Cranberry extract, iron and inflammation in rowers
What it found
In 16 rowers, cranberry extract raised antioxidant capacity in the blood but did not change most markers of inflammation or iron.
The authors say it strengthened antioxidant potential after hard exercise.
What they found
Studies in people
Antioxidant capacity
After 6 weeks, the cranberry group had higher total antioxidant capacity at rest, after exercise and after recovery than the placebo group.
Inflammation markers
Cranberry extract did not significantly change levels of IL-6 or TNF-alpha. Exercise raised IL-6 in both groups at both tests.
Hepcidin and myoglobin
After exercise, the placebo group had higher hepcidin and myoglobin, but the cranberry group did not. The authors say cranberry did not directly affect these markers.
Iron and binding capacity
Serum iron, total iron-binding capacity and unbound iron-binding capacity rose after exercise in both groups at the second test. Cranberry did not significantly change these.
Ferritin and transferrin receptor
Neither cranberry nor exercise significantly changed ferritin or soluble transferrin receptor levels.
What the authors conclude
“Supplementation with cranberry extract contributed to a significant strengthening of antioxidant potential in individuals exposed to strenuous physical exercise.”
Also in their conclusions
- They conclude that cranberry extract strengthened antioxidant potential in people doing strenuous exercise.
- They state that supplementation did not exert direct effects on inflammatory markers and indices of iron metabolism (TNF-alpha, hepcidin and myoglobin).
- They call for more research on how cranberry components, especially anthocyanins, affect iron metabolism, and for guidelines on cranberry supplement use.
How it was done
Hard training can cause inflammation and disturb iron handling in the body. The authors wanted to see whether cranberry, which contains antioxidant and iron-binding compounds, could help.
They studied 16 male Polish national rowers during a 6-week training camp. Nine took 1200 mg of cranberry extract daily and seven took a placebo, and all did 2000-m rowing tests at the start and end.
What it can’t tell you
- This was a small study of 16 male rowers, so the results may not apply to other people or to women.
- The study lasted 6 weeks, so it cannot show what happens over longer periods.
Who paid
- Authors work at
- Faculty of Physical Culture in Gorzów Wlkp. Poland, Poland; University School of Physical Education in Poznañ, Poland; University School of Physical Education in Poznań, Poland
The paper
- Title
- Effects of cranberry ( Vaccinum macrocarpon ) supplementation on iron status and inflammatory markers in rowers
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Skarpańska-Stejnborn A, Basta P, Trzeciak J, Michalska A, Kafkas ME, Woitas-Ślubowska D (2017). Effects of cranberry ( Vaccinum macrocarpon ) supplementation on iron status and inflammatory markers in rowers. Journal of the International Society of Sports Nutrition. doi:10.1186/s12970-017-0165-zFree full textPubMed 28261001DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error