Isothiocyanates are detected in human synovial fluid following broccoli consumption and can affect the tissues of the knee joint

Davidson R, Gardner S, Jupp O, Bullough A, Butters S, Watts L, Donell S, Traka M, Saha S, Mithen R, Peffers M, Clegg P, Bao Y, Cassidy A, Clark I · Scientific Reports

Tests delivery directly, in synovial fluid: isothiocyanates were present in the synovial fluid of the high-glucosinolate group (mean 497 nM) and absent in the low group, mirrored by higher plasma isothiocyanates and sulforaphane specifically. Proteomic analysis of the synovial fluid separated the two groups, with 125 differentially expressed proteins. Beyond arrival, every functional readout was null: cartilage explants from the two groups degraded at the same rate in culture, plasma hsCRP and the collagen fragment Coll2-1 did not move, five synovial cytokines did not differ, and cartilage and fat gene expression showed no difference after adjustment for multiple testing. The high-glucosinolate group also ate significantly more vitamin C, which the authors say they cannot rule out. They describe the trial as proof-of-principle and say the functional test comes next.

Population

Adults with knee osteoarthritis awaiting total knee replacement

Intervention

High-glucosinolate diet for 14 days before surgery

Comparator

Low-glucosinolate diet

Limitations

Fourteen days, 40 randomised and 37 analysed, and it measures arrival rather than benefit: nothing here says a knee did better. Proteomics ran on 17 of the fluids. The high-glucoraphanin broccoli is patented by Plant Bioscience Limited with a named inventor among the authors, and licensed to a seed company; the paper discloses this. Funded by the BBSRC's Diet and Health Research Industry Club and Action Arthritis.