I don't think you can truely reverse the damage you've done.
dave they did a study and paid college professors,etc,..for 15 years..that smoke 1.5 to 2 packs a day.
after 15 years the smokers who took vitamin c was nea a person that did not even smoke.
here is just a little about vitamin c and smoking.
Vitamin C may offer important protective benefits for smokers and those who are passively exposed to tobacco smoke. Smoking has been linked with elevated levels of C-reactive (CRP) protein, an inflammatory marker linked with an elevated risk of cardiovascular disease. As Life Extension readers know, it is crucial to monitor your CRP levels through regular blood testing and to keep your CRP under control in order to limit cardiovascular problems. Fortunately, vitamin C has been shown to play a role in helping to combat excessive CRP levels.
Researchers in Berkeley evaluated the impact of antioxidant supplementation on blood levels of CRP in both active and passive smokers.24 They studied 160 healthy adults who were actively or passively exposed to cigarette smoke and randomly assigned to receive placebo, vitamin C (515 mg/day), or an antioxidant mixture (including vitamins C, E, and lipoic acid). Subjects in the vitamin C group underwent a significant 24% reduction in their plasma CRP concentrations, while neither of the other groups showed a significant change. This remarkable result provides strong support for chronic supplementation with vitamin C, whether or not you smoke.
Smoking causes cancer in part by directly damaging DNA, which is a vital first step in the onset of cancer. In studying the effect of vitamin C supplements on reducing DNA damage in blood cells, Danish researchers gave relatively low doses (500 mg/day) of vitamin C as plain-release or slow-release tablets combined with vitamin E (182 mg/day), or placebo, for four weeks to a group of male smokers.25 The slow-release formulation of vitamin C reduced the number of DNA damage sites measured in white blood cells just four and eight hours after a single tablet, a positive result that was still evident at four weeks. The plain-release tablets also exerted a protective effect at four hours, suggesting benefits of long-term vitamin C supplementation in minimizing DNA damage.
Once DNA is damaged, however, smoking induces pro-inflammatory changes that can allow a malignant cell to become a dangerous tumor as well as causing blood vessel damage associated with atherosclerosis. Vitamin C supplementation is a logical approach to reducing the impact of these inflammatory changes, as was shown recently by a British investigative team.15 They studied 10 smokers with the high-risk lipoprotein ApoE4 gene as well as 11 non-smokers, all of whom took just 60 mg/day of vitamin C for four weeks. Remarkably, these high-risk smokers on this low-dose regimen responded with a marked reduction in levels of a host of pro-inflammatory cytokines. As the authors themselves pointed out, this study identified core molecular mechanisms that help explain the known benefits of vitamin C supplementation in smokers.
Literally scores of other studies have been published demonstrating the benefits of vitamin C supplements in smokers and those passively exposed to cigarette smoke. One study found that 500 mg of vitamin C twice daily for just two weeks reduced the depletion of vitamin E caused by smoking by up to 50%.26
Two other studies investigating low and high doses of vitamin C supplementation revealed its benefits in improving endothelial function, a cornerstone of cardiovascular health, known to be impaired in smokers. The first study showed that just 60 mg of vitamin C daily given to a group of smokers for 12 weeks improved endothelial function as assessed by flow-mediated vasodilation.27 In the second study, Dutch researchers found that 2,000 mg/day of vitamin C for two weeks reversed endothelial dysfunction caused by the abnormal migration of monocytes7 implicated in atherosclerosis.28
Furthermore, Berkeley public health researchers successfully reduced levels of F2-isoprostanes, a sign of oxidative stress and cell damage, in a group of 67 passive smokers who were given vitamin C supplements daily for two months. The researchers stressed the value of these findings in preventing tobacco smoke-induced health damage in non-smokers.14