Apple polyphenols, blood sugar and uric acid in overweight people
What it found
Taking 300 mg of apple polyphenols daily for 8 weeks lowered fasting blood sugar by 10.3% and uric acid by 14.0% in overweight people.
It also improved how well their blood vessels responded.
What they found
Studies in people
Blood sugar levels
After 4 weeks, fasting blood sugar dropped by 6.1% in the group taking the apple extract. By 8 weeks, it had fallen by 10.3% compared to their starting point and to the dummy pill group.
Blood vessel response
The apple extract group showed better blood vessel reactivity after 8 weeks compared to both their own starting point and the dummy pill group. People whose uric acid dropped the most saw the biggest improvement in their blood vessels.
Other health markers
Cholesterol, triglycerides, liver enzymes, kidney markers, blood pressure and body weight stayed about the same in both groups over the 8 weeks.
Animal and lab studies
Lab cell tests
Tests on living human blood vessel cells showed the apple extract blocked the uric acid enzyme at very small amounts, working in a similar way to a standard drug used for this purpose.
Studies in people and animals
Uric acid levels
In the lab tests, the apple extract blocked the enzyme that makes uric acid. In the people taking the extract for 8 weeks, uric acid levels fell by 14.0%.
What the authors conclude
- They conclude that apple polyphenols act as strong blockers of the uric acid enzyme in lab tests and mildly lower uric acid in people.
- They suggest these extracts could be added to diet and lifestyle changes for people with slightly high uric acid and blood sugar.
- They say larger trials are needed to confirm whether apple polyphenols can help manage metabolic syndrome.
How it was done
High uric acid is linked to heart disease risk, and apple compounds might help lower it. The authors wanted to see if an apple extract could reduce uric acid and improve blood vessel function in overweight people with slightly high blood sugar.
They tested the extract on human cells in a lab to see if it blocked the enzyme that makes uric acid. They then ran a trial where 62 overweight adults took either 300 mg of apple polyphenols or a dummy pill every day for 8 weeks. Fifty-three people finished the study.
What it can’t tell you
- The trial lasted only 8 weeks, so scientists do not yet know if these effects last longer or if the body adapts over time.
- The volunteers were overweight with slightly high blood sugar, so the results may not apply to everyone.
- The study did not include people with diagnosed high uric acid disease.
Who paid
- Authors work at
- Alma Mater Studiorum University of Bologna, Italy; University of Bologna, Italy
The paper
- Title
- Effect of apple polyphenols on vascular oxidative stress and endothelium function: a translational study
- Type
- Randomised controlled trial
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Cicero AFG, Caliceti C, Fogacci F, et al (2017). Effect of apple polyphenols on vascular oxidative stress and endothelium function: a translational study. Molecular nutrition & food research. doi:10.1002/mnfr.201700373Free full textPubMed 28755406DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error