Olfaction and Changes in Body Composition in a Large Cohort of Older U.S. Adults

Poor sense of smell in older adults may lead to weight loss, which may further contribute to various adverse health outcomes. However, empirical prospective evidence is lacking. We aimed to longitudinally assess whether poor olfaction is associated with changes in body composition among older adults.

A total of 2,390 participants from the Health ABC Study had their olfaction assessed using the Brief Smell Identification Test in 1999-2000. Based on the test score, olfaction was defined as poor (0-8), moderate (9-10), or good (11-12). Total body mass, lean mass, and fat mass were measured by dual-energy X-ray absorptiometry annually or biennially from 1999 to 2007.

At baseline, compared to participants with good olfaction, those with poor olfaction weighed on average 1.67 kg less (95% CI: -2.92, -0.42) in total mass, 0.53 kg less (95% CI: -1.08, 0.02) in lean mass, and 1.14 kg less (95% CI: -1.96, -0.31) in fat mass. In longitudinal analyses, compared to participants with good olfaction, those with poor olfaction had a greater annual decline in both total mass (-234 g, 95% CI: -442, -26) and lean mass (-139 g, 95% CI: -236, -43). They also tended to have a greater annual loss of fat mass (-113 g, 95% CI: -285, 59), but the difference was not statistically significant.

Our results indicate poor olfaction is associated with lower body weight and greater weight loss in older adults. It is imperative for future studies to investigate potential underlying mechanisms and associated adverse health consequences.