicine. It was Hippocrates — regarded as the father of modern medicine and whose Hippocratic Oath is attributed with defining ethics in modern medical practice — who was quoted as saying “let food be thy medicine.” Unfortunately, modern medical practice, especially in western society, has little to do with nutrition per se. Medical doctors receive very limited training on nutrition and are rather largely trained to treat the symptoms or causes of diseases with pharmaceuticals. Consider “keeping the doctor away” to be a way of saying to prevent or reverse disease progression by one’s own means. If you prevent disease through nutrition (food), you preempt the need to see the doctor.
So the next question here would logically be “can you prevent or reverse disease progression with nutrition?” The answer is yes. You can prevent and even reverse disease progression with the foods you eat. To learn more about why the answer is yes, you can reference our other articles on nutrition as well as those of the authors listed in our suggested reading page. Avoiding processed foods and eating a variety of healthy fruits, vegetables, and meats can prevent and reverse disease progression.
Next, we examine whether apples, specifically, can be good for you as part of a diet that would prevent or reverse disease progression, thus “keeping the doctor away” so to speak. Apples are full of phytonutrients (vitamins and minerals), are free of fat, sodium, and cholesterol, and rank low on the glycemic index (they don’t spike your blood sugar). Specifically, a medium apple contains about 100 calories, around 15% of the fiber and Vitamin C of recommended daily values, as well as small amounts of A and B vitamins, iron, boron, and calcium (which together benefit your skin and protect your bones). Apples contain powerful antioxidants linked to prevention of diseases such as cancer, heart disease, diabetes, and Alzheimer’s. Lastly, apples (specifically the skin of the apples) are a great source of Quercetin which is an anti-inflammatory substance that protects brain cells and protects against allergies by reducing histamines. Thus, apples can and really should be part of a balanced diet that prevents disease thereby keeping the doctor away.
So an apple a day really does keep the doctor away. But if your approach to learning about nutrition is searching the internet for things like “does an apple a day really keep the doctor away” or “are apples good or bad for you,” prepare to be confused. In ANY topic on nutrition, you will find proponents of each extreme of an idea (e.g., apples are good for you or apples are bad for you) as well as everywhere in between on the first page of internet search results. If you research a topic a bit further by reading each article more thoroughly, though, you’ll find out that the key to getting the right answers to your health questions is in how you ask the questions. That is, the hundreds of different answers out there on a topic really are all answers to different questions. That is why it is important to be precise in your questions about nutrition. Then, in reading the results of your search, be prepared to disagree with portions of what you find. For example, there are some who say that any sugar is bad for you when, really, it is added or artificial sugars that are bad for you. Sugars from fruits like apples in their whole form are perfectly fine in moderation. In fact, the USDA and AHA recommend adults eat 2-5 servings of fruits per day as part of a balanced diet.
This brings me to the last component of this, moderation. Moderation is the key to why the adage is “an apple a day” and not “10 apples a day.” You should limit your sugars by eating fruits in their whole forms whenever possible. You may have heard the phrase “eat your fruits and juice your vegetables.” If you eat fruits, the sugars will be released into your blood stream in a healthy way. Juicing fruits removes the bulk of the fruits, the fiber, which is needed to help slow the release of sugar into the bloodstream, and it allows a person to drink the equivalent of 5-10 fruits in a very small amount of juice, all at once. When you drink just the sugars and water of the equivalent of 10 fruits all at once, what you get is a “tsunami effect” on your liver — a huge spike in your blood sugar. In the long term, large spikes in blood sugar can lead to diabetes, heart disease, blindness, neuropathy, and liver or kidney failure. Rather, if you are going to juice for health, you should juice mostly leafy green vegetables with small amounts of fruits to flavor the juices (~ one serving of fruit per juice).
And there you have it, in its entirety. An apple a day keeps the doctor away. Why is this true? Break it down. An (one fruit, not 10 all at once) apple (or orange or pear) a day (as part of a balanced diet) keeps the doctor away (preempts the need to see a doctor for treatment of disease).