We performed additional analyses to further explore the effects of
potential confounders such as smoking, area of residence, -linolenic
acid in adipose tissue, intake of folate, alcohol, and vitamin B-6 by
stratifying the analyses by these variables. In these analyses, we used
unconditional logistic regression with matching variables in the
model and the other variables modeled as continuous covariates. We
computed the Hosmer-Lemeshow statistic to test for goodness of fit.