Does an Apple a Day Really Keep the Doctor Away?

Find out how apples could improve your heart health, help fight cancer and even positively impact your gut.

We’ve all heard the old adage, “An apple a day keeps the doctor away”. The aphorism dates back to 1866 and originally appeared in a Welsh publication as “Eat an apple on going to bed and you’ll keep the doctor from earning his bread.” As it turns out, it is pretty spot on.

It doesn’t matter how you consume an apple or if you are shining one up to give to your teacher — the health benefits are the same. Let’s look further and dissect what is inside an apple.

According to the US Department of Agriculture, depending on the size and variety, one apple with the skin on contains about:

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  • 100 calories
  • 14% of your dietary reference intake (DRI) of vitamin C
  • 2% of your DRI for vitamin A
  • 2% of your DRI for calcium
  • 2% of your DRI for iron
  • A whopping 4 grams of fiber, accounting for almost 20% of your DRI
  • 18 grams of sugar
  • No fat or sodium

We figured out there are calories and some vitamins that are inside apples. But how does that translate to benefits to your health?

A wide range of studies have been conducted to explore the many potential health benefits of apples:

1. Improved heart health

Fiber, which apples have an abundance of, are shown to reduce the risk of heart disease in both men and women. Researchers found that the risk of developing heart disease may decrease by 14% for every 10 grams of fiber eaten daily, and the risk of dying from heart disease may decrease by more than a quarter. Also, it may be time to change up your morning routine as fiber from fruit may be even more beneficial than fiber in cereal. This change in itself could potentially lower the risk of dying from heart disease by 30%.

“Apples are rich in fiber, which can be beneficial for patients with heart disease and high cholesterol,” said Kurt Hong, MD, associate professor of clinical medicine at Keck School of Medicine of USC and a primary care physician at Keck Medicine of USC. “However, with high content of soluble fiber pectin (which can also be found in grapefruits and apricots), overconsumption of apples in some patients can trigger loose stool or diarrhea.”

2. Lower cholesterol

Have you been told that you have high cholesterol? Or do you know someone who does? An Ohio State University study of healthy, middle-aged adults found that eating one apple a day for four weeks lowered blood levels of oxidized LDL (low-density lipoprotein, aka the “bad” cholesterol) by 40%.

3. Protection for brain health

Alzheimer’s can be quite scary and heartbreaking for families. Researchers have found mice that were genetically programmed to develop Alzheimer’s have retained their cognitive skills when given fisetin (the flavonol found in apples and other fruits) supplements. Could this be a preventative measure that could combat Alzheimer’s? It’s too early to tell, but it doesn’t hurt to take action, right?

4. Protection against some cancers

Chances are you know someone who has had cancer. Researchers are working tirelessly to combat the disease. Luckily, small advances could hold big promise for the future of your health. Various studies have found that apples may help reduce breast, prostate, pancreatic, colon, liver and bowel cancer risk. Could the apple be the missing component that helps you add extra years to your life?

“It is a wonderful fruit with high amounts of vitamins, flavanoids and antioxidants,” Dr. Hong said.

5. Improved gut bacteria

Some people always seem to reach for green apples over red and they could be on to something. Did you know that Granny Smith apples contain a large amount of non-digestible compounds, including dietary fiber and polyphenols, which remain intact even as they’re digested? After they reach your colon, these compounds are fermented, which helps promote the growth of healthy bacteria in your gut. Food Chemistry found this aids with digestion and reduces inflammation. This might be a great solution for your acid reflux.

Ready to start crunching away? The USDA recommends storing apples in the fridge to keep them crisp and fresh. They should stay good for about up to three weeks.

Do you want recommendations on what you should be eating? A primary care physician can help you create your weekly meal plans for optimal health, or consider meeting with a digestive expert to discuss a personalized plan.

The USC Digestive Health Center has some of the world’s top digestive specialists. If you are in the Los Angeles area, be sure to schedule an appointment by calling (800) USC-CARE (800-872-2273) or by visiting

By Anne Fritz