In general, oral grape seed extract is used in capsules or tablets containing 50 mg or 100 mg. Insufficient scientific information is known, however, about how long-term use of grape seed extract might affect health or any disease.
 

Grape Seed Extract
 

The following are side-effects and cautions, other NCCAM advisories.

Grape seed extract is well tolerated when taken by mouth, although it is better tolerated when encapsulated, as its taste is bitter. It has been used safely for up to 8 weeks in clinical trials.

Side-effects most often include headache, a dry, itchy scalp, dizziness, or nausea

Interactions between grape seed extract and medicines or other supplements have not been carefully studied

Because of the possible action of proanthocyanidins on limiting platelet adhesion, grape seed extract may act as a blood-thinner, increasing clotting time.

Main functions of grape seed extract:

1. Reduce cancer risk;

2. Antioxidant activity;

3. Anti-inflammatory, removal of swollen;

4. Reduce the incidence of spots and cataracts;

5. Reduce exercise-induced vascular sclerosis porridge;

6. Strengthen the blood vessels the flexibility of the wall.

Regarding the above functions, besides grape seed extract, polygonum cuspidatum extract, resveratrol,sophora root extract and soybean extract also have more or less the same efficacy.

Grape seed extract is also an aromatase inhibitor in vitro, i.e. it may suppress the conversion of testosterone to estradiol.