Phlorizin Explained Simply

1. What It Is About

Phlorizin is a plant compound. It belongs to a group that experts call dihydrochalcones and is chemically bound to a sugar molecule. It is most commonly found in apples, particularly in the peel, seeds, and leaves. Smaller amounts are also present in other rose family plants such as pears or quinces. For the plant, it acts as a defence against pathogens and helps regulate sugar metabolism. Phlorizin gained attention when researchers discovered that it slows the reabsorption of sugar in the kidneys. In the body, there are proteins that absorb sugar from the intestines and reclaim it in the kidneys. Phlorizin can block these proteins. As a result, less sugar enters the bloodstream, and more sugar is excreted in the urine. This mechanism later inspired the development of medications now used in diabetes treatment. Phlorizin itself is metabolised in the intestines into another compound, phloretin, during which some of its activity is lost.

2. What Studies Show

The most important human study was conducted in 2015 (3). The study was small: six healthy individuals drank a sugar solution. On one occasion, they received a powder made from unripe apples containing high levels of phlorizin; on another, they did not. With the powder, blood sugar levels rose significantly less after drinking the solution, and the body excreted more sugar in the urine over the following hours. This provides a first indication that the mechanism also functions in humans.

A second study, the AppleCOR study from 2023 (2), examined how differently people absorb phlorizin. The participants consumed freeze-dried apple snacks containing varying amounts of phloretin. The results showed that absorption varied greatly between individuals. In most participants, a specific metabolite was primarily detected in the urine. Women more frequently exhibited this pattern than men. Those who absorbed more phloretin tended to have slightly lower blood sugar and insulin levels. This is an indication, but not yet conclusive.

The significance of phlorizin is most clearly evident in the medications developed based on its mechanism. A 2013 review (1) describes how drugs such as canagliflozin, dapagliflozin, and empagliflozin reduce long-term blood sugar levels, decrease body weight, and slightly lower blood pressure in people with diabetes. However, these drugs are not phlorizin itself; they were synthetically designed to enhance efficacy and improve absorption.

Cell and animal studies have yielded additional observations. In these models, phlorizin showed activity against harmful substances and inflammatory mediators. Whether this has relevance for humans has not been studied and remains a hypothesis at present.

3. What Remains Unclear

The key unanswered question is whether phlorizin itself can benefit humans. There are no controlled long-term studies addressing this. The two human studies focused on absorption and metabolites rather than disease progression. Since phlorizin is converted to phloretin in the intestines, which is less active, laboratory findings cannot simply be applied to humans. Additionally, the amount of phlorizin that reaches the body varies widely between individuals, and the reasons for this are under investigation. For cancer and inflammation, observations are currently limited to cell cultures and animal models. How phlorizin interacts with other substances or medications is also an open question. Studies to clarify these points have yet to be conducted.

4. What This Means in Everyday Life

Phlorizin is found in apples, especially in the peel and seeds. However, the human studies did not use ordinary apples but specially prepared powders and snacks with defined phlorizin content. Whether and how much phlorizin is absorbed when eating apples varies greatly from person to person. Some individuals absorb almost none, while others absorb significantly more. Therefore, no consistent effect can be attributed to consuming apples. The mechanism is well described: phlorizin inhibits the proteins responsible for sugar absorption and reabsorption. A treatment based on phlorizin itself has not been established. The question of whether forms with better absorption and measurable effects in humans can be developed remains of interest.

All details with study numbers and sources: detailed page on phlorizin. For children: Phlorizin for children.