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Subject: Roc, Nutrition Investigator, on study that high Vitamin C Intake reduces stroke risk about 50%

I am preparing a research poster about the latest findings about vitamin C (ascorbic acid, AA). I have found many peer-reviewed artcles in recent times. Because they are so interesting, I decided to send this short summary. Please read below for discoveries like that AA can reduce your risk of stroke by 50%!

Linus Pauling advocated megadoses of AA, but did not know how much would be best. He is reported to have taken 16 g daily. He advocated that it would reduce the risk of both colds and cancer, and there is now evidence that both of those claims are correct. AA also may reduce the risk and progression of many chronic diseases, like arthritis and dementia. But how much to take?

Back in 1994 I discovered that 500 mg of AA once in the morning and again at night saturated a person’s blood with AA, because a single dose passes through the body in just 12 hours. Shortly thereafter, a study at NIH showed that 100 mg of AA twice a day would provide about 85% saturation of serum with AA, while 500 mg twice a day would provide 98% saturation. It is possible to obtain the 100 mg twice a day without supplements if one chooses meals properly. How might your doctor advise between the two dosages?

First, I have long hypothesized that AA might reduce the risk for strokes. Now I have found a study published in Stroke done in Japan over 20 years that found that serum level of AA is inversely proportional to the risk of stroke. For those people in the highest quartile of AA consumption, the occurrence of stroke was reduced 50%! If you are concerned about stroke, you might discuss getting 500 mg twice a day.

At the same time, for those taking AA supplements who experience difficulty in urinating, a recent report in AJCN found that some men (no women were studied) getting more than 250 mg of AA daily may experience LUTS, a condition that makes it difficult to urinate and empty the bladder completely. In this situation, 200 mg in the diet seems worth discussing.

Another study that was recently publicized was one concluding that AA supplements interfere with the benefits of exercise. That study has been widely refuted.

The final controversy recently is a report from Sweden in AJCN that found that AA accelerates the development of cataracts. This contradicts numerous reports of how and why AA reduces the rate of cataracts. However, in Sweden most people take AA in a dosage of 1,000 mg at a time, a rate that may cause someone to exceed the Upper Limit of AA, at which it may transition from an antioxidant to being a prooxidant. The resolution of this question is something I hope to do a research study on.

As the world’s population ages, imagine the savings in cost and suffering if the risk of stroke were reduced 50%. I hope you discuss with your physician whether you ought to get 100 or 500 mg of vitamin C twice a day.

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