Keep in mind that the Centers for Disease Control and Prevention (CDC) recommends that all adults take 400 micrograms of folic acid daily. From the January 21, 2014 Science Daily:
Folic acid supplements at levels consumed by breast cancer patients and survivors in North America promoted the growth of existing breast cancer in rats, new research found.
The role of folate, a B vitamin, and its synthetic form, folic acid, in the development and progression of breast cancer is highly controversial. Although some studies have found it may offer protection against breast cancer, recent studies have suggested that taking high amounts of folic acid may increase the risk of developing breast cancer.
Dr. Young-In Kim, a physician and researcher at St. Michael's Hospital, said his lab has shown for the first time that folic acid supplements in doses 2.5 to five times the daily requirement "significantly promotes" the growth of existing pre-cancerous or cancerous cells in the mammary glands of rats.
This is a critically important issue because breast cancer patients and survivors in North America are exposed to high levels of folic acid through folic acid fortification in food and widespread use of vitamin supplements after a cancer diagnosis," Dr. Kim said. "Cancer patients and survivors in North America have a high prevalence of multivitamin and supplement use, with breast cancer patients and survivors having the highest prevalence."