"jim" <jimr18@netzero.net> wrote in message
news:1192203305.595281.242670@t8g2000prg.googlegro ups.com...
> I've been following some interesting postings about resveratrol. Has
> anyone seen any guidance about the 'correct' dosages and reliable
> sources of resveratrol pills?
Hi jim,
here are two recent and free review articles.Keep in mind that they seem to
have a connection to Nestle , who makes the supplemented nutrients........
http://www.ajcn.org/cgi/reprint/81/1/230S
Am J Clin Nutr. 2005 Jan;81(1 Suppl):230S-242S. Links
Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97
bioavailability studies.
Manach C, Williamson G, Morand C, Scalbert A, Rémésy C.
Unité des Maladies Métaboliques et Micronutriments, INRA, Saint-Genès
Champanelle, France.
manach@clermont.inra.fr
Polyphenols are abundant micronutrients in our diet, and evidence for their
role in the prevention of degenerative diseases is emerging. Bioavailability
differs greatly from one polyphenol to another, so that the most abundant
polyphenols in our diet are not necessarily those leading to the highest
concentrations of active metabolites in target tissues. Mean values for the
maximal plasma concentration, the time to reach the maximal plasma
concentration, the area under the plasma concentration-time curve, the
elimination half-life, and the relative urinary excretion were calculated
for 18 major polyphenols. We used data from 97 studies that investigated the
kinetics and extent of polyphenol absorption among adults, after ingestion
of a single dose of polyphenol provided as pure compound, plant extract, or
whole food/beverage. The metabolites present in blood, resulting from
digestive and hepatic activity, usually differ from the native compounds.
The nature of the known metabolites is described when data are available.
The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L
with an intake of 50 mg aglycone equivalents, and the relative urinary
excretion ranged from 0.3% to 43% of the ingested dose, depending on the
polyphenol. Gallic acid and isoflavones are the most well-absorbed
polyphenols, followed by catechins, flavanones, and quercetin glucosides,
but with different kinetics. The least well-absorbed polyphenols are the
proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data
are still too limited for assessment of hydroxycinnamic acids and other
polyphenols. These data may be useful for the design and interpretation of
intervention studies investigating the health effects of polyphenols.
PMID: 15640486
http://www.ajcn.org/cgi/reprint/81/1/243S
Am J Clin Nutr. 2005 Jan;81(1 Suppl):243S-255S. Links
Bioavailability and bioefficacy of polyphenols in humans. II. Review of 93
intervention studies.
Williamson G, Manach C.
Nutrient Bioavailability Group, Nestlé Research Center, Lausanne,
Switzerland.
gary.williamson@rdls.nestle.com
For some classes of dietary polyphenols, there are now sufficient
intervention studies to indicate the type and magnitude of effects among
humans in vivo, on the basis of short-term changes in biomarkers.
Isoflavones (genistein and daidzein, found in soy) have significant effects
on bone health among postmenopausal women, together with some weak hormonal
effects. Monomeric catechins (found at especially high concentrations in
tea) have effects on plasma antioxidant biomarkers and energy metabolism.
Procyanidins (oligomeric catechins found at high concentrations in red wine,
grapes, cocoa, cranberries, apples, and some supplements such as Pycnogenol)
have pronounced effects on the vascular system, including but not limited to
plasma antioxidant activity. Quercetin (the main representative of the
flavonol class, found at high concentrations in onions, apples, red wine,
broccoli, tea, and Ginkgo biloba) influences some carcinogenesis markers and
has small effects on plasma antioxidant biomarkers in vivo, although some
studies failed to find this effect. Compared with the effects of polyphenols
in vitro, the effects in vivo, although significant, are more limited. The
reasons for this are 1) lack of validated in vivo biomarkers, especially in
the area of carcinogenesis; 2) lack of long-term studies; and 3) lack of
understanding or consideration of bioavailability in the in vitro studies,
which are subsequently used for the design of in vivo experiments. It is
time to rethink the design of in vitro and in vivo studies, so that these
issues are carefully considered. The length of human intervention studies
should be increased, to more closely reflect the long-term dietary
consumption of polyphenols.
PMID: 15640487
hth
Gys
Resveratrol...Dosage... 
Linear Mode
