Dietary vitamin C intake and changes in frequency, severity, and location of pain in older adults.

BACKGROUND: Oral vitamin C supplementation has been associated with lower risk of chronic postsurgical pain. However, the effect of dietary vitamin C on pain in a non-surgical setting is unknown. We aimed to investigate the association between dietary vitamin C intake and changes over time in chronic pain and its characteristics in community-dwelling adults aged 60+ years.

METHODS: We pooled data from participants of the Seniors-ENRICA-1 (n=864) and Seniors-ENRICA-2 (n=862) cohorts who reported pain at baseline or at follow-up. Habitual diet was assessed with a face-to-face diet history and dietary vitamin C intake was estimated using standard food composition tables. Pain changes over time were the difference between scores at baseline and follow-up obtained from a pain scale that considered the frequency, severity, and number of pain locations. Multivariable-adjusted relative risk ratios (RRR) were obtained using multinomial logistic regression.

RESULTS: After a median follow-up of 2.6 years, pain worsened for 696 (40.3%) participants, improved for 734 (42.5%), and did not change for 296 (17.2%). Compared to the lowest tertile of energy-adjusted vitamin C intake, those in the highest tertile had a higher likelihood of overall pain improvement (RRR 1.61 [95% confidence interval 1.07-2.41],p-trend 0.02). Higher vitamin C intake was also associated with lower pain frequency (1.57 [1.00-2.47],p-trend=0.05) and number of pain locations (1.75 [1.13-2.70],p-trend=0.01).

CONCLUSIONS: Higher dietary vitamin C intake was associated with improvement of pain and with lower pain frequency and number of pain locations in older adults. Nutritional interventions to increase dietary vitamin C intake with the aim of improving pain management require clinical testing.