Folate: A Unique Member of the B Vitamin Family in Multiple Ways

One of the most common vitamin deficiencies in the United States?

By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital
Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily

Typically, it’s best to get vitamins from their natural food sources. For folate, though, this may not be the case. Professor Anding explains.

Folic Acid concept
In 1998, the U.S. Public Health Service and other organizations increased the level of folic acid that was added to food, which reduced the incidence of neural tube defects in infants. Photo By Ekaterina Markelova / Shutterstock

Functions and Sources of Folate

Folate, also called vitamin B9 or folic acid, is named for its primary food sources: foliage. When you’re thinking of food sources of folic acid, think green and leafy. 

Multiple forms of the vitamin exist. Folic acid is the most stable one, and it’s the form found in most fortified foods including breakfast cereal.

Thus, breakfast cereal is a great source of folic acid, but you wash off some of that water-soluble vitamin into the milk. If you discard the milk, you’ve discarded some of the folic acid—so be sure to drink the milk with your cereal.

Folate is needed for the metabolism of amino acids. It’s unique in the fact that it also plays a role in the synthesis of DNA. It also is absolutely critical for cell division—which will explain in part some of the medicines developed around this function.

Folic Acid, Pregnancy, and Cancer

Folate is also instrumental for the development of the neural tube that forms in the first six weeks of pregnancy. A neural tube develops before a woman might even know that she’s pregnant. Neural tube defects include the diseases spina bifida and anencephaly, where the infant is born without a portion of his or her brain. Since 50% of pregnancies are unplanned, all sexually active women of childbearing age should take a multivitamin containing folic acid.

“The unusual thing is we have a pretty high incidence of neural tube defects in south Texas; so Baylor College of Medicine did a study, taking a look at what it would take to keep individuals taking folic acid,” Professor Anding said. “The only way we could keep impoverished youth, with a high prevalence of neural tube defects, from omitting folic acid was to provide them a multivitamin. If we suggested that they buy a multivitamin, they weren’t going to do it. If we provided it, they would take it.” 

Anding’s team found that in the Hispanic population, the cultural influences on pregnancy prevention were not universal. Many women in their subject population believed that having a baby before the age of 20 was beneficial, and termination was not an option for them. 

“If they became pregnant and had a baby with spina bifida, we could have prevented that by giving them folic acid, provided they would take it,” Professor Anding said.

A Harvard nurses’ study suggested that women who took folate for over 15 years had a significant reduction in colon cancer. Other studies suggest that if the cancer is already present but undiagnosed, folate may actually fuel the fire, given its role in cell division. That is because if folic acid is needed for normal cell division and the cancer is already present, folic acid may help continue that cancer on its growth path. 


When it comes to the bioavailability of folate, the form is important. The body absorbs about 100% of folic acid in fortified foods and supplements if it’s on an empty stomach. So, this is a case where the folic acid that is sprayed on breakfast cereal is actually more biologically available than the folate in food. 

However, only 85% of folate is going to be absorbed if other foods are present in that meal. For example, suppose you have breakfast cereal in the morning along with scrambled eggs and some fruit. 

The more foods you add, the less bioavailable that folic acid on your breakfast cereal is. Only between 50% and around 67% of folate naturally occurring in foods is available. Although green leafy vegetables are a great source of folate, the bioavailability of folic acid in broccoli is not going to be as good as folic acid in breakfast cereal.

Folate is not stable and is extremely vulnerable to heat, which can destroy up to 90% of food folate. Thus, when you eat broccoli, you should, on occasion, eat your broccoli raw or mix a cooked vegetable with something else that’s both green and leafy. 

Iceberg lettuce, for example, is leafy but not necessarily green. Therefore, spinach and romaine are much better sources of food folate than iceberg lettuce.

“Folic acid or folate has a bodyguard in vitamin C, and vitamin C can actually aid in the protection of folate,” Professor Anding said.


Until recently, folate was one of the most common vitamin deficiencies in the United States. However, as a public health intervention in 1998, the U.S. Public Health Service, as well as other organizations, increased the level of folic acid that was added to food, which improved the blood levels of Americans and reduced the incidence of neural tube defects. 

Folate deficiency influences red blood cell development, resulting in blood cells that are often poorly formed. This type of anemia is called “microcytic.” 

Folate deficiency also impairs the synthesis of white blood cells and compromises the immune system. Any rapidly growing cell is quickly affected by folate deficiency, including cells in the GI tract and the mouth.

In fact, B vitamin deficiencies in general are manifested in the mouth. Symptoms include a swollen, red, beefy tongue. 

The deficiency of either folate or vitamin B12 produces anemia. Taking folate supplements can correct the anemia, regardless of the cause. This means that folic acid can actually mask a vitamin B12 deficiency because it corrects the type of anemia that’s formed.

Some prescription medicines may act as a folate antagonist, and therefore the deficiency is intentional. There are times when we want to halt cell division. 

Methotrexate works as a folic acid antagonist, and it’s used to treat ectopic pregnancies that are growing outside of the uterus—possibly in the fallopian tube—and rheumatoid arthritis, which is when inflammatory cells accumulate in joints. 

“The abnormal cell division can be corrected within 48 hours of taking adequate folate. So, I think the challenge here is that there are medications that specifically induce a folic acid deficiency because of its effect on cell division,” Professor Anding said.

Toxicity and Interactions

Scientists have not found any indications of folate toxicity. Again, though, you should be aware that large doses of folate can mask a B12 deficiency.

This concern actually delayed the increase in fortification in 1998, as there was an increased risk of B12 deficiency with aging. This means that the older we get, the more likely we are to have a B12 deficiency, and taking folate can actually mask or cover that up. 

Thus, when we enrich or fortify the food supply, for some individuals, that fortification may be harmful. Additionally, some individuals may have a hypersensitivity to folate.

In tomorrow’s article, you’ll learn more about Vitamin B12 deficiencies.

This article was edited by Kate Findley, Writer for Wondrium Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for Wondrium Daily.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.