"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 one 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 basket. And not for the apple from a high-performance variety bred for size, color, and shelf life – but not for polyphenols.
This article tells the story behind the saying. What really makes an apple. What decades of breeding have done to it. And why the path back to the real apple is shorter than you think.
What's really in an apple
The apple is a remarkably complex nutrient package. Not because of a single super-substance – but because of the interplay of many substances that work together.
Pectin – the underestimated star. 4 to 5 grams of fiber per medium-sized apple – mainly pectin in the skin and pulp. 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 levels by binding bile acids. And it binds pollutants in the gut.
Grated apple helps with diarrhea 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 help with both digestive problems simultaneously.
Polyphenols – the invisible treasures. The best-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 one apple daily. A Dutch study confirms this, at least for the risk of stroke.
Phloridzin – a polyphenol found almost exclusively 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 as 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 add an extra layer of antioxidant power.
The uncomfortable truth about modern apple varieties
Here lies the core of the problem. And it has direct relevance to what science knows about polyphenols.
Apples, especially old apple varieties such as Berlepsch, Boskoop, Cox Orange, and Idared, contain nutrients in a very favorable composition – including many polyphenols. From certain apple varieties such as Golden Delicious, Gala or Jonagold, on the other hand, polyphenols have been "bred out." This explains why newer varieties often trigger 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-performance variety that is sprayed, fertilized, and pampered does not need to produce 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.
Furthermore, the composition of the 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 truth about pesticides – what almost no one says
Apples are sprayed dozens of times before harvest – this is the norm in South Tyrol and many other fruit-growing regions. And this doesn't just concern conventional farms.
Organic fruit farmers 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 the organic fruit farmer has to treat his trees regularly 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 pest 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, that has an active soil microbiome, that has strong cell walls and well-regulated stomata – this tree is more resistant.
Our European field studies with calcite-based mineral foliar fertilizers confirmed this: for apple trees that were 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 flavor, better shelf life.
And the harvest became – year after year – more uniform. No more alternation – 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 alternation because it expends the energy for a full harvest every year.
Eat the peel – the most important single rule when eating an apple
Here lies the biggest and easiest upgrade you can make when eating an apple.
The majority of polyphenols – quercetin, chlorogenic acid, catechins – are found in the peel and in the outer layers of the fruit flesh. Those who peel apples lose a significant portion of these substances.
Of course, this 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 regional contact with a farmer you trust.
Cloudy juice instead of clear – and why that matters
Apple juice is not just apple juice.
When pressed, almost all fiber is lost – the pectin remains in the pomace. The sugar is concentrated. Blood sugar rises faster. The satiating effect of the apple 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 hepatotoxic substances.
So if you drink apple juice – make it naturally cloudy, preferably from your own pressed apples. The rest is sugar with apple flavor.
The Brix value of an apple
According to the Reams reference table:
Poor: 6 °Brix — the typical supermarket apple Average: 10 °Brix Good: 14 °Brix Excellent: 18 °Brix
An apple with 14 °Brix and an indistinct dividing line in the refractometer – that's an apple with high calcium content, many polyphenols, and real flavor. An apple with 6 °Brix is an apple that hasn't done its job – neither in the soil nor on the tree.
And the great thing is: 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 regional varieties that have been cultivated for decades in Styria and Lower Austria and have a complex polyphenol profile 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 binds everything
Quercetin in apples – the same quercetin as in red onions. Anthocyanins in red-fleshed apples – the same anthocyanins as in strawberries. 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, produces more polyphenols, and achieves a measurable Brix value of 14 °Brix and more – we'll show you 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 table.
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 it – in the article about red onions as a superfood.
Sources: Federal Center for Nutrition BZfE, Apples Health and Environment | Vitalis Health Studio, All-rounder Apple 2025 | myBioma, Apples and Gut Health 2026 | Center for Health, 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
