The polyphenol resveratrol has been shown to have chemopreventive activity against cardiovascular disease and a variety of cancers in model systems. 1
However, it is not clear whether resveratrol reaches the proposed sites of action in vivo after oral ingestion.
A study published in December 2004 examined the absorption, bioavailability, and metabolism of 14C-resveratrol after oral and i.v. doses in six human volunteers. The “absorption of a dietary relevant 25-mg oral dose was at least 70%, with peak plasma levels of resveratrol and metabolites of 491 +/- 90 ng/ml (about 2 microM) and a plasma half-life of 9.2 +/- 0.6 h. However, only trace amounts of unchanged resveratrol (<5 ng/ml) could be detected in plasma. Most of the oral dose was recovered in urine.”
Thus the bioavailability of resveratrol is low because rapid sulfate conjugation by the intestine/liver appears to be the rate-limiting step in resveratrol’s bioavailability. 2
A subsequent study published in June 2007 examined the bioavailability of resveratrol with very large doses of resveratrol given to 10 volunteers. The dose of 2.5 and 5 grams were given orally and the peak plasma levels of resveratrol at the highest dose were 539 +/- 384 ng/mL (2.4 micromol/L, mean +/- SD; n = 10), which occurred 1.5 h post-dose. Urinary excretion of resveratrol and its metabolites was rapid, with 77% of all urinary agent-derived species excreted within 4 h after the lowest dose. 3
The two studies demonstrated a definite challenge with the bioavailability of resveratrol. In fact, the 2007 study concluded that “the results presented here intimate that consumption of high-dose resveratrol might be insufficient to elicit systemic levels commensurate with cancer chemopreventive efficacy.” 4
The solution to the poor bioavailability of resveratrol may be found in the resveratrol precursor, Polydatin.
Polydatin, also known as piceid or Trans-Resveratrol-3-O-Glucoside, is a stilbenoid glucoside of resveratrol.
Polydatin can be found in the bark of Picea sitchensis and is also isolated from Polygonum cuspidatum, the Japanese knotweed (syn. Fallopia japonica). Polydatin is present at a much higher content (2% polydatin) in dried root of Polygonum cuspidatum than in wine and any other sources.
Polydatin is a precursor of resveratrol and is water soluble, whereas resveratrol is not water soluble.
Polydatin has a glucose molecule attached to the resveratrol molecule. Once polydatin enters the bloodstream the glucose molecule is cleaved off, leaving resveratrol.
Polydatin is converted into resveratrol during the first pass metabolism. This means that while normal resveratrol is destroyed during first pass metabolism, the same metabolism action is converting Polydatin to Trans-Resveratrol and allowing it to stay much longer in plasma. The estimated range provides a bioavailability duration between 2 to 5 times longer than regular resveratrol products. 5
Since Polydatin is hydrolyzed into trans-resveratrol in the small intestine, the half life of resveratrol is longer in blood plasma and tissues. 6
It has been determined that the amount of resveratrol in plasma when consuming Polydatin is 3 times that of taking resveratrol.
The half life of Polydatin can be 4 to 5 times longer than resveratrol when taking the same milligram per kilogram amount.
Print This Post