Causal relationship between dried fruit intake and frozen shoulder: Two-sample Mendelian randomization

To investigate the causal relationship between dried fruit intake and frozen shoulder using Mendelian randomization (MR). Genome wide association studies were conducted to pool data and select genetic loci independently associated with dried fruit intake and frozen shoulder in people of European ancestry as instrumental variables. Three MR analyses, inverse variance weighting, weighted median and MR-Egger, were used to investigate the causal relationship between dried fruit intake and frozen shoulder. Heterogeneity and multiplicity tests were used, and sensitivity analyses were conducted using the leave-one-out method to explore the robustness of the results. The inverse variance weighting results showed an OR (95 % CI) of 0.52 (0.34–0.80), P = .003, suggesting that there is a causal relationship between dried fruit intake and frozen shoulder. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results. The present study used a two-sample MR analysis, and by analyzing and exploring the genetic data, the study showed that too little intake of dry fruits is a risk factor for developing frozen shoulder.