Effect of smoking cessation on plasma ascorbic acid concentration

Abstract

Numerous studies have shown that cigarette smokers have a lower plasma concentration of ascorbic acid than non-smokers, but only a few have considered the antioxidant status of ex-smokers.' We report the first controlled study monitoring the early effect of smoking cessation on the concentration of ascorbic acid in plasma. Subjects, methods, and resultsThe study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the local ethics committee. Two hundred volunteers were recruited through local advertisement and gave signed informed consent. Eligible subjects of both sexes (aged 35 to 65 years) had smoked at least 15 cigarettes a day for one year and declared motivation to stop. Exclusion criteria were known presence of disease; daily intake of drugs, including hormonal contraceptives; antioxidant supplements within the last month; and pregnancy or breastfeeding.Subjects (n = 182) were assigned by a computer generated random number list either to stop smoking immediately (quitters group, n = 100) or to continue smoking for four weeks (smokers group, n = 82). After four weeks, those in the smokers group left the study and were offered a smoking cessation programme. During the 26 weeks of the study, subjects in the quitters group visited the clinic seven times. Smoking cessation was aided by nicotine patches releasing 15 mg nicotine daily (16 hours; Nicorette, Pharmacia AB, Helsingborg, Sweden).2 After 12 weeks, dosage was reduced during a four week period. None of the subjects used nicotine patches after 26 weeks. After four weeks, the quitters group consisted of 62 subjects and the smokers of 72. The remaining 48 subjects did not succeed in stopping smoking, suffered from acute illness, used intercurrent antioxidant supplements, or withdrew their consent. After 26 weeks, 41 subjects in the quitters group were still not smoking; 28 of these fulfilled the remaining criteria.At the entry and four week visits, fasting blood samples were collected from both groups. The quitter status of the subjects was confirmed at each visit by measurements of end-expiratory carbon monoxide and plasma cotinine.Total ascorbic acid was measured using high performance liquid chromatography with coulometric detection as previously described.3 T tests were used to analyse differences within groups; analysis of covariance with baseline adjustment was used for differences between groups; and intention to treat analysis was used for confirmation.Four weeks after the start of the study, the plasma concentration of ascorbic acid had increased by an average of 23.3% (P<0.001) in the quitters group and 9.8% (P<0.05) in the smokers group (difference 13.5%, P<0.05). Intention to treat analysis showed similar results for the quitters group (21.2%, P<0.001; n = 90) and the smokers group (10.2%, P<0.05; n = 77) (difference 10%, P = 0.06).After 26 weeks, the ascorbic acid concentration had increased by 21.2 % (P<0.005) from baseline in the quitters group as compared with baseline. There was no significant diff...

The effects of combined antioxidant (β‐carotene, α‐tocopherol and ascorbic acid) supplementation on antioxidant capacity, DNA single‐strand breaks and levels of insulin‐like growth factor‐1/IGF‐binding protein 3 in the ferret model of lung cancer

“…In the present study, the plasma concentrations of both total AA and reduced AA were significantly lower in the SM1NNK group compared with the control group (Table III), which is in concordance with the previous human studies showing lower plasma levels of AA in smokers. 44,45 However, the plasma total AA and reduced AA in ferrets with smoke exposure and NNK treatment was not restored to control levels by AOX supplementation. This could be because of either a dose of smoke exposure that overly depleted AA or an insufficient dose of AA, even though ferrets synthesize their own AA.…”

“…42 In the ATBC trial, subjects were given both b-carotene and vitamin E but without vitamin C. Vitamin C has been shown to protect against in vivo oxidation of lipids and DNA in humans, particularly in persons exposed to enhanced oxidative stress, such as smokers. [43][44][45] The lower vitamin C status of smokers is most likely because of the increased turnover of the vitamin as a result of increased oxidative stress. 46,47 Although plasma AA levels were not reported in the ATBC study, 42 lower levels of plasma AA would be expected among the smokers.…”

Vitamin C modifies the cardiovascular and microvascular responses to cigarette smoke inhalation in man

“…However, it is known that plasma vitamin C levels are depressed in smokers, and that this relates to smoking itself rather than to depressed dietary intake [26]. Vitamin C is known to block the effect of inflammatory platelet activating factor mimetics, which are activated within minutes of exposure to cigarette smoke in hamsters [27].…”

Determination of ascorbic acid in individual rat hepatocyte by capillary electrophoresis with electrochemical detection

“…Ascorbic acid (AA) is one of the most important cellular antioxidants [1,2] and a valuable biomarker of oxidative stress [3][4][5]. It has been found that AA can inhibit viral infectivity by inactivating viruses and by affecting viral replication.…”