All subjects were healthy, had normal concentrations of folate and vitamin B12, and did not consume food fortified with folic acid or take B-vitamin supplements before or during the 26-week study.

• 在研究之前或在为期26周的研究中，不食用强化了叶酸或维生素B12的增补剂，研究结果证明，所有的研究对象都是健康的，并且血浆叶酸和维生素B12的浓度都是正常的。