As a chiropractor I regularly have patients who want to take an active role in their healthcare. They want to eat right, exercise efficiently, and use supplements wisely. One of most common self-treatments I encounter is the regular use of high doses of vitamin C. The main reasons patients give for taking vitamin C fall into two camps: boosting the immune system and avoiding chronic diseases such as heart disease, cancer, and dementia.
Unfortunately, there is a great deal of research to show that people are actually harming themselves by taking vitamin C. One of the most recent and eloquently done studies sheds light on the mechanisms by which supplemental vitamin C causes harm. The study was published in January of 2008 in The American Journal of Clinical Nutrition. The researchers took a group of "healthy, sedentary men" and divided them into 2 groups. Group A did routine aerobic exercise for 8 weeks and took no supplements. Group B did the same workout program, but took 1 gram (1,000 milligrams—the amount found in many popular supplements) of vitamin C per day.
The researchers measured a key marker of endurance fitness called the VO2max before and after the study. The group that did not take vitamin C improved 22%, and the group that took vitamin C improved 10.8%
Put another way, the group that took the vitamin C achieved less than half of the aerobic gains that the non-supplementing group experienced! The interesting part is why, and here it is in a large nutshell.
Exercise in and of itself creates free radicals. These free radicals then trigger the body to make two major antioxidant enzymes: superoxide dismutase and glutathione peroxidase. These two antioxidants are incredibly powerful neutralizers of free radicals and they appear to be part of a signaling system that causes the body to make mitochondria. Mitochondria, in turn, are the "energy factories" of our cells. Increasing their numbers gives us increased capacity to create energy for endurance, as well as every other cellular activity. The researchers in this study found that taking vitamin C inhibited the body's natural antioxidant pathways as well as the creation of new mitochondria—these people had les superoxide dismutase, less glutathione peroxidase, and fewer mitochondria in their cells.
The bottom line is this: if you take supplemental vitamin C daily you decrease your body's natural antioxidant defense system and literally sabotage your capacity to create energy. Millions of Americans are taking 1,000mg of vitamin C or more every day without even thinking about it. Many fatigue-related diseases such as chronic fatigue and fibromyalgia are related to problems with mitochondrial function. Ironically, victims of these disorders are often the ones taking high doses of vitamin C because they think it’s going to help them with energy!
Other research has shown that taking supplemental vitamin C is associated with increased risk for cardiovascular disease in women with diabetes (Lee 2004), and that is acts as a “pro-oxidant” rather than a antioxidant in many circumstances (Podmore 1998). Some studies show that “free iron” in the presence of vitamin C leads to oxidative damage (Rocha 2005). In our bodies “free iron” can result from strenuous exercise, excess dietary iron, and from certain oxidative diseases such as Parkinson’s. It is likely that supplemental vitamin C will be more damaging in these situations.
A recent study published in the Journal of the American Medical Association reported that chronic use of the antioxidants A, C, E and beta carotene led to a five percent increase in mortality (Bjelakovic 2007).
All of the above is true in regards to supplemental vitamin C only. Dietary vitamin C is another story. Every study that looks at dietary vitamin C that I have seen demonstrates that it is protective against oxidative diseases such as heart disease, cancer, and dementia. This is the research that has created the rational for supplementing with vitamin C. What we are seeing, however, is that vitamin C made in a lab does not affect the body in the same way as the vitamin C that we find in food. There are many theories as to why this is, most of it pointing the complex interactions of the thousands of chemicals present in food that we have evolved to use in our bodies, as opposed to high levels of a single molecule (ascorbic acid) produced in a laboratory. There is just no substitute for whole foods!
Foods high in vitamin C include citrus fruits, red, yellow, and orange peppers, papaya, mango, broccoli, tomatoes, kiwi, and potatoes. Longer lists can be found online—I recommend eating at least two servings of vitamin C containing foods everyday. Triphala, an Ayurvedic blend of three berries, contain nature’s highest source of vitamin C and is available at my office.