Vitamin B9, also called folate or folacin is a water-soluble B-vitamin. Naturally occurring folates exist in many chemical forms:
- folates are found in food, as well as in metabolically active forms in the human body
- and folic acid, the major synthetic form found in fortified foods and vitamin supplements.
It aids in the production of DNA and RNA, the body’s genetic material, and is especially important when cells and tissues are growing rapidly, such as in infancy, adolescence, and pregnancy. Folic acid also works closely with vitamin B12 to help make red blood cells and help iron work properly in the body.
Vitamin B9 works with vitamins B6 and B12 and other nutrients to control blood levels of the amino acid homocysteine. High levels of homocysteine are associated with heart disease, however researchers are not sure whether homocysteine is a cause of heart disease or just a marker that indicates someone may have heart disease.
Folate is essential for brain development and function. Low folate status and/or high homocysteine concentrations are associated with cognitive dysfunction in aging (from mild impairments to dementia). Whether supplemental B-vitamins, including folic acid, will have long-term benefits in maintaining cognitive health is not yet known.
Since it has been identified, there have been many studies about folate function in human body. Some of them suggest that taking prenatal folic acid supplements at the time of conception is associated with a lower risk of autism. Other studies show that taking folic acid supplements in early pregnancy was associated with a reduced risk of severe language delay in children at age 3 years. And some research suggests that low folate levels during pregnancy is associated with a higher risk of emotional problems in the offspring.
Folate deficiency is most often caused by a dietary insufficiency but it can also occur in a number of other situations. For example:
- chronic and heavy alcohol consumption is associated with diminished absorption of folate (in addition to low dietary intake)
- smoking is also associated with low folate status.
- impaired folate transport to the fetus has been described in pregnant women who either smoked or abused alcohol during their pregnancy.
Pregnancy is a time when the folate requirement is greatly increased to sustain the demand for rapid cell replication and growth of fetal, placental, and maternal tissue. Pregnant women who do not get enough folic acid are more likely to have children with birth defects.
Folic acid deficiency can cause:
- Poor growth
- Tongue inflammation
- Loss of appetite
- Shortness of breath
- Mental sluggishness
Food sources of folate
As the name implies, green leafy vegetables (or foliage) are among the best sources of folate. Citrus fruit juices, legumes, and fortified foods are also excellent sources of folatete content of fortified cereal varies greatly. A number of folate-rich foods are listed in the next table, along with their folate content in micrograms (μg).
|Food||Serving||Folate (μg DFEs)|
|Lentils (mature seeds, cooked, boiled)||½ cup||179|
|Garbanzo beans (chickpeas, cooked, boiled)||½ cup||141|
|Asparagus (cooked, boiled)||½ cup (~6 spears)||134|
|Spinach (cooked, boiled)||½ cup||131|
|Lima beans (large, mature seeds, cooked, boiled)||½ cup||78|
|Orange juice (raw)||6 fl. oz.||56|
|Spaghetti (enriched, cooked)||1 cup||167*|
|White rice (enriched, cooked)||1 cup||153*|
|Bread (enriched)||1 slice||84*|
The principal form of supplementary folate is folic acid. It is available in single-ingredient and combination products, such as B-complex vitamins and multivitamins.
Daily recommendations for dietary folic acid are:
- Infants, 0 to 6 months: 65 mcg (adequate intake)
- Infants, 7 to 12 months: 80 mcg (adequate intake)
- Children, 1 to 3 years: 150 mcg (RDA)
- Children, 4 to 8 years: 200 mcg (RDA)
- Children, 9 to 13 years: 300 mcg (RDA)
- Teens, 14 to 18 years: 400 mcg (RDA)
- Men and women, 19 years and older: 400 mcg (RDA)
- Pregnant women: 600 mcg (RDA)
- Breastfeeding women: 500 mcg (RDA)
Pregnant women should get 600 mcg of folic acid per day. Women who plan to become pregnant should make sure to get the recommended 400 mcg per day since many neural tube defects can happen shortly after conception and before a woman even knows she is pregnant. Prenatal vitamins contain the needed amount of folic acid for pregnant women.
Can it be harmful?
No adverse effects have been associated with the consumption of excess folate from food. Concerns regarding safety are limited to synthetic folic acid intake.
When megaloblastic anemia, a symptom of B12 deficiency (which is indistinguishable from that associated with folate deficiency) is treated with high doses of folate (5mg), the symptoms may improve but there will be neurological progression of B12 deficiency. In order to prevent this, the recommended intake of folic acid is 1 mg daily. However, there are limited data on the effects of large doses.