The secret to gut health may grow on a tree

Back in the 1860s, the Welsh reportedly coined the phrase “an apple a day keeps the doctor away.” Since then, research has shown that Eve’s forbidden fruit can help prevent dementia, cardiovascular disease, diabetes, breast cancer, and obesity.

And now, a new study has found that organic apples contain natural probiotics that nourish your gastrointestinal (GI) microbiome.

As I’ve written before, a healthy microbiome equals a healthy body and brain. Which may have been what the 19th century Welsh folks meant all along.

A closer look at apples’ nutrients

Apples originated on the hillsides in what used to be known as Soviet Central Asia. The area now encompasses several countries like Kazakhstan, Uzbekistan, etc.

Early apples looked more like crabapples than the big, round fruits we’re familiar with today. Which may explain why, after Russian apples migrated to Europe and North America, the fruits were primarily used to make apple cider.

But during the 20th century, as water sources became safer to drink, apples began to be cultivated more for taste than for their ability to be made into cider.

So we need to consider whether the old admonition about a daily apple was more about drinking cider than eating the whole fruit.

Either way, apples (especially their skin) have been shown to be rich in antioxidants, flavonoids, fiber, B and C vitamins, calcium, potassium, and phosphorus—which explains why they lower the risk of so many chronic diseases.

And while a rather tongue-in-cheek 2015 study found that people who ate an apple a day didn’t go to the doctor any less than non-apple eaters, it did reveal that they used fewer prescription medications.1

Which leads me to a new study…

An apple a day doesn’t keep the probiotic bacteria away

Researchers in Austria analyzed how much probiotic bacteria apples contain, and whether the amount varies between organic and conventional varieties.

The researchers measured the bacteria in apple stems, peels, flesh, seeds, and calyx (the bottom of the apple, where the blossom once appeared). They found that a typical apple—organic or conventional—has about the same amount of probiotic bacteria. Most of the bacteria is in the seeds, but even if you toss out the core, you still get about 10 million bacteria.

The difference, though, is that organic apples have a more balanced, diverse, and evenly distributed population of probiotic bacteria than conventionally grown apples.

Of course, I suspect some of this has to do with pesticides. Organically grown apples (like all organic produce) legally can’t be sprayed with pesticides. These chemicals are harmful to plants in many ways—including killing their naturally occurring probiotic bacteria.

In other words, when it comes to good health, it’s what’s on the apple as well as what’s in it.

Researchers also found that organic apples didn’t contain E. coli and other bacteria that are known pathogens, but that conventional apples did. And as an added bonus, they discovered that the probiotic bacteria in organic apples help them taste better.

A label for your microbiome?

Based on their findings, researchers suggested that information about bacteria and microbes be added to food labels.

And I wholeheartedly support this recommendation. It’s consistent with the increasing awareness that foods, spices, nutrients, and botanicals exercise a lot of influence on the body through their effects on the GI microbiome (what I call “biome-availability”).

Researchers also noted that the probiotics on fruits are affected by cooking. Consequently, organic apples and other fruits should be eaten fresh and raw (in contrast to many vegetables, which are better, nutritionally, when cooked).

So when you’re out and about on your daily walk this fall, snag a crisp, organic apple from an overladen tree, or pick up a bushel at your local farmer’s market. After all, it’s just what the doctor ordered for a healthy microbiome.


1“Association Between Apple Consumption and Physician Visits: Appealing the Conventional Wisdom That an Apple a Day Keeps the Doctor Away.” JAMA Intern Med. 2015;175(5):777–783.

2“An Apple a Day: Which Bacteria Do We East With Organic and Conventional Apples?” Front Microbiol. 2019 Jul 24;10:1629.