"An apple a day keeps the doctor away."
This saying is over 150 years old. It originates from Wales, was first printed in 1866, and has since spread to all languages of the world. And it's true — but with a crucial caveat.
It's true for the right apple.
Not for the uniformly red, highly polished specimens on supermarket shelves that smell of nothing and taste of nothing. Not for the apple that has been sprayed thirty times before it landed in your shopping cart. And not for the apple from a high-yield variety bred for size, color, and shelf life — but not for polyphenols.
This article tells the story behind the saying. What truly lies within the apple. What decades of breeding have done to it. And why the path back to the real apple is shorter than you think.
What truly lies within the apple
The apple is a remarkably complex nutrient package. Not because of a single super-substance — but due to the interplay of many substances that work together.
Pectin — the underestimated star. 4 to 5 grams of fiber per medium-sized apple — primarily pectin in the skin and flesh. Pectin is the multi-talent among fibers. It acts as a prebiotic — nourishing beneficial gut bacteria like bifidobacteria and lactobacilli. It regulates blood sugar by slowing down sugar absorption. It lowers cholesterol by binding bile acids. And it binds toxins in the gut.
For diarrhea, grated apple helps because pectin binds fluid in the gut. For constipation, the combination of soluble and insoluble fibers stimulates bowel activity. The apple is one of the few foods that helps with both digestive problems simultaneously.
Polyphenols — the invisible treasures. The most well-known polyphenols in apples are quercetin, catechin, epicatechin, chlorogenic acid, and phloridzin. These substances have antioxidant and anti-inflammatory effects. Quercetin protects cells from oxidative stress and is also a beacon of hope in dementia research — it protects brain cells and can reduce the formation of beta-amyloid, which accumulates as plaque in the brain.
A study by Oxford University concluded that heart attacks and strokes could be significantly reduced if everyone ate an apple daily. A Dutch study confirms this, at least for the risk of stroke.
Phloridzin — a polyphenol almost exclusively found in apples — also appears to protect against bone density loss and can make an important contribution to osteoporosis prevention.
Potassium for heart function and blood pressure. Vitamin C for immune protection. Lutein and zeaxanthin for eye health. Vitamin B6 for the nervous system. And all this at just 55 kilocalories per 100 grams.
And then there are the red-fleshed apples. Varieties like Redlove or Kissabel also contain anthocyanins — the same plant pigments we know from red onions and strawberries. They give the apple its red flesh and bring an additional layer of antioxidant power.
The uncomfortable truth about modern apple varieties
Here lies the core of the problem. And it's directly related to what science knows about polyphenols.
Apples, especially old varieties like Berlepsch, Boskoop, Cox-Orange, and Idared, contain nutrients in a very favorable composition — including many polyphenols. However, from certain apple varieties like Golden Delicious, Gala, or Jonagold, polyphenols have been "bred out." This explains why newer varieties often cause stronger allergic reactions.
This is one of the most significant statements the Federal Center for Nutrition has ever made about apples. Polyphenols are bred out. Not intentionally — but as a side effect of optimizing for size, color, uniform appearance, and shelf life.
Because polyphenols are protective compounds. The plant forms them to protect itself — against pests, UV radiation, fungal pathogens. The stronger the plant and the more it is left to its own devices, the more polyphenols it forms.
A high-yield variety that is sprayed, fertilized, and pampered does not need to form these protective compounds itself — it receives protection from outside. The result: more beautiful, larger, longer lasting — but poorer in precisely the substances that make the apple so valuable.
Moreover, the composition of active substances varies greatly depending on the variety — and it also changes during the ripening process. Unripe fruits provide different plant compounds than fully ripe ones. An apple that is harvested unripe and lands on the shelf after weeks of transport never develops its full polyphenol profile.
The pesticide truth — what hardly anyone says
Apples are sprayed dozens of times before harvest — this is standard practice in South Tyrol and many other fruit-growing regions. And this doesn't just concern conventional farms.
Organic fruit growers use copper, sulfur, and potassium bicarbonate against scab. Unlike synthetic fungicides that penetrate the plant, these active ingredients remain on the surface. However, they are washed off by rain — and organic fruit growers must regularly treat their trees to protect them from fungi.
Copper accumulates in the soil and is toxic to soil organisms. Global 2000 emphasizes that it advocates for a reduction in the use of copper in apple cultivation.
This is the uncomfortable truth: even organic apples cannot do without spraying. Because apple scab — one of the most common apple tree diseases worldwide and the main pathogen in apple cultivation in Austria — comes with the weather and is hardly controllable without protection.
But there is a way to significantly reduce the need for pesticides. And it leads — as always — through the vitality of the plant.
Why vital apple trees protect themselves better
Apple scab — Venturia inaequalis — preferentially attacks stressed trees. A tree that is well supplied with minerals, has an active soil microbiome, and possesses strong cell walls and well-regulated stomata — this tree is more resilient.
