The Powers of Vitamin C: Research Update

Antioxidants? Vitamin C is still tops
New nutrients - from the bioflavonoids to alpha lipoic acid - have moved to the forefront as important antioxidants over the past decade. However, vitamin C or ascorbic acid still remains one of the most important antioxidants we need to help maintain optimal health. There is a renewed interest in investigating the benefits of vitamin C, as evidenced by these three studies published in the last several months.

Vitamin C Reduces Risk of Clogged Arteries in Children
A study conducted at UC San Francisco found that children and young adults who have inherited high cholesterol may reduce their risk of clogged arteries by taking supplements of vitamin C and E (1). Investigators gave children with high cholesterol levels daily doses of 500 mg C and 400 IU E or placebo for six weeks. Blood flow and dilation in the brachial artery was significantly improved in the children receiving antioxidants. According to the researchers, the vitamins improve blood flow through the arteries and may prevent damage that leads to atherosclerosis or hardening of the arteries. This study is the first to show that vitamins can reverse blood vessel damage.

Vitamin C May Help Reduce the Risk of Ulcer
Investigators at the San Francisco VA Medical Center report that the lower the level of vitamin C in blood, the more likely a person will become infected by Helicobacter pylori-the bacteria that can cause peptic ulcers and raises the risk of stomach cancer (2). The researcher drew on data and blood samples collected from a random sample of nearly 7,000 adults during the 3rd National Health and Nutrition Examination Survey (NHANES III). According to the researchers, they can't be absolutely certain whether H. pylori infection lowers blood levels of C, or if higher C levels protect against infection. However some studies using animal models suggest that adequate vitamin C intake may reduce infection with this bacteria. "The bottom line is that higher levels of vitamin C may have the potential to prevent peptic ulcers and stomach cancer", according to lead author Dr. Joel Simon.

Vitamin C Reduces Oxidative Stress
A research team from UC Berkeley found new evidence that for people exposed to environmental tobacco smoke, vitamin C can significantly reduce levels of oxidative stress - a process associated with a wide variety of chronic diseases. In the study (3), researchers tested for a sensitive biomarker of oxidative damage to lipids (fats) called F2 isoprostanes. Groups of non-smoking adults got one of three supplements: 500 mg vitamin C; a daily mixture of vitamin C, alpha-lipoic acid, and vitamin D; or a placebo. After 2 months of treatment, the biomarkers dropped significantly in both groups taking supplements compared to those getting the dummy pill. The difference in biomarker reduction between those getting vitamin C alone and the group receiving the mixture was not statistically different, suggesting that the key antioxidant at work is vitamin C.

Many Americans Get Too Little Vitamin C
These findings underscore the multi-faceted ways in which vitamin C supports good health. But a major concern is that many Americans are not getting enough dietary vitamin C - or vitamin E - in order to reap their benefits. Several years ago researchers assessing dietary patterns and blood levels of both vitamins in adults from NHANES III found that:

• Fully 2/3 do not consume 5 fruit and vegetable servings daily
  
• One-third have low blood levels of vitamin E
  
• One-fourth have marginal blood levels of vitamin C
  

The" take home" message? Include more antioxidant-rich fruits and vegetables in your diet and help close the antioxidant gap with supplements providing meaningful amounts of vitamins C and E.

References

1. Engler MM et al. Antioxidant vitamins C and E improve endothelial function in children with hyperlipidemia: Endothelial Assessment of Risk from Lipids in Youth (EARLY) Trial. Circulation 108:1059-63.
2. Simon JA et al. Relation of serum ascorbic acid to Helicobacter pylori serology in US adults: the Third National Health and Nutrition Examination Survey. J Am Coll Nutr 22:283-9, 2003
3. Dietrich M et al. Vitamin C supplementation decrease oxidative stress biomarker F2 isoprostanes in plasma of non-smokers exposed to environmental tobacco smoke. Nutr Cancer 45:176-84, 2003.