Lower serum levels of alpha tocopherol and lycopene are associated with higher pain and physical disability in subjects with primary knee osteoarthritis: A case-control study.

Abstract

Background: We aimed to determine dietary intake and serum concentration of α-tocopherol and lycopene in subjects with knee osteoarthritis (KOA) in relation to pain intensity and functional status and comparing them with healthy controls. Methods: This case-control study was conducted among 35 patients with primary KOA and 35 matched healthy subjects selected using convenience sampling method. Dietary intakes of alpha-tocopherol and lycopene were estimated from 24-hour dietary records. Visual Analogue Scale (VAS) and Western Ontario and McMaster (WOMAC) index were used to assess the pain and functional status, respectively. Results: Serum concentrations of alpha-tocopherol (0.024±0.005 vs. 0.028±0.007μmol/ml, p-value= 0.021) and lycopene (0.616±0.191 vs. 0.727±0.159μmol/l, p-value=0.011) were significantly lower in OA patients in comparison with healthy controls. Dietary intake of alpha-tocopherol was negatively associated with total WOMAC score (r=-0.401, p-value=0.021) and pain (r=-0.356, p-value=0.042) and physical function (r=-0.355, p-value=0.043) subscales. Dietary intake of lycopene was negatively associated with total WOMAC score (r=-0.616, p-value<0.001) and pain (r=-0.348, p-value=0.047) and physical function (r=-0.606, p-value<0.001) subscales. Additionally, serum concentration of alpha-tocopherol was negatively associated with total WOMAC score (r=-0.574, p-value<0.001) and physical function subscale (r=-0.571, p-value<0.001). Serum concentration of lycopene was negatively associated with total WOMAC score (r=-0.360, p-value=0.040) and physical function subscale (r=-0.350, p-value=0.046) Conclusion: Serum concentrations of α-tocopherol and lycopene were significantly lower in patients with KOA than in healthy controls. Significant negative association was detected between serum concentration and dietary intake of α-tocopherol and lycopene with functional disability in patients with KOA.