Apple consumption tracked through short-term urine markers in people
What it found
Eating apples raised levels of certain plant compounds in urine for about 12 hours in 30 people.
The amount found could tell apart small and large apple portions.
What they found
Studies in people
Phloretin tracks apple intake
A compound called phloretin rose quickly in urine after people ate apples. It peaked around three hours later and was mostly gone within 12 hours. Higher amounts clearly showed when someone ate four apples instead of one or two.
Other markers also rose
Two other plant compounds, epicatechin and procyanidin B2, also increased in urine after apple eating. Like phloretin, they helped separate those who ate four apples from those who ate fewer.
Quercetin not useful here
Another compound sometimes linked to apples, quercetin, barely appeared in the urine samples. The authors note onions provide much more quercetin than apples do, making it a poor marker for apple eating.
Markers fade by morning
By the morning after eating apples, the extra compounds had dropped back to normal levels. This means a single urine test only shows apple eating from roughly the past day.
What the authors conclude
- They conclude that phloretin, epicatechin, and procyanidin B2 work as short-term markers for apple eating in people.
- They suggest collecting urine samples over one to three months to get a better picture of long-term apple intake, since the markers disappear within a day.
- The authors say these markers will not replace food questionnaires yet, but can help check if those records are accurate.
How it was done
Scientists usually rely on food diaries to track what people eat, but these are often inaccurate. They wanted to find objective markers in urine that reliably show how many apples someone ate.
Thirty healthy adults avoided apples for two days, then ate a portion equal to one, two, or four apples. They gave urine samples before eating and over the following days so researchers could measure specific plant compounds.
What it can’t tell you
- This trial only followed people for a few days, so it cannot show what happens with regular apple eating over months or years.
- Because the study measured markers rather than health outcomes, it cannot show whether eating apples changes disease risk.
Who paid
- Authors work at
- Westfälische Wilhelms-Universität Münster, Germany
The paper
- Title
- Short-term biomarkers of apple consumption
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Saenger T, Hübner F, Humpf HU (2017). Short-term biomarkers of apple consumption. Molecular nutrition & food research. doi:10.1002/mnfr.201600629Free full textPubMed 27794196DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error