Short answer: In rats, pterostilbene was about 80% bioavailable versus about 20% for resveratrol.1 In people, only trace unchanged resveratrol reaches the blood.2 Human outcome data differ: resveratrol lowered HbA1c in a meta-analysis, while the main pterostilbene trial lowered blood pressure but raised LDL by about 17 mg/dL.34 No human trial compared them.
| Resveratrol | Pterostilbene | |
|---|---|---|
| Found in | Grape skins, red wine, peanuts | Blueberries; a close chemical relative of resveratrol1 |
| Absorption in people | At least 70% absorbed, but only trace unchanged resveratrol in blood2 | No human data in the sources checked |
| Absorption in rats (same study) | About 20% bioavailable1 | About 80% bioavailable1 |
| Main human finding | Lower insulin resistance and HbA1c; fasting glucose only in diabetes3 | 250 mg a day: blood pressure down about 7.8/7.3 mmHg4 |
| Cholesterol | Not the focus of the sources checked | Alone, LDL up about 17 mg/dL; not seen with grape extract4 |
| Safety data | 0.5 to 5 g a day for 29 days; 2.5 and 5 g caused stomach and bowel symptoms5 | Up to 250 mg a day for 6 to 8 weeks: no liver, kidney or glucose harms6 |
In rats given equal molar doses for 14 days, pterostilbene was about 80% bioavailable and resveratrol about 20%, and blood levels of pterostilbene were markedly higher.1 That is an animal study; we found no human study measuring both.
In 6 people, at least 70% of a 25 mg resveratrol dose was absorbed, but the gut and liver converted it so fast that only trace amounts of unchanged resveratrol reached the blood.2
Resveratrol: a 2022 meta-analysis of trials found lower insulin resistance and HbA1c, and lower fasting blood sugar only in people with diabetes, with results that varied a lot between studies.3
Pterostilbene: in 80 adults with high cholesterol taking it for 6 to 8 weeks, 125 mg twice a day lowered systolic blood pressure by about 7.8 mmHg and diastolic by 7.3 mmHg, but pterostilbene alone raised LDL by about 17 mg/dL. The LDL rise was not seen when combined with grape extract and seemed smaller in people on cholesterol medicine.4
If you take diabetes, blood pressure or cholesterol medicine, tell your prescriber. These are study protocols, not personalized advice; confirm any dosing with your prescriber. More detail: the Resveratrol (trans-Resveratrol) and Pterostilbene guides.