In a 2011 large-scale study published in Laterality, researchers analyzed more than 1 million participants to determine whether or not a link existed between left-handedness and three specific health conditions: allergies, ulcers, and arthritis. No relationship was observed between left-handedness and allergies. When it came to ulcers and arthritis, however, a connection was seen between left-handedness and lower rates of both conditions. Because genetics is thought to play a role in hand dominance, the study team theorized that these same genes may potentially be involved in the relationship between left-handedness and reduced rates of ulcers and arthritis.
Another theory was explored in the previously mentioned 2016 study published in Scientific Reports, in which greater joint involvement was seen in right-hand dominant rheumatoid arthritis patients compared to joints on their non-dominant side (in this case, the left). More significant joint destruction due to erosion was also seen on the participants’ dominant side, indicating that the increased involvement of these joints may be partially responsible. Although this same relationship existed between left-hand dominant RA patients and greater joint involvement, it was not deemed statistically significant. Because the study had a number of limitations, however, no definitive conclusions can be drawn. Only 4% of subjects included in the research were left-handed. Therefore, future studies with a larger sample size are still needed.