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

Background: We aimed to determine dietary intake and serum concentration of alpha-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 +/- 0.007 mu mol/ml, p-value = 0.021) and lycopene (0.616 +/- 0.191 vs. 0.727 +/- 0.159 mu mol/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 alpha-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 alpha-tocopherol and lycopene with functional disability in patients with KOA.

Automated summary

This study found that serum concentrations of alpha-tocopherol and lycopene were significantly lower in patients with knee osteoarthritis compared to healthy controls. Additionally, there was a significant negative association between serum concentration and dietary intake of these nutrients with functional disability in patients with knee osteoarthritis.