Aging is often accompanied by significant loss in the sense of smell, olfaction. Around 25% of persons aged 60 years and above suffer from olfactory impairment (OI), and prevalence rates increase substantially with age. Still, potentially harmful consequences of smell loss are poorly understood. Although some previous studies have linked OI to depression, low quality of life, poor appetite, and malnutrition, these studies have mainly been based on cross-sectional designs and clinical samples, precluding causal interpretations and generalizations to the population. Smell loss has also been associated with a shorter life span, although without information about cause of death, the underlying mechanisms remain speculative. Based on comprehensive data from two Swedish large-scale population-based longitudinal studies, including standardized measures of olfactory function, we will focus on (1) the longitudinal association between OI and commonly associated conditions such as depression, loneliness, and malnutrition, (2) modifying factors of developing harmful consequences of OI, such as for example demographic and health variables, and (3) why OI would be associated with a shorter lifespan, factoring in cause of death.