Folic acid in diet

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Definition

Folic acid and folate are both terms for a type of B vitamin (vitamin B9).

Folate is a B vitamin that occurs naturally in foods such as green leafy vegetables, citrus fruit, and beans.

Folic acid is man-made (synthetic) folate. It is found in supplements and added to fortified foods.

The terms folic acid and folate are often used interchangeably.

Folic acid is water-soluble. Leftover amounts of the vitamin leave the body through the urine. That means your body does not store folic acid. You need to get a regular supply of the vitamin through the foods you eat or through supplements.

Alternative Names

Folic acid; Polyglutamyl folacin; Pteroylmonoglutamate; Folate

Function

Folate has many functions in the body:

  • Helps tissues grow and cells work
  • Works with vitamin B12 and vitamin C to help the body break down, use, and create new proteins
  • Helps form red blood cells (helps prevent anemia)
  • Helps produce DNA, the building block of the human body, which carries genetic information

Folate deficiency may cause:

It may also lead to certain types of anemias.

Because it's hard to get enough folate through foods, women thinking about becoming pregnant need to take folic acid supplements. Taking the right amount of folic acid before and during pregnancy helps prevent neural tube defects, including spina bifida. Taking higher doses of folic acid before you get pregnant and during the first trimester may lower your chances of miscarriage.  

Folic acid supplements may also be used to treat a lack of folate, and may help with some kinds of menstrual problems and leg ulcers.

Food Sources

Folate occurs naturally in the following foods:

  • Dark green leafy vegetables
  • Dried beans and peas (legumes)
  • Citrus fruits and juices

Fortified means that vitamins have been added to the food. Many foods are now fortified with folic acid. Some of these are:

  • Enriched breads
  • Cereals
  • Flours
  • Cornmeals
  • Pastas
  • Rice
  • Other grain products

There are also many pregnancy-specific products on the market that have been fortified with folic acid. Some of these are at levels that meet or exceed the RDA for folate. Women should be careful about including a high amount of these products in their diets along with their prenatal multivitamin. Taking more is not needed and does not provide any added benefit.

The tolerable upper intake level for folic acid is 1000 micrograms (mcg) a day. This limit is based on folic acid that comes from supplements and fortified foods. It does not refer to the folate found naturally in foods.

Side Effects

Folic acid does not cause harm when used at recommended levels. Folic acid dissolves in water. This means that it is regularly removed from the body through urine, so excess amounts do not build up in the body.

You should not get more than 1000 mcg per day of folic acid. Using higher levels of folic acid can mask vitamin B12 deficiency.

Recommendations

The best way to get the daily requirement of essential vitamins is to eat a wide variety of foods. Most people in the United States get enough folic acid in their diet because there is plenty of it in the food supply.

Folic acid can help reduce the risk of certain birth defects, such as spina bifida and anencephaly.

  • Women who are of childbearing age should take at least 400 micrograms (mcg) of a folic acid supplement every day in addition to that found in fortified foods.
  • Pregnant women should take add 600 micrograms a day, or 1000 micrograms a day if expecting twins.

The Recommended Dietary Allowance (RDA) for vitamins reflects how much of each vitamin most people should get each day.

  • The RDA for vitamins may be used as goals for each person.
  • How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and illnesses, are also important.

The Food and Nutrition Board of the Institute of Medicine Recommended Intakes for Individuals - Daily Reference Intakes (DRIs) for folate:

Infants

  • 0 to 6 months: 65 mcg/day*
  • 7 to 12 months: 80 mcg/day*

*For infants from birth to 12 months, the Food and Nutrition Board established an Acceptable Intake (AI) for folate that is equivalent to the mean intake of folate in healthy, breastfed infants in the United States.

Children

  • 1 to 3 years: 150 mcg/day
  • 4 to 8 years: 200 mcg/day
  • 9 to 13 years: 300 mcg/day

Adolescents and adults

  • Males, age 14 and older: 400 mcg/day
  • Females, age 14 and older: 400 mcg/day
  • Pregnant females of all ages: 600 mcg/day
  • Breastfeeding females of all ages: 500 mcg/day

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Vitamin B9 benefitsVitