Folate (B9)

What is vitamin B9?

Vitamin B9, also known as folate, is an essential nutrient that helps our cells develop and function properly. It is a water-soluble vitamin, which means it is not stored in the body in large amounts. While the term folate is often used interchangeably with folic acid, these are technically not the same. They are both forms of the same vitamin (vitamin B9), but folate is the form naturally found in food, and folic acid is the form found in supplements.¹ Folic acid is more easily absorbed in the body, but either form can be used to meet our vitamin B9 needs.²

Why we need it

Folate helps our bodies synthesize DNA, a molecule that carries our genetic information. For instance, enzymes that produce purine and pyrimidine (compounds that make up DNA) require folate to function.² Similarly, folate is involved in methylating DNA (a process in which methyl groups are transferred to DNA molecules), thereby helping to regulate gene expression.² Folate is also involved in repairing damaged DNA, which may help protect against cancer and other diseases associated with DNA damage.³

Additionally, folate plays a role in the metabolism of amino acids (the building blocks of protein). For instance, folate is essential for converting the homocysteine to methionine,2 which is important for various reasons. First off, the amino acid homocysteine is linked to various negative health outcomes, including an increased risk of heart disease and neurodegenerative diseases.⁴ Further, the amino acid methionine is needed to produce S-adenosyl methionine (SAM), which is a compound that regulates gene expression and hormone production, and helps us clear out harmful materials from our cells.⁵

Where it’s found

Folate is naturally found in many foods, mainly vegetables (hence its name, which originates from the Latin word folium, which means “leaf”), as well as fruits and legumes. Folate is also added to breads and cereals through a process called fortification. Specific examples of folate-rich foods include:

Spinach
Broccoli
Brussels sprouts
Beans and lentils
Nuts
Bananas
Oranges
Cereals, breads, and grains

You can also get vitamin B9 in the form of folic acid from dietary supplements. These include supplements containing only folic acid, as well as some multivitamins, prenatal vitamins, and B complex supplements.⁶

Daily requirements

The daily Recommended Dietary Allowance (RDA) for folate (i.e. the amount that is likely to meet the needs of most healthy people) is 65-80 micrograms (μg) for infants, 150 μg for children aged 1-3 years, 200 μg for children aged 4-8 years, 300 μg for children aged 9-13 years, and 400 μg for individuals aged 14 years and over.¹ For women who are pregnant or breastfeeding, the RDA increases to 600 μg and 500 μg, respectively.¹

These RDA values are expressed as μg of dietary folate equivalents (DFEs), which is a standardized measure that accounts for the different forms of folate (i.e., folate from food and folic acid from supplements).¹

Folate deficiency

Folate deficiency can have a wide range of health consequences. It can cause megaloblastic anemia, a condition in which red blood cells fail to mature and become abnormally large in size.² Symptoms of megaloblastic anemia include fatigue, weakness, irritability, difficulty concentrating, and swelling of the tongue.¹

Folate deficiency can also impair growth and development. For example, folate deficiency may lead to neural tube defects (NTDs), which are a type of birth defect that can affect the spine, skull, or brain.⁶ Preventing NTDs is partly why getting enough folate is so critical during pregnancy, and why the RDA for folate is higher for pregnant women.

Folate deficiency is also associated with an increased risk for chronic diseases such as heart disease.² This may be in part due to elevated levels of homocysteine in the blood.²

Most people get enough folate through their diet, so deficiency is relatively rare.⁶ Nonetheless, folate deficiency does still occur, and is more common among certain groups of people. Groups that may be at a higher risk include people with alcoholism (since alcohol may reduce folate absorption and increase folate breakdown), pregnant women (due to increased folate requirements), and people with malabsorptive disorders like inflammatory bowel disease or celiac disease (which may interfere with folate absorption).⁶

Can you get too much folate?

To prevent toxicity, a Tolerable Upper Intake Level (UL) has been established for folate. The UL for folate, or the maximum amount that is considered safe, is 300 μg for children aged 1-3 years, 400 μg for children aged 4-8 years, 600 μg for children aged 9-13 years, 800 μg for adolescents aged 14-18 years, and 1,000 μg for adults over the age of 19 years.¹

Fun facts

Cereal and grain products are actually required to be fortified with folate. This mandate has been in place since 1998, with the goal of preventing NTDs.⁷

Folate is closely related to another B vitamin called cobalamin (or vitamin B12). The two work together to carry out many of the same functions, and they share similar signs of deficiency.¹ In fact, consuming excess amounts of folate may mask vitamin B12 deficiency, which is part of the reason that a Tolerable Upper Intake Level was established for folate.¹