This question is asked a lot, especially by pregnant mamas. So let's break it down!
Folate and folic acid are different forms of vitamin B9.
Per Chris Kresser, "Folate is a general term for a group of water soluble b-vitamins, and is also known as B9. Folic acid refers to the oxidized synthetic compound used in dietary supplements and food fortification, whereas folate refers to the various tetrahydrofolate derivatives naturally found in food." (Source)
While there’s a distinct difference between the two, their names are often used interchangeably.
Folate is the naturally occurring form of vitamin B9. Its name is derived from the Latin word “folium,” which means leaf. In fact, leafy vegetables are among the best dietary sources of folate.
Folic acid is a synthetic form of vitamin B9, also known as pteroylmonoglutamic acid. It’s used in supplements and added to processed food products, such as flour and breakfast cereals.
Unlike folate, not all of the folic acid you consume is converted into the active form of vitamin B9 — 5-MTHF — in your digestive system - as a result, unmetabolized folic acid is commonly detected in people’s bloodstreams, even in the fasted state.
Kresser explains further, "The natural form can enter the main folate metabolic cycle is tetrahydrofolate (THF). Unlike natural folates, which are metabolized to THF in the mucosa of the small intestine, folic acid undergoes initial reduction and methylation in the liver, where conversion to the THF form requires dihydrofolate reductase. The low activity of this enzyme in the human liver, combined with a high intake of folic acid, may result in unnatural levels of unmetabolized folic acid entering the systemic circulation."
Several studies indicate that chronically elevated levels of unmetabolized folic acid may have adverse health effects, including:
Increased cancer risk. High levels of unmetabolized folic acid have been associated with increased cancer risk. However, no evidence proves that unmetabolized folic acid plays a direct role
Undetected B12 deficiency. Among elderly people, high folic acid levels can mask vitamin B12 deficiency. Untreated vitamin B12 deficiency may increase your risk of dementia and impair nerve function
The History of Folic Acid:
Folic acid was first synthesized in the 1940s and was initially used to treat megaloblastic anemia caused by folate deficiency. Its use became widespread in the 1960s.
Compared to natural folate, folic acid was less expensive and more chemically stable, making it ideal for supplements.
In the United States, the FDA requires food manufacturers to add 140 mcg of folic acid to every 100 grams of “enriched” grain products - In the US, most white bread, baked goods, cornmeal, white rice, white pasta, and refined breakfast cereals are enriched with folic acid.
MTHFR and Folic Acid:
30% to 60% of the US population has a genetic polymorphism called MTHFR. This is a genetic deficiency that limits the bodies ability to convert folate into the active form utilized by the body. (Source)
Mutations in the MTHFR gene causes less efficiency in converting folate to its active form, which in turn may lead to elevated levels of homocysteine. Maintaining appropriate levels of homocysteine is important in the prevention of chronic disease.
Individuals with MTHFR mutations have Methylation insufficiencies and impaired detoxification metabolism. The Methylation pathway is crucial for the production of Glutathione -- The Body’s Master Anti-Oxidant.
MTHFR is responsible for the last step in the activation of folate (converting 5,10-MTHF to L-5-MTHF)
Mutations in the genes that code for MTHFR are fairly common and can impair this conversion.
With the C677T mutation, the activity of MTHFR can be impaired by 35% in those who are heterozygous (one copy of the mutation) and up to 70% in those who are homozygous (two copies of the mutation).
When MTHFR activity is impaired, folic acid can’t be activated as quickly, leading to higher levels of unmetabolized folic acid and lower levels of active folate in the blood.