You’re probably quite familiar with grape seed extracts, especially for heart-related conditions. Unfortunately, many supplemental forms on the market are either so adulterated with other ingredients, or so encumbered with tannins – compounds that limit absorption – that they are virtually useless.

However, grape seed extracts that are free of tannins, allow their beneficial components, called oligomeric proanthocyanidins or “OPCs”, to absorb fully in the digestive tract and ultimately enter into the cells that most need their healing attention.

This study tested grape seed oligomeric proanthocyanidins (OPCs) against a plain, or “unfractionated” grape seed extract (GSE) that was not tannin-free, nor specifically standardized for the compounds. One of the insights garnered by this research was not just how the OPCs affect cancer-related genes and stop the cancer cell growth cycle, but how much more effective the smaller-sized (low molecular weight) OPCs were in comparison with the larger proanthocyanidins from the regular grape seed extract.

These OPCs target specific microRNAs – in this case the microscopic engineers that replicate cancer cells – and suppress cancer by directly inducing apoptosis (cancer cell death). It also boosted levels of tumor suppressor genes, downregulated tumor promoting genes, and prevented the migration of cancer cells.

Although this research focused on colorectal cancer, there are similar types of activity across nearly all kinds of malignancies. In fact, the researchers found that the grape seed worked along so many tracks that in their study they mention, “…no single clinical therapeutic has the ability to effectively block multiple oncogenic pathways…” That alone is an incredible breakthrough.

But in vivo tests found something else even more applicable to everyday life. Because the tannin-free OPCs from French grape seed extract were more absorbable than the tannin-bound OPCs from unfractionated grape seed extract, the botanical ingredient was much more effective at much lower dosages. For example, even at smaller amounts, OPCs were much more effective than standard grape seed extract at reducing tumor size. In just 13 days, 100 mg of OPCs reduced tumor size by 65 percent. Even a 50 mg level brought the tumor size down 40 percent. Compared to standard grape seed extract at only 13 percent and 8 percent, respectively, it shows how much of a difference it makes to get a tannin-free grape seed extract with useful OPCs that can reach their full potential. Additionally, there was no harmful effects on healthy cells – these actions were targeted to cancer cells only. Scaled up for human use, researchers determined that low daily dosages – maybe even only 240 mg per day – were sufficient.

Abstract:

Ravindranathan P, Pasham D, Balaji U, Cardenas J, Gu J, Toden S, Goel A. Mechanistic insights into anticancer properties of oligomeric proanthocyanidins from grape seeds in colorectal cancer. Carcinogenesis. 2018 May 28;39(6):767-777.

Although the anticancer properties of oligomeric proanthocyanidins (OPCs) from grape seeds have been well recognized, the molecular mechanisms by which they exert anticancer effects are poorly understood. In this study, through comprehensive RNA-sequencing-based gene expression profiling in multiple colorectal cancer cell lines, we for the first time illuminate the genome-wide effects of OPCs from grape seeds in colorectal cancer. Our data revealed that OPCs affect several key cancer associated genes. In particular, genes involved in cell cycle and DNA replication were most significantly and consistently altered by OPCs across multiple cell lines. Intriguingly, our in vivo experiments showed that OPCs were significantly more potent at decreasing xenograft tumor growth compared with the unfractionated grape seed extract (GSE) that includes the larger polymers of proanthocyanidins. These findings were further confirmed in colorectal cancer patient-derived organoids, wherein OPCs more potently inhibited the formation of organoids compared with GSE. Furthermore, we validated alteration of cell cycle and DNA replication-associated genes in cancer cell lines, mice xenografts as well as patient-derived organoids. Overall, this study provides an unbiased and comprehensive look at the mechanisms by which OPCs exert anticancer properties in colorectal cancer.