Does tobacco use influence bone mineral density levels in a Norwegian youth cohort followed from adolescence to young adulthood? The Fit Futures Study (2010-2022).

OBJECTIVES

To investigate the longitudinal associations between tobacco use (smoking and snuff) and bone mineral density (BMD) at femoral sites and in the total body in a Norwegian adolescent cohort, aged 16-27 years.

DESIGN

Prospective longitudinal cohort study.

SETTING

A population-based study in Norwegian adolescents from the general population.

PARTICIPANTS

In total, 722 adolescents (385 females and 337 males) with a mean age of 16 years (SD: 0.5) from the Fit Futures Study (FF) were included at FF1 (2010-2011), with follow-up measures at age 18 years (FF2 (2012-2013)) and 27 years (FF3 (2021-2022)). Inclusion criteria were completed dual-energy X-ray absorptiometry (DXA) scans, serum vitamin D blood samples and information on smoking, snuff use, physical activity, height, alcohol intake, hormonal contraceptive use and puberty status, all at baseline (FF1).

PRIMARY AND SECONDARY OUTCOME MEASURES

Associations between self-reported smoking and snuff use (categorised as never, sometimes or daily) and changes in BMD (g/cm²) at the total hip, femoral neck and total body, measured using DXA.

RESULTS

Total hip BMD (mean (g/cm), 95% CI) slightly increased from FF1 (females: 1.066, 95% CI 1.054 to 1.079; males: 1.121, 95% CI 1.105 to 1.136) to FF2 (females: 1.076, 95% CI 1.063 to 1.089; males: 1.141, 95% CI 1.126 to 1.157; p<0.001), but thereafter decreased to FF3 (females: 1.050, 95% CI 1.036 to 1.063; males: 1.091, 95% CI 1.074 to 1.107; females and males, both p<0.001). Similar patterns were observed for the femoral neck, while total body BMD increased from FF1 through FF3 (p<0.001). We observed interactions between time and smoking and between time and snuff use in all models (all p<0.001). However, we generally observed no statistically significant differences in BMD levels across smoking and snuff use groups at different time points (all p>0.07), except in females at 18 years (FF2), where those who never smoked had higher total hip BMD than those who sometimes and never smoked (p<0.001).

CONCLUSIONS

We found no statistically significant associations between smoking or snuff use and BMD levels in Norwegian adolescents from a median age of 16 to 27 years. Notably, only 2.6% of females and 3.9% of males reported smoking daily. However, in this study, moderate tobacco use did not appear to negatively influence bone growth from adolescence to young adulthood.