The present cross-sectional study, based on nationally representative data, did not find a significant association between smoking and the presence of anemia. However, it was identified that the age of 30 to 49 years was associated with a higher prevalence of anemia, while the factors associated with a lower prevalence of anemia were black ethnicity, overweight, obesity, and living in small cities.
The absence of a significant association between smoking and anemia coincides with the heterogeneity reported in the literature. A previous case-control study conducted in India found that tobacco smoking was strongly associated with anemia (OR: 7.72, p < 0.001) [7]. Likewise, another cross-sectional study conducted in Ghana found that hemoglobin levels were significantly lower in those who smoked almost daily (β: −1.40; 95% CI: −2.01 to −0.79), at least once a month (β: −1.14; 95% CI: −1.79 to −0.48) or were exposed to secondhand smoke (β: −0.77; 95% CI: −1.30 to −0.21) [8]. Similarly, another study conducted in an older adult population in India found that the odds of anemia were higher in those with a history of tobacco abuse (aOR: 1.23; 95% CI: 1.12 to 1.35) [11]. On the other hand, a study conducted in Bosnia and Herzegovina revealed that smokers had significantly higher levels of hemoglobin (14.7 vs. 13.9 g/dL, p = 0.042) [9]. Finally, a study conducted in the United States found that in both women and men, smokers had significantly higher average hemoglobin levels than non-smokers [10].
From a pathophysiological point of view, these differences could be due to the fact that smoking can decrease hemoglobin levels due to mechanisms such as interference with iron and vitamin absorption, oxidative stress, and increased concurrent chronic diseases [5]. In contrast, it has been proposed that smoking may raise hemoglobin levels due to chronic hypoxia induced by carboxyhemoglobin formation following exposure to carbon monoxide from cigarette smoke, resulting in a compensatory response that is not necessarily beneficial, as it may favor a state of hypercoagulability [15, 16].
In addition, differences in the characteristics of the populations studied, levels of exposure to tobacco, the type of products smoked, exposure to other types of biomasses, nutritional status and the presence of underlying inflammatory or infectious conditions must be considered. Also, it is important to take into account that the results were consistent between smoking the last 12 months, the last 30 days and smoking daily, which reinforces the robustness of our conclusions.
Regarding other variables associated with anemia, it was observed that women between 30 and 49 years of age had a higher prevalence of anemia compared to younger women, a finding that is consistent with previous studies [17]. On the other hand, black ethnicity was associated with a lower prevalence of anemia, a finding discordant with previous literature [18], probably because there are contextual factors specific to Peru, such as differences in access to health services, dietary patterns, or biases in self-reported ethnic classification, which could have influenced this result. Another interesting finding was that overweight and obesity were associated with lower prevalence of anemia, which coincides with previous studies suggesting that excess weight may be related to higher iron and vitamin C intake [19].
Implications and recommendations
These findings provide relevant local evidence that could guide future anemia prevention strategies in adult women. Although no association was found, smoking remains a leading modifiable risk factor for multiple chronic conditions and continues to impose a high economic and disease burden in Peru. As highlighted by national estimates, smoking is responsible for over 22,000 deaths and 126,000 disease events annually, with a substantial loss in productivity and health system costs [13]. Therefore, tobacco control policies should be sustained and strengthened, not only for their established benefits in reducing cardiovascular, respiratory, and cancer outcomes, but also to ensure comprehensive health protection. Importantly, these findings are specific to women and should not be extrapolated to men, where tobacco use is more prevalent and the potential impact on hematological outcomes may differ [20]. In addition, the findings highlight the importance of considering nutritional status, ethnicity, and age when designing interventions to reduce the burden of anemia in women of reproductive age.
Future research directions
It is recommended that future studies be longitudinal to better understand how smoking influences anemia risk. Moreover, it would be relevant to evaluate the intensity, duration and type of tobacco consumption. Also, future research should explore how anemia is affected by secondhand smoke exposure, particularly in household and occupational settings, as well as exposure to indoor air pollution from biomass fuels such as wood or charcoal, which remain common sources of energy in many regions of Peru.
Limitations and strengths
The present study has several limitations. Firstly, the cross-sectional design prevents establishing temporality. Analyses could not be performed according to the intensity, duration and type of tobacco use. However, in this study we used a national database representative of the Peruvian population that includes the main sociodemographic and clinical covariates to perform an appropriate adjusted analysis.