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Bioavailability and Half-life
With only one hydroxyl group per molecule, pterostilbene is able to persist in circulation for a longer time. The slight difference in structure also makes pt erostilbene more lipophilic. Pterostilbene can more readily pass through cell membranes—making it more available to support cellular pathways.
Both resveratrol and pterostilbene are naturally occurring in two forms: cis an d trans. The trans forms are more stable and more abundant in nature. Studi es suggest that for both resveratrol and pterostilbene, the trans forms are su perior to the cis forms in terms of biological activity.
-Bioavailability and Half-life
The good news about resveratrol and pterostilbene is that they’re both readil y absorbed after oral intake, and are even capable of crossing the blood-brai n barrier. The bad news is that they’re rapidly metabolized. Their time in circ ulation is fleeting.
The absorption rate of resveratrol from the intestinal lumen is about 75 perc ent, but its rapid metabolism in the liver results in oral bioavailability of only about 1 percent. That’s because the liver produces resveratrol conjugates—pr imarily glucuronides and sulfates. In a human bioavailability study, 15 healthy volunteers each took a 500 mg capsule of trans-resveratrol. Blood samples tak en after dosing showed that free resveratrol only represented 0.28 percent of total resveratrol in circulation, with the rest consisting of conjugated glucuro nides or sulfates.
The study also showed that resveratrol was short-lived— its concentration pea ked at only about one hour after intake. That result was similar to an earlier study, which found that the half-life of trans-resveratrol was one to three ho urs following a single dose.
When a compound has such low bioavailability and such a short half-life, it’s difficult to maintain a concentration in circulation. One study found that eve n when people took 150 mg of trans-resveratrol six times per day, they still had low plasma concentrations.
One of the most commonly cited comparisons of resveratrol and pterostilbene
