Does gastrectomy predispose to amyotrophic lateral sclerosis?

Some authors have suggested that amyotrophic lateral sclerosis (ALS) may be precipitated by a "deficiency factor" following gastrectomy. Methods to establish a statistical association of the disease with gastrectomy include a case-control study. Two such studies have been made in Japan, one involving 712 and the other 158 cases of the diseases. No statistically significant association between gastrectomy and the subsequent occurrence of ALS was found, indicating it is unlikely that the operation predisposes to ALS. None of many other factors studied except mechanical injury showed a statistically significant association in either study.