Folic Acid: Why 400 Micrograms a Day Matters Before and During Pregnancy

Image from CDC's page about folic acid

Folic acid is a form of folate (vitamin B9), which the body needs to make new cells — blood cells, brain cells, skin, hair and nails. Every new cell needs folate.

All women who could become pregnant should get 400 micrograms (mcg) of folic acid every day.

Why: neural tube defects

In early pregnancy, folic acid helps the neural tube — which becomes the brain and spine — develop. It is the only form of folate shown in studies to help prevent serious birth defects called neural tube defects (NTDs) of the brain, such as anencephaly, and of the spine, such as spina bifida.

NTDs form in the first few weeks of pregnancy, often before you know you're pregnant — by then it may be too late. That's why folic acid matters before and during early pregnancy, and why the daily habit matters even if you're not planning a pregnancy.

Folate or folic acid?

The words are often used interchangeably, but folate covers all forms of vitamin B9: the natural folates in foods such as leafy greens and beans, and made forms including dihydrofolate (DHF), tetrahydrofolate (THF), 5,10-methylenetetrahydrofolate, 5-methyltetrahydrofolate (5-MTHF) and folic acid. Folic acid is the form in supplements and fortified foods such as breakfast cereals — and the only one shown to help prevent NTDs. More: sources and recommended intake.

The recommendations

The evidence

• Since 1965, studies have linked low blood folate to a higher risk of NTDs.
• In the 1990s, two large randomized controlled trials showed that vitamins with folic acid lower that risk — one in women who'd already had an NTD-affected pregnancy, the other in women who hadn't. In both, folic acid before and during early pregnancy reduced the chance of an affected baby.
• Further studies examined how daily folic acid raises blood folate, when it helps, and how adding it to foods changed how often NTDs occur. Together they support the 400 mcg recommendation. CDC's short documentary The Story of Folic Acid Fortification tells the story of fortification in the United States.

What you can do

• Start the habit: 400 mcg a day, even if you're not planning a pregnancy.
• Plan ahead: if you're thinking about pregnancy, start at least 1 month before conception and continue during pregnancy.
• Check labels on vitamins and fortified foods for folic acid.
• Eat folate-rich foods such as leafy greens, beans and oranges.
• Ask your doctor any questions.

Sources

Based on "About Folic Acid," Centers for Disease Control and Prevention; a work of the United States government in the public domain. A posed photograph from the page is not reproduced.