Grape polyphenols, body weight and repeated daily intake in people
What it found
After 10 days of taking grape polyphenols, lean people absorbed more into their blood than overweight people.
Repeated daily doses raised blood levels in lean people but not in overweight people.
What they found
Studies in people
Repeated doses in lean people
In lean people, 10 extra days of grape polyphenols roughly doubled the amount of catechin, epicatechin and quercetin reaching the blood compared to the first day. The rise was 104% for catechin, 89% for epicatechin and 69% for quercetin.
Repeated doses in overweight people
Unlike the lean group, overweight and obese people did not show higher blood levels of these grape compounds after 10 days of daily dosing.
Body size differences after dosing
By day 11, lean people had about twice as much epicatechin and resveratrol in their blood as overweight people. Catechin levels were also about double in lean people, though this difference was just short of being statistically clear.
First dose showed no difference
On the very first day, before any repeated dosing, blood levels of all four measured grape compounds were about the same in lean and overweight people.
What the authors conclude
- They suggest that both body weight and repeated daily intake change how grape polyphenols are taken up or broken down in people.
- The authors note that lean and overweight people might need different advice on how much and how often to eat foods rich in these compounds.
- They say the exact reasons behind these differences remain unclear and call for more research.
How it was done
Overweight people face higher risks for heart disease and diabetes, conditions that plant compounds called polyphenols may help with. Earlier work in animals suggested that taking these compounds repeatedly changes how the body handles them, so the authors wanted to see if this happens in people of different body sizes.
Twelve volunteers took part: 6 lean and 6 overweight or obese. They followed a low-polyphenol diet for 2 days, then took a large dose of resveratrol, grape seed extract and grape juice totaling 2125 mg of polyphenols. Blood was drawn over 6 hours on day 1 and again on day 11 after 10 more days of daily dosing.
What it can’t tell you
- This was a small pilot study with only 12 people, so the results may not apply to everyone.
- The study measured how much of the grape compounds reached the blood, not whether they changed health outcomes like heart disease or blood sugar.
- Scientists do not yet know why lean and overweight people handled the grape polyphenols differently.
Who paid
- Funding
- Funded by NCCIH NIH HHS (from the PubMed record).
- Authors work at
- US Department of Agriculture, USA; Purdue University, USA; Icahn School of Medicine at Mount Sinai, USA
The paper
- Title
- The effect of obesity and repeated exposure on pharmacokinetic response to grape polyphenols in humans
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Novotny JA, Chen TY, Terekhov AI, et al (2017). The effect of obesity and repeated exposure on pharmacokinetic response to grape polyphenols in humans. Molecular nutrition & food research. doi:10.1002/mnfr.201700043Free full textPubMed 28654207DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error