OPC Antioxidant Reference Guide
Oligomeric Proanthocyanidins

OPC sources have traditionally been pine bark and grape seed. These substances contain substantial amounts of four chemically similar molecules that have varying degrees of antioxidant ability. The most basic form, and least potent antioxidant, is epicatechin (EC). Then come epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG), which is the most potent antioxidant form.

It makes sense that both researchers studying OPCs and marketers selling them would focus on the content of EGCG, since it is the most potent antioxidant. There is a spirited debate over which OPC source provides more EGCG, with the adherents of pine bark contesting grape seed’s OPC content, and vice-versa. Grape seed proponents, for example, claim that pine bark does not contain any EGCG, which is their argument for why grape seed extracts are better products than pine bark products.

In fact, it would be unlikely to find that pine bark does not contain EGCG. All plants that have been studied for their OPC content have been found to contain a mixture of all four forms of the substance. For pine bark to not contain EGCG would make it unique to the plant world. This is not impossible; it just is not very probable.

A new substance has burst upon the scene—green tea. Researchers in Asia have been looking at tea for years, as there have been many causal links between green tea consumption and health. They have discovered that green tea contains much more EGCG than either pine bark or grape seed. The content of EGCG in grape seed is about 15 percent of the total OPCs present. In green tea extracts, the amount of EGCG is 50 percent of the total OPCs present.

However, more of one form of OPC does not necessarily mean better. The other OPC forms "EC, EGC, and ECG" provide unique benefits. So, although some studies have found EGCG to be more effective than the three other OPC forms, in some situations it is less effective. For example, in tests of the effects of OPCs on reducing blood pressure, EGCG was found to be 15 times less effective than ECG. In tests investigating the ability of OPCs to destroy bacteria, EGCG was most effective at inhibiting some bacteria, but less effective at inhibiting others.