A cross-sectional study was carried out among 39 current smokers (CS) and 60 noncurrent smokers (NCS) to evaluate the effects of cigarette smoking on folate and vitamin B-12 concentrations in the circulation and in tissues directly exposed to cigarette smoke. Univariate analysis showed significantly lower plasma, red blood cell (RBC), and buccal mucosa (BM) folate and BM vitamin B-12 concentrations in CS compared with NCS. The association between smoking and folate and vitamin B-12 concentrations in plasma, RBCs, and BM cells was reduced after other variables were controlled for. Total folate intake and plasma vitamin C concentrations were significant predictors of plasma and RBC folate concentrations. The plasma and RBC concentrations of folate were significantly lower in subjects who had last smoked < 1 h before the blood sample was drawn than in subjects who had smoked earlier. At the current recommended dietary allowance (RDA) for folate, CS had 42% lower plasma folate concentrations than NCS, whereas at an intake three times the RDA, the plasma folate concentration was the same for CS and NCS. The results also suggested that CS have BM folate and vitamin B-12 concentrations that are lower than those of NCS.

According to both traditional positivist approaches and also to the sociology of scientific knowledge, social analysts should not themselves become involved in the controversies they are investigating. But

The objective of the study was to document the existence of localized deficiency of folate in a tissue exposed to cigarette smoke, by analysis of oral and circulatory levels of this vitamin in smokers and non-smokers. Buccal mucosal cells and blood samples were collected from 25 smokers and 34 non-smokers. The Health Habits and History Questionnaire was completed by each subject. A 96-well plate L. casei assay, along with preincubation with a folate-free chick pancreas pteroyl-gamma-glutamyl hydrolase, was used to quantitate total buccal mucosal cell folates. The reproducibility (CV 5 to 7%) and recovery (95 to 106%) of the folate assay were satisfactory. Smokers had significantly lower buccal mucosal cell folate levels than did non-smokers. The mean plasma folate level of smokers although within normal limits, was also significantly lower than that of non-smokers. There were no significant differences in mean dietary folate intake or in alcohol consumption between the 2 groups. The strength of the positive association between smoking and plasma and buccal mucosal cell folate deficiency (by any definition) was moderate to strong and statistically significant. Our results indicate that cigarette smoking may result in a localized folate deficiency in buccal mucosal cells, independent of the plasma folate levels.

This paper reconstructs and analyzes the content and context of the debate over the efficacy of vitamin C in the treatment of cancer, and compares it with medical responses to, and evaluations of, two other cancer drugs — the cytotoxic drug SFU (conventionally used in the treatment of gastro-intestinal cancers) and the `naturally-occurring' (but recombinant DNA-produced) drug interferon. This comparative approach is designed to facilitate the integration of microsociological and structural levels of analysis of the processes by which knowledge claims about therapeutic efficacy are evaluated by the powerful adjudicating medical community. It is argued that the assessment of medical therapies is inherently a social and political process; that the idea of neutral appraisal is a myth; that clinical trials, no matter how rigorous their methodology, inevitably embody the professional values or commitments of the assessors; and that judgements about experimental findings may be structured by wider social interests, such as consumer choice or market forces. It is concluded that the necessarily social character of medical knowledge cannot be eliminated by methodological reform, and that this has important implications for the social implementation of medical therapies and techniques.