What is folate (folic acid)?

In one line

Folate is a water-soluble B vitamin the body needs to make new cells, such as red blood cells, and DNA.

What is folate (folic acid)?
A name from pregnancy supplements and labels
You often see 'folate' or 'folic acid' on supplements taken before pregnancy and on multivitamin labels. This post explains what kind of vitamin folate is, what it does in the body, where it is found, and why it comes up even before pregnancy.
In one line
The vitamin needed to make new cells
Vitamins are nutrients the body needs in small amounts to grow and work properly. Folate is one of the B vitamins and is also called 'vitamin B9'. The body needs folate when it makes new cells.
A 'leaf' in the name
Named after green leafy vegetables
In Korean, folate is called 'yeop-san', and 'yeop' is the Chinese character for 'leaf'. As the name suggests, it is plentiful in dark green leafy vegetables such as spinach. Beans, citrus fruits such as oranges, and liver also contain it.
Folate and folic acid
The form added to supplements is man-made
The form found naturally in food is called 'folate'. The form made in factories and added to supplements or to 'fortified foods' (foods with vitamins deliberately added, such as cereals and bread) is called 'folic acid'. People often use the two words for the same thing.
A water-soluble vitamin
The body cannot store much of it
Folate is a 'water-soluble vitamin', so leftovers leave the body in urine. Because the body stores little of it, blood folate drops after only a few weeks of a low-folate diet. It is also easily destroyed by heat, so overcooking vegetables destroys it.
What it does
It makes red blood cells and DNA
Red blood cells are the cells in blood that carry oxygen. Folate is needed for red blood cells to form and grow. Folate is also used to make 'DNA', the body's blueprint found in every cell.
When you run low
Anemia with oversized red blood cells
'Anemia' is a state where there are too few red blood cells, so oxygen does not reach the body well. When folate runs low, the body makes red blood cells that are large but few, causing anemia. People tire easily, and the tongue becomes smooth and sore. Eating few vegetables and fruits or drinking a lot of alcohol makes shortage more likely.
Folate and pregnancy
Needed when the baby's brain and spinal cord form
The spinal cord is the thick bundle of nerves running inside the backbone. A birth defect in which a baby's brain or spinal cord does not form properly is called a 'neural tube defect'. In trials where women took folate daily around the time of conception, these defects fell to about 1/3.
How much a day
The adult recommendation is 400 micrograms
The US recommended amount for adults is 400 micrograms a day, and more during pregnancy. A microgram is one-thousandth of a milligram, a very small amount. The US Centers for Disease Control and Prevention advises women who could become pregnant to get 400 micrograms of folic acid daily on top of food.
Too much
It hides vitamin B12 shortage
The US daily upper limit for adults for folic acid from supplements and fortified foods is 1,000 micrograms. Large amounts of folic acid make the anemia caused by low vitamin B12 look better, so B12 shortage is noticed late. Meanwhile, the nerve damage caused by low B12 does not stop.
A common myth
Is it fine to start once you know you are pregnant?
Starting after learning of a pregnancy is often already too late. Neural tube defects happen in the first month of pregnancy, often before a woman even knows she is pregnant. That is why the US Centers for Disease Control and Prevention advises taking it daily from before pregnancy, and the trials that showed a benefit gave it around the time of conception.
Summary
The B vitamin that builds new cells
Folate is a water-soluble B vitamin the body needs to make new cells, such as red blood cells, and DNA. A baby's brain and spinal cord often form before the pregnancy is known, so starting folate only after learning of a pregnancy is often too late. Related terms: vitamin B12, anemia, neural tube defect.