September 18, 2007
New research sparks new theories about how vitamin C inhibits cancerous growth.
A great deal of research indicates that vitamin C has a considerable inhibitory effect on the growth of cancer cells.
The biochemical effect of high-dose treatment with vitamin C is reasonably understood; vitamin C acts as a pro-oxidant on cancer cells at such doses. This causes increased free radical strain on the cancer cells and thereby acts as a poison to the cancer.
In moderate doses, the kind of doses which we can get through our diets, vitamin C is an antioxidant. But even at these doses, vitamin C has shown an inhibitory effect on the growth of cancer cells.
It was therefore believed that vitamin C blocks the free radicals which cause the cancer forming mutations in the cells, and that the reason for its protective effects is that it protects the cells’ DNA.
This is presumably not the whole truth.
Many years ago a famous professor by the name of Warburg was among the first to maintain that cancer cells grow in oxygen poor tissue. Today this is common knowledge, but there lacks knowledge on how this occurs. Ten years ago Gregg Semenza of John Hopkins University found that cancer cells are dependent on a protein called HIF-1 (hypoxia induced factor), which helps the cells by compensating for lacking oxygen in the surrounding tissue and thus allows cancer cells to convert sugar to energy without oxygen. HIF-1 also catalyses the creation of new blood vessels so that hungry cancer cells can get fresh supplies of nutrients and oxygen. If a cancer grows aggressively, it quickly uses up its oxygen supply and becomes entirely dependent on HIF-1. The HIF-1 protein is dependent on the presence of free radicals, which are also necessary for many other processes in the body. A powerful antioxidant like vitamin C eliminates the surplus of free radicals, which causes HIF-1 to become ineffective and thus inhibits cancer growth.
This new theory is based on a study done by a research group at the centre of oncology at John Hopkins University in conjunction with Dean Felsher of Stanford.
They set out to study antioxidants’ roles in cancer growth and found, to their great surprise, that antioxidants destabilise the protein on which cancer cells are dependent. As professor Chi Dang from John Hopkins University wisely stated, “By uncovering the mechanism behind anti-oxidants, we are now better suited to maximize their therapeutic use.”
By: Claus Hancke, MD
HIF-Dependent Antitumorigenic Effect of Antioxidants In Vivo. Cancer Cell, Volume 12, Issue 3, 11 September 2007, Pages 230-238Ping Gao, Huafeng Zhang, Ramani Dinavahi, Feng Li, Yan Xiang, Venu Raman, Zaver M. Bhujwalla, Dean W. Felsher, Linzhao Cheng, Jonathan Pevsner et al.