Harvard Women's Health Watch

Ask the doctor: Does folic acid improve immunity?

Q. What do you know about taking extra folic acid to boost the immune system?

A. Folic acid is the synthetic form of folate, a B vitamin that occurs naturally in some foods, including vegetables, fruits, and dried beans and peas — and is essential for health. Folate is vital for the production and maintenance of our bodies' cells, especially during rapid periods of growth, such as pregnancy and infancy. It's needed to make DNA and RNA, the genetic material that dictates cell functions, and it helps prevent changes to DNA that may lead to cancer.

Since folate helps make and repair DNA, it makes theoretical sense that a deficiency of the vitamin could hamper immunity. In some animal experiments, severe folate deficiency has been found to impair immunity, but this hasn't yet been shown in human studies, and even in animals, the health impact remains unclear. With regard to taking higher-than-recommended doses of folate or folic acid to prevent disease or improve overall health, the evidence from clinical trials is conflicting.

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