Atherosclerosis is one of the important medical problems in modern society. Tobacco smoking, including passive smoking, is one of the important risk factors. Moreover, studies have demonstrated that high environmental smoking pollution is associated with an accelerated atherosclerotic process (Vitamin B12 supplementation smokers).

Previous studies have shown that vitamin B12 and C supplementation improves vascular reactivity and may be beneficial for vascular protection. Therefore, to further assess the effect of vitamin supplementation on atherosclerosis in subjects exposed to high environmental tobacco smoke, the researchers designed a double-blind 2×2 factorial design in which 91 passive smoker’s casino employees (19.2% of whom were men, mean age 45.0±8.2 years) were randomized to receive vitamin B12 (500 μg per day), vitamin C (200 mg per day), vitamin B12+C, or image-matched placebo capsules for 1 year. Brachial artery reactive (FMD) and carotid intima-media thickness (IMT) (surrogate markers of atherosclerosis) were measured by ultrasound at baseline and at 12 months.

Of the 78 (85.7%) passive smoking employees who completed the study, 11.5% had hypertension, 5.1% had diabetes mellitus, and 15.4% had hypercholesterolemia. Their blood pressure, lipid profiles, glucose, and body mass index did not change significantly after 1 year of supplementation, but diastolic blood pressure (DBP) and blood creatinine decreased mildly after combining vitamin B12+C, and blood B12 increased significantly after supplementation with vitamin B12 and vitamin B12+C. Humeral FMD and carotid IMT improved after the 3 vitamin supplementations but not after the placebo, with the improvement being more significant after combined vitamin supplementation, and no adverse effects were reported (as shown in the figure below).

In conclusion, vitamin C and B12 supplementation alone or in combination for 1 year improved vascular reactivity and structure in chronic passive smokers, suggesting a benefit for long-term atherosclerosis prevention.

Woo, K. S., Yip, T. W. C., Chook, P., Koon, K. V., Leong, H. C., Feng, X. H., … & Kwok, T. C. Y. (2021). Vitamins B-12 and C supplementation improves arterial reactivity and structure in passive smokers: implication in prevention of smoking-related atherosclerosis. The journal of nutrition, health & aging, 25, 248-254. [Link]