Cigarette smoke affects plasma fatty acid levels : an in vivo study

Cigarette smoke (CS) contains thousand of compounds, mainly free radicals, that affect polyunsaturated fatty acids (PUFA) levels. In vitro, in different cell lines, CS inhibits the conversion of n-3 and n-6 fatty acids (FA) to their longer and more unsaturated derivatives. In vivo studies on the effects of CS on PUFA metabolism are scarce. Objective: to compare the FA profile in smoking (S) vs non smoking persons (NS). Methods: 12 S and 12 NS hyperlipidemic subjects were selected. FA in total lipids (TL), phospholipids (PL), triglycerides (TG) and cholesterol esters (CE) were analyzed by GC. Results: TG, LDL, HDL, glycemia, BMI and age are similar in the two groups. Although S show lower total cholesterol (TC) levels, their plasma oxysterols are higher (+53%) vs NS. In TL, S present higher levels of saturated (SFA) and monounsaturated FA (MUFA) vs NS. On the contrary PUFA are decreased: linoleic acid (LA, 18:2 n-3), arachidonic acid (AA, 20:4 n-6) and docosahexaenoic acid (DHA) are reduced in S than in NS. In addition, S present lower levels of PUFA in PL, TG and CE and higher levels of MUFA and SFA in PL and CE. The ANOVA linear regression shows, in TL, positive correlation between LA levels and TC, LDL only in NS. The correlation found in S is positive between 18:0 and TC, LDL, HDL; between SFA and TG; negative correlation between DHA and TC, EPA, DHA and TG. The relationship between FA levels and cigarette number or years of smoking were also investigated. Conclusions: Cigarette smoke significantly affects FA composition in TL, PL, TG and CE; S show decreased levels of PUF A and increased levels of SFA in relation to the number of years of smoking, while no correlation was seen between FA levels and number of cigarettes per day.