Vitamin C cures the common cold! Well, at least that's what the rumor said, the one that kept us running for the C bottle at the first sign of the sniffles. Vitamin C is the new hope for preventing or treating cancer! That's what numerous studies from the 1970s seemed to indicate. This information was reported 30 years ago in the journal Proceedings of the National Academy of Sciences by the two-time Nobel Prize laureate, Linus Pauling, and his colleague Ewan Cameron, a surgeon from Scotland, and later presented in the book "Vitamin C and Cancer," also by Cameron and Pauling.
The radical idea that very high doses of vitamin C could extend the lives of cancer patients became the subject of heated debate and stimulated researchers at the Mayo Clinic, Rochester, Minn., to embark on C and cancer studies in 1978.
When the results from the Mayo Clinic studies revealed no beneficial effect of high doses of vitamin C, some of the steam seemed to go out of the vitamin C miracle, at least with regard to curing cancer, thus shoving the whole affair in the direction of an urban legend.
We have a short attention span when it comes to dietary miracles. "What have you done for me lately?" seems to be the operative phrase. So if vitamin C isn't acting like a miracle drug, we tend to take it for granted rather than appreciate it for the subtle and vital benefits it provides. We've moved on to other superheroes, antioxidants with color and panache for example resveratrol, an antioxidant in red wine.
Resveratrol is a legitimately healthy phytochemical, but it's in the spotlight lately thanks to recent animal studies suggesting might offer protection from the negative health effects of obesity, without the need to diet. Eat fast food without suffering poor health and drink lots of wine? Now that's a sexy message.
Ok, it's not exactly what the study said, and the mice did consume an amount of resveratrol that would be equal to you and me consuming gallons of wine per day, but it still makes vitamin C sound boring.
But vitamin C seems to be getting a second look. After all, C is not only another antioxidant, it's a vital nutrient – one without which we cannot live. You could say it still has genuine superstar cachet.
A special kind of nutrient
We need vitamin C in order to make collagen, the support structure of tendons, ligaments, blood vessels, and scar tissue. Its role in the synthesis of carnitine, a molecule needed to transport fatty acids into mitochondria, makes the vitamin critical to our energy needs.
In addition to structure and energy, vitamin C affects brain function by aiding in the synthesis of the neurotransmitter norepinephrine. Recent research suggests C might even lower cholesterol since it helps convert it to bile acids used in fat digestion.
As an essential nutrient, vitamin C's reputation as an antioxidant is solid. Vitamin C acts to protect cells from the damage to membranes, proteins and DNA created by reactive oxygen compounds, natural byproducts of metabolism. It also helps to guard us against environmental pollutants, like cigarette smoke, and even certain forms of air pollution. To a degree, vitamin C may be considered a lung protector.
Guidelines for C have changed over the years. Only about 10 mg are necessary to stave off scurvy. The first versions the RDA set the need for vitamin C at 60 mg for adult males considered a generous margin of error for the prevention of scurvy at the time. But in recognition of its role as an antioxidant, offering general protection against chronic diseases, the RDA has been raised to 90 mg for males and 75 mg for females. For smokers, the figure is set at 125 mg and 110 mg respectively.
At present, there aren't enough convincing studies to prove that supplementation with high doses (well beyond RDA levels) of vitamin C will protect against chronic disease. But there are plenty of studies that link intake of vitamin C-rich foods (fresh fruits and vegetables) with protection from a variety of chronic diseases, including cardiovascular disease and cancer. There is little doubt that oxidative damage and chronic disease goes hand in hand.
Out of retirement
Several recent studies suggest vitamin C given in high doses (3000 mg per day) prior to activity may offer protection against the oxidative stress placed on the body by intensive exercise. The idea is that the greatly increased rate of metabolism and oxygen consumption results in more reactive oxygen species.
This makes vitamin C of special interest to athletes, and is, in part, one of the reasons for its inclusion in many sports/energy drinks of late. But how about those of us not in training for Beijing in 2008?
Depending on current research looking into vitamin C and the synthesis of body fat, vitamin C could grab even more attention soon. The plausible mechanism goes something like this: Low levels of vitamin C in the blood make it more difficult to oxidize fatty acids to energy, so more of them get used to form triglycerides, the storage form of fat. If you consider that a significant portion of the population does not even meet the older RDA level of vitamin C, let alone the newer guidelines, this could be important.
It's still hard to get people to eat the relatively minimal five fruits and vegetables per day. Even meeting that amount will not guarantee the requisite amount of vitamin C, since not all fruits and vegetables are rich sources, and cooking is notoriously destructive of vitamin C. It's easy enough to take a pill, but not everyone likes taking pills. So if this line of research even hints at the possibility that vitamin C can fight obesity, it won't be long until we see a surge in products spiked with vitamin C to promote weight loss.
That's when you can say that vitamin C has officially made a comeback.