Our European field studies with mineral foliar fertilizers based on calcite confirmed this: For apple trees regularly treated with activated calcite, the use of protective agents could be reduced by up to 50 percent in some cases. The fruits became more uniform, ripened earlier, and had a higher dry matter content — which directly means: more polyphenols, more taste, better shelf life.
And the harvest became — year after year — more consistent. No more alternance — the phenomenon where apple trees bear fruit abundantly one year and hardly any the next. A vital plant with optimal calcium and CO₂ supply overcomes alternance because it expends the energy for a full harvest every year.
Eat the peel — the most important single rule when eating apples
Here lies the biggest and simplest upgrade you can make when eating apples.
Most of the polyphenols — quercetin, chlorogenic acid, catechins — are in the peel and in the outer layers of the flesh. Those who peel apples lose a significant portion of these substances.
This, of course, only applies to apples that are uncontaminated — from your own tree, from the farmer's market, from trusted cultivation. Eating a conventionally sprayed apple with the peel is less advisable.
This is another argument for having your own tree — or at least for local contact with a fruit farmer you trust.
Cloudy juice instead of clear — and why that matters
Apple juice is not all the same.
Almost all fiber is lost during pressing — the pectin remains in the pomace. The sugar is concentrated. Blood sugar rises faster. The apple's satiety effect is missing.
Naturally cloudy apple juice is significantly better — it still contains some of the polyphenols and turbid substances. Clear apple juice is essentially concentrated fruit sugar.
Apples and naturally cloudy juice are a kind of protective elixir for the liver — it is probably the oligomeric procyanidins that exert a protective effect and can protect against liver-toxic substances.
Naturally cloudy, preferably from your own pressed apple. The rest is sugar with apple flavor.
The Brix value of apples
According to the Reams reference chart:
Poor: 6 °Brix — the typical supermarket apple
Average: 10 °Brix
Good: 14 °Brix
Excellent: 18 °Brix
An apple with 14 °Brix and an indistinct separation line in the refractometer — that is an apple with a high calcium content, many polyphenols, and true flavor. An apple with 6 °Brix is an apple that has not done its job — neither in the soil nor on the tree.
And the great thing: You can smell the difference. An apple that is truly ripe and contains many secondary plant compounds smells intensely — fruity, complex, unmistakable. An apple with 6 °Brix smells of nothing.
Which varieties are the best?
Old varieties are generally richer in polyphenols than modern high-performance varieties. The Federal Center for Nutrition names Berlepsch, Boskoop, Cox-Orange, and Idared as particularly nutrient-rich varieties.
Particularly recommended for Austria: Styrian Maschansker, Kronprinz Rudolf, Schafnase, Wintergold — old local varieties that have been cultivated for decades in Styria and Lower Austria and have a complex polyphenol profile that is far superior to modern varieties.
And for those who want adventure: red-fleshed apples like Redlove or Kissabel — they also bring anthocyanins and look beautiful.
The connection that ties everything together
Quercetin in the apple — the same quercetin as in the red onion. Anthocyanins in the red-fleshed apple — the same anthocyanins as in the strawberry. Pectin as a prebiotic — the gut microbiome that makes all other nutrients available in the first place.
The apple is not a random product of nature. It is the result of millennia of co-evolution between tree and animal — a plant that makes its fruits so nutrient-rich that animals and humans eat them, spread the seeds, and keep the cycle alive.
This cycle still works. It just needs the right soil, the right tree — and someone who believes that an apple can be more than a uniformly red ball on a supermarket shelf.
An apple a day keeps the doctor away.
The saying is true. For the right apple.
How to care for an apple tree so that it needs less spraying, forms more polyphenols, and reaches a measurable Brix value of 14 °Brix or more — we will show this in the next blog post.
What quercetin, anthocyanins, and pectin have to do with the Brix value — and how to measure nutrient density — in the Brix article with instructions and Reams chart.
Why food today has fewer nutrients than before — in the article about minerals and degraded soils.
We also know quercetin from red onions — what else is in them — in the article about red onions as a superfood.
Sources: Federal Center for Nutrition BZfE, Apples Health and Environment | Vitalis Gesundheitsstudio, Alleskönner Apfel 2025 | myBioma, Apples and Gut Health 2026 | Zentrum der Gesundheit, Why Apples are So Healthy | supersmart.com, Apple Polyphenols | sparklingrocco.com, Health Benefits of Apples 2024 | Land schafft Leben, Apple Soil Care Plant Protection | Schrot & Korn, Organic Apples Spray Differently 2022 | University of Graz, The Health-Promoting Effects of Apples 2016 | Oxford University, Apple Consumption and Heart Attack | Oekomineral Group / Tribo Technologies, Field Studies Apple and Plantos Verde 2011–2014
