Which brands have been tested by independent consumer organizations for potency, purity and compliance with label claims?

Consumer Lab tested the major brands of resveratrol in mid November and found that not all products contained the amount of resveratrol claimed on their labels and web sites. Life Extension brand, for example contained less than 27% of the claimed resveratrol.

Biotivia Bioforte was the best value per 100mg and second highest potency product and Biotivia Transmax was the highest potency supplement of those which passed the ComsumerLab.com evaluations, and was the only company with two approved products. The test was open to all manufacturers however many chose not to subject their products to independent scrutiny.