Relationship Between "Geosminophilia" (Liking the Smell of Earth) and Pica in Patients With Iron Deficiency

Abstract

Background: Iron deficiency is a critical global health issue. One of the intriguing manifestations linked to iron deficiency is the presence of pica. The physiological relationship between the senses of smell and taste suggests that pica may be accompanied by an inclination towards the smell of earth (geosmin). The smell of geosmin is distinct and generally recognized as a pleasing scent. The objective of this study is to explore this potential association. The sign of liking the smell of earth will now be referred to as "geosminophilia", for the first time, in this study.

Methods: Patients aged 18 years and above who visited the Iron Deficiency Outpatient Clinic between September 2021 and August 2022 were chosen for this cross-sectional study. The dataset excluded those with ferritin concentrations over 100 mcg/L and transferrin saturation over 45%. Demographics, presence of pica, history of geosminophilia, and laboratory findings were documented in physical and digital patient data. The descriptive statistics, chi-square test, and independent group comparison tests were performed.

Results: With a mean age of 38.7±11.7 years, the study sample comprised 280 patients, of which 263 were female and 17 were male. Ninety-six patients (34.3%) had geosminophilia, while 29 patients (10.4%) had pica. The only factors that significantly distinguished the groups based on the presence of geosminophilia were gender (p=0.04) and age (p=0.02). Using the chi-square test to compare the presence of pica and geosminophilia, a statistically significant relationship was identified (p<0.001). Additionally, 72.4% of patients who presented with pica had geosminophilia. Pica was absent in 96% of patients who did not have geosminophilia. A total of 93.8% (15/16) of pica cases with geophagia subtype exhibited the presence of geosminophilia. A significant correlation (r=0.27, p<0.001) was also observed between geosminophilia and pica.

Conclusion: In iron deficiency patients, geosminophilia and the presence of pica may accompany each other. Therefore, geosminophilia has the potential to be a new symptom of iron deficiency.

Keywords: geosmin; geosminophilia; iron deficiency; olfactory signs; pica; smell of earth; symptom.