Background:
Vitamins B9 and B12 are essential for many bodily functions. Circulatory levels of the vitamins are affected by cigarette (Cg) smoking. However, the effect of waterpipe (Wp) smoking on circulatory vitamin levels is still unknown, especially among adolescents.

Objective:
The current study examines the differences in serum vitamin B9 and B12 in 360 girls and 369 boys smoking Cg, Wp, both (Cg+Wp), versus none.

Methods:
Self-reported smoking status and serum B9 and B12 were measured after obtaining assent and consent from all adolescents.

Results:
About 18.9% and 50.8% of the adolescents were B9 and B12 deficient. Levels of B9 (p<0.03) were greater in the boys while B12 was greater (p<0.0001) in the girls. The ANCOVA shows a main effect (p<0.004) of smoking status for B9. Further subgroup comparisons revealed lower B9 in the Cg+Wp group versus none (p<0.005), Cg only (p<0.05), and Wp only (p<0.001) groups, without differences (p>0.05) between none, Cg only, and Wp only groups. Likewise, the ANCOVA demonstrated a main effect (p<0.009) of smoking status for B12. Subsequent post hoc analysis shows lower B12 in the Cg+Wp group versus none (p<0.04), Cg only (p<0.007), and Wp only (p<0.007) groups, without differences (p>0.05) between none, Cg only, and Wp only groups.

Conclusions:
The results are unique and suggest that combining Cg with Wp smoking is associated with altered serum B9 and B12 levels. Therefore, programs are needed to implement plans and strategies to restrain the rapid spread of Cg and Wp smoking and to mitigate the negative effects of Cg and Wp smoking, especially among adolescents. Additionally, studies are warranted to verify the current results.