Vitamin C
Vitamin C is an essential dietary nutrient required as a co-factor for many enzymes. The reduced form of the vitamin, ascorbic acid, is an especially effective antioxidant owing to its high electron-donating power and ready conversion back to the active reduced form.

There is great interest in the clinical roles of vitamin C because of evidence that oxidative damage is associated with, and may be the root cause of, many diseases. Population studies show that individuals with high intakes of vitamin C have lower risk of a number of chronic diseases, including heart disease, cancer, eye diseases, and neurodegenerative conditions. The evidence that ascorbic acid acts as an important antioxidant in many body tissues is convincing.

Daily Intake Recommendations
Recently the National Academy of Sciences (NAS) issued new recommendations for daily intake of vitamin C for healthy adults, to 90 mg up from 60 mg per day under the previous standard. This revised standard is in part based on the vitamin's role as a powerful antioxidant.  Many government scientists have called for 120-200 mg per day in published reports [Proc Natl Acad Sci 93:3704-09, 1996; Nutrition Reviews 57: 222-24, 1999; Am J Clin Nut 69:1086-1107, 1999] – and this is for healthy non-smokers.  A researcher at the Massachusetts Institute of Technology, Laboratory of Human Nutrition, using a technique called saturation kinetics, suggested that the 200-mg level was not adequate to meet individual vitamin C needs, and healthy people should consume about 400-600mg. [Proc Natl Acad Sci 93: 14344,48, 1996]. The intake level is delivered by consuming 7 to 10 ReplenishMints™  Mints each day.

Vitamin C consumption by Smokers
Tobacco smoke has been shown to reduce vitamin C concentrations in the blood; active smokers have sharply lower levels of vitamin C in their blood, and persons exposed to tobacco smoke also have lowered circulating concentrations of antioxidant nutrients.  For this reason, the National Academy of Sciences Food & Nutrition Board that smokers consume nearly 40% more vitamin C than healthy people (125 mg total).  However, researchers at the Medical College of Wisconsin found that it takes 200 mg of vitamin C before smokers achieve the same serum levels...

of ascorbic acid as non-smokers. [Am J Clin Nut 53: 1466-70, 1991] Other investigators have called for 200-mg daily consumption of vitamin C for smokers. [Ann NY Acad Sci 686: 335-46, 1993]. Swedish investigators demonstrated that a single 2,000 mg dose of vitamin C can completely abolish the typical reduction in blood circulation that occurs while smoking a cigarette. [Microvascular Res 58: 305-11, 1999].

How Much is Too Much?
The Academy of Sciences also set the tolerable upper limit at 2000 mg, but a recent review indicated doses of vitamin C up to 4000 mg. are well tolerated. [Nut Rev 57: 71-77, 1999].  Eight placebo-controlled, double-blind studies and six non-placebo clinical trials in which up to 10,000 mg of vitamin C was consumed daily for up to 3 years confirm the safety of vitamin C in high doses. [J Am Coll Nut 14: 124-36, 1995].
It is important to emphasize that the National Academy of Sciences daily intake and upper limit recommendations apply to healthy non-smokers, not to people under severe oxidative stress because they flood their bodies with cigarette smoke-laden oxidant again and again each day.

The Research
Smokers that took vitamin C supplements (1000 mg) demonstrated significantly decreased oxidation within weeks. University of Texas-Southwestern Medical Center, Dallas.

Free radicals in cigarette smoke cause oxidative damage to proteins, DNA, and lipids, contributing to atherosclerosis, heart disease, and cancer. Antioxidants quench free radicals and ameliorate damage caused by cigarette smoke. University of California at Berkeley.

Levels of vitamin C were significantly lower in the blood of children exposed to cigarette smoke than in unexposed children who consumed equivalent amounts of vitamin C. This reduction in plasma ascorbate occurred even with very low exposure to tobacco smoke. Children exposed to tobacco smoke should consume increased amounts of vitamin C. University of Puerto Rico, San Juan.

Similar research conducted by the Robert Wood Johnson School of Medicine, New Brunswick, New Jersey.

Oxidative damage caused by cigarette smoke is also almost completely prevented by ascorbic acid (Vitamin C), and adequate intake of vitamin C may help smokers evade degenerative diseases associated with oxidative damage from cigarette smoke. Calcutta University, India.

Higher intake of vitamin C is associated with the decreased risk of heart disease in a population with a high prevalence of smoking. Yonsei University College of Medicine, Seoul, Korea.

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