[Etiological study of spinal ligament ossification with special reference to dietary habits and serum sex hormones].

We studied the relationship between dietary habits and the ossification of the posterior longitudinal ligaments (OPLL) in 55 patients. We analyzed carbon and nitrogen isotope ratios of the patients' hair in order to measure the intake of various types of food. Two sets of questionnaire on the patients' food preference and the intake are also analyzed. The patients showed a tendency to prefer vegetable protein to animal protein, in comparison with the control. In 23 OPLL male patients, level of the estrogen in the serum was higher than in the control. The results suggest that the dietary habits of OPLL patients and the sex hormone imbalance are responsible for the development of OPLL.