Darryl,
You wrote in another post:
Quoted message said:Doesn't matter which has higher levels of resveratrol since it's
conjugated on absorption. I am unawares of any study that looks at
the benefits, or lack thereof, of these conjugates. ;-)
Did you have this abstract in mind?
Arbi
Clin Biochem. 2003 Feb;36(1):79-87. Related Articles, Links
Absorption of three wine-related polyphenols in three different
matrices by healthy subjects.
Goldberg DM, Yan J, Soleas GJ.
Department of Laboratory Medicine and Pathobiology, University of
Toronto, ON, Canada M5G 1L5. [email hidden]
BACKGROUND: Despite their powerful biologic activities conducive to
protection against atherosclerosis, cancer and inflammatory diseases
demonstrated in vitro, there is considerable doubt whether the
polyphenolic constituents present in red wine and other dietary
components are effective in vivo. OBJECTIVE: We have tested the
absorptive efficiency of three of these constituents
(trans-resveratrol, [+]-catechin and quercetin) when given orally to
healthy human subjects in three different media. DESIGN: Twelve
healthy males aged 25 to 45 were randomly assigned to three different
groups consuming orally one of the following polyphenols:
trans-resveratrol, 25 mg/70 kg; [+]-catechin 25 mg/70 kg; quercetin 10
mg/70 kg. Each polyphenol was randomly administered at 4-week
intervals in three different matrices: white wine (11.5% ethanol),
grape juice, and vegetable juice/homogenate. Blood was collected at
zero time and at four intervals over the first four hours after
consumption; urine was collected at zero time and for the following
24-h. The sums of free and conjugated polyphenols were measured in
blood serum and urine by a gas-chromatographic method. RESULTS: All
three polyphenols were present in serum and urine predominantly as
glucuronide and sulfate conjugates, reaching peak concentrations in
the former around 30-min after consumption. The free polyphenols
accounted for 1.7 to 1.9% (trans-resveratrol), 1.1 to 6.5%
([+]-catechin) and 17.2 to 26.9% (quercetin) of the peak serum
concentrations. The absorption of trans-resveratrol was the most
efficient as judged by peak serum concentration, area-under-the curve
(4 h) and urinary 24-h excretion (16-17% of dose consumed).
[+]-Catechin was the poorest by these criteria (urine 24-h excretion
1.2%-3.0% of dose consumed), with quercetin being intermediate (urine
24-h excretion 2.9%-7.0% of dose consumed). Some significant matrix
effects were observed for the serum polyphenol concentrations, but in
the case of urine no matrix promoted significantly higher excretion
than the other two. CONCLUSIONS: The absorption of these three
polyphenols is broadly equivalent in aqueous and alcoholic matrices
but, at peak concentrations of 10 to 40 nmol/L, is inadequate to
permit circulating concentrations of 5 to 100 micromol/L consistent
with in vitro biologic activity. The voluminous literature reporting
powerful in vitro anticancer and antiinflammatory effects of the free
polyphenols is irrelevant, given that they are absorbed as conjugates.
PMID: 12554065 [PubMed - indexed for MEDLINE]