No blood tests at all in that study. Just in vitro skin sample absorption measurements. And no logic at all to their theory resveratrol might travel from the skin into the blood stream.
Howard
You are absolutely right Howard. Looking at some other studies of how resveratrol reacts with the skin, I found one which may interest you:
http://www.ncbi.nlm....les/PMC3601074/ PLoS One. 2013; 8(3): e59632.
Published online 2013 March 18. doi: 10.1371/journal.pone.0059632
PMCID: PMC3601074
Resveratrol Induces Long-Lasting IL-8 Expression and Peculiar EGFR Activation/Distribution in Human Keratinocytes: Mechanisms and Implications for Skin Administration
They review a number of methods for topical administration, and show some surprising effects on normal keratinocytes, with the effects changing with dose, but also over time.
With regard to possible preventive/clinical feasibility of Resv for skin administration, we observed that Resv at pharmacologically relevant concentration (5–50 µM) caused serious and long lasting deregulation of adaptive reactions to inflammatory (TNFα) and growth (TGFα) stimuli in normal human skin keratinocytes. These Resv-associated effects could bring both beneficial and deleterious outcomes: from one side, they could aim at the enforcement of intrinsic skin cell survival mechanisms (IL-8 over-production, enhanced ERK1/2 and NFκB phosphorylation, and AP-1 transactivation), and from the other side, they could damage sensitive, ageing or ailing skin, thus enhancing the risk of tumorigenesis (EGFR activation, its nuclear retention, and AP-1 transactivation), augmenting inflammatory burden (IL-8 overproduction, enhanced EGFR/ERK and NFκB phosphorylation), and diminishing physiological skin regeneration and wound healing (decreased keratinocyte proliferation), like it has been shown previously
In humans, only a small fraction of the nutritional Resv reaches the body fluids as free Resv, due to its active enterohepatic metabolism [80]. The amount of Resv ingested from dietary sources such as wine and fruit juices (containing not more than 5 mg/ml resveratrol) often results in plasma levels that are either not detectable or several orders of magnitude below the micromolar concentrations that are typically employed in vitro (32 nM–100 µM) [81]. Administration of 25 mg Resv results in plasma concentrations of the free form that range from 1 to 5 ng/ml [82], and administration of higher doses (up to 5 g) increased the plasma Resv concentrations to about 500 ng/ml [83]. Reasonably, the concentrations of free Resv in peripheral tissues such as the epidermis must be much lower, although its lipophilicity could dramatically affect its distribution. In the last years, the possibility to introduce free Resv transcutaneously has been explored. Topical application of Resv as its triphosphate salt derivative resveratrate was shown to protect human skin from damage due to repetitive ultraviolet irradiation significantly better than application of free Resv or an antioxidant preparation used as a control [84]. Resveratrate is a transient derivative of Resv, since free Resv is released at the level of stratum corneum where dephosphorylating enzymes reside. Experiments performed on biopsies of pig skin demonstrated that treatment with resveratrate compared to the parent compound led to a more homogeneous distribution of Resv throughout the stratum corneum and viable epidermis [85]. However, no data on the concentrations reached by Resv or its bioactive metabolites in the epidermis in vivo are available. By using mouse skin, transcutaneous penetration and accumulation of free Resv in the viable epidermis was shown to be highly favoured by the use of acqueous, mildly acidic (pH 6) buffers in the form of topically applied, adherent hydrogels [86]. Finally, the investigation on the possible topical administration of Resv via nonoparticles is presently very active, although technical limitations, such as the use of organic solvents, are still to be overcome
Edited by cudBwrong, 22 February 2014 - 09:02 PM.