Cancer and Vitamin C
Recent findings led researchers at McMaster University to reexamine what is now known about vitamin C – and to look at its relationship to serious aging-related diseases like cancer.
In a 2006 review*, Herb E. Schellhorn, PhD, and master’s degree candidate Yi Li, proposed that pharmaceutical levels of vitamin C in the bloodstream may provide significant treatment benefits for a number of degenerative diseases more likely to occur as people get older.
Evidence reveals “very interesting things”
There are many opinions about the role vitamin C plays in different disease processes, and new information is causing the medical community to reexamine that role, says Schellhorn, adding that significant recent findings fall under two broad categories:
• “There is growing recognition that many aging-related diseases (including cancer, heart disease, and neural degeneration) may have a contributing oxidative damage factor that can be reduced by dietary antioxidants such as vitamin C,” he says.
• “We’re seeing evidence that Vitamin C does some very interesting things that no one even suspected until recently,” Schellhorn.says. “For example, there are new findings that it’s related to respiratory development and stem cell differentiation – which also could have big implications for heart disease.”
So the primary reason behind the review, he says, was “to focus at attention on the idea that we should look not only at our consumption of vitamin C, but also at the reasons why we’re consuming it.”
An enzyme produced by the body specifically to get rid of free radicals, vitamin C generates a lot of physiological antioxidants – and, Schellhorn says, data suggests that this nutrient is “a key player” in the disease process of some cancers.
Recommended daily allowance increased, more studies needed
The problem is, we humans (as well as other primates) developed mutations of the genes that activate vitamin C production million of years ago. Virtually all animals, except humans, primates, and guinea pigs, manufacture vitamin C from their own blood sugar. Scientists have studied mice, rats, cows, goats, sheep, squirrels, gerbils, rabbits, cats and dogs to determine their daily rate of vitamin C production.
Another reason is that, “with respect to cancer and other diseases, the role of vitamin C is hard to evaluate in humans because we really need to look at someone’s diet over a lifetime,” Schellhorn says. “Short-term human studies don’t account for a lifetime of accumulation – or of deficiency, which could predispose some people to cancer.”
Schellhorn says that because Vitamin C is quickly oxidized in the body under normal conditions, “it’s really no good as an antioxidant until it reaches a near-saturation level in the bloodstream” – a level that would be virtually impossible (and undesirable) to achieve by mouth alone.
Although Schellhorn defines a pharmacological level as being one that is higher than the level someone might easily consume in a balanced diet, “the levels we’re talking about here can be achieved intravenously or through intramuscular injection only,” he says, adding that while vitamin C is “remarkably non-toxic” overall, patients with iron-uptake disorders such as hematomachrosis should exercise caution.
Schellhorn also advises patients to be sure their doctors are up to date on the latest information about vitamin C. For instance, in 2000, the recommended daily allowance of 60 milligrams for adults (70 for pregnant women) was increased to 75 milligrams for all women, and 90 milligrams for men.
As always, people should speak with their doctors if they are considering using any vitamin supplement in any form.