. . . "B vitamins such as folate and vitamin B6 play an important role in DNA methylation,2,3 and molecular studies show that ER-negative breast cancer is caused by the lack of ER gene transcription due to the methylation of the CpG island 5??? to the gene.39 Likewise, previous epidemiologic studies have shown an elevated risk of ER-negative tumors among women who had a low intake of folate.23,24 Our dat" . .