Study links plant-rich diets to improved odor detection in adults

Eating habits may influence how well a person detects odors, according to recent research involving nearly 6,700 adults. The investigation explores the connection between specific dietary patterns and the capacity to identify smells, offering insights into how nutrition interacts with sensory health.

Olfactory dysfunction prevalence

Poor smell detection correlates with reduced quality of life and malnutrition risks. Emerging evidence suggests that olfactory dysfunction also links to higher all-cause mortality among older populations. Approximately 22% of people experience some degree of smell impairment, often stemming from sinonasal disease, traumatic brain injury, or upper respiratory tract infections.

Diet significantly impacts chronic conditions, including neurological, cardiovascular, and metabolic diseases. Animal models indicate that unhealthy diets reduce olfactory discrimination and damage sensory neurons. In human contexts, Western diets high in sugar and fat have been tied to poorer odor identification and fat discrimination abilities.

CHRIS study methodology

Researchers utilized cross-sectional data from the Cooperative Health Research in South Tyrol (CHRIS) study, which tracks nearly 13,400 adults in Italy. For this analysis, they focused on 6,690 participants who completed lifestyle questionnaires and provided biological samples. Olfactory function was measured using the 16-item Sniffin’ Sticks test, where identifying 12 or fewer odors classified individuals as having hyposmia.

Dietary intake was evaluated via a food frequency questionnaire covering mean consumption over the past year. The team calculated several indices: the Mediterranean diet index (MED), Alternate Healthy Eating Index 2010 (AHEI), and overall, healthful, and unhealthful plant-based diet indices (PDI, hPDI, uPDI). Statistical models adjusted for factors such as sex, age, education, BMI, smoking, hypertension, and total energy intake.

Dietary adherence outcomes

The study cohort had a mean age of 44.5 years, with 54% female participants and 55% non-smokers. Those in the highest olfactory function quartile tended to be younger, female, and had lower BMI and alcohol intake compared to those in the lowest quartile. While these individuals showed marginally better AHEI adherence, their hPDI scores were lower.

Greater adherence to healthier patterns—assessed by AHEI, MED, PDI, and hPDI—correlated modestly with higher odds of belonging to a better olfactory category. Odds ratios per standard-deviation increase were 1.09 for AHEI, 1.06 for MED, 1.05 for PDI, and 1.07 for hPDI. Conversely, an inverse association existed between uPDI and olfaction. Higher fruit and vegetable consumption, along with reported tea, coffee, or alcoholic beverage intake, aligned with better odor identification.

Hyposmia risk factors

Higher scores on all dietary indices except uPDI associated with lower odds of hyposmia. The opposite trend appeared for uPDI. Hyposmia likelihood decreased with increased fruit and vegetable intake and among consumers of coffee, tea, wine, or beer versus non-consumers. Authors noted these associations do not imply alcohol improves smell, citing guidelines that no level of alcohol is safe.

Sensitivity analyses adjusting for Parkinson’s disease screening and cognitive impairment yielded results similar to primary findings, though PDI and MED associations with olfactory function, and hPDI with hyposmia, lost significance. Overall, the data suggest that adhering to healthy, plant-rich diets lowers hyposmia risk and enhances odor identification, while unhealthful plant-based patterns correspond with worse olfactory outcomes.