Among 6,690 adults in the CHRIS cohort study, higher adherence to five established healthy dietary patterns — including the Mediterranean diet, Alternate Healthy Eating Index 2010, and the Healthy Plant-Based Dietary Index — was independently associated with better olfactory identification scores and lower odds of hyposmia (smell impairment, defined as scoring ≤12/16 on the Sniffin' Sticks test). Conversely, an unhealthy plant-based diet showed the opposite relationship. At the food-group level, fruits, vegetables, coffee, and tea drove the strongest benefits.
Olfactory dysfunction matters far beyond the dinner table: it predicts increased all-cause mortality in older adults, precedes neurodegeneration in Parkinson's and Alzheimer's disease, and reduces appetite and dietary quality — creating a potential vicious cycle. This study is one of the largest population-based analyses linking diet quality to olfaction, lending meaningful statistical power to its findings. The polyphenol, antioxidant, and anti-inflammatory constituents abundant in plant-rich diets plausibly protect olfactory receptor neurons and their central projections, though the mechanisms remain speculative here.
Critical caveats: the cross-sectional design prevents causal inference — poor smell may alter food choices rather than the reverse. Self-reported dietary intake carries well-known measurement error. Nonetheless, the consistency across five distinct dietary indices strengthens confidence. For adults concerned with cognitive aging and longevity, this adds another dimension to the already-robust case for plant-forward eating — one that can be meaningfully raised with a physician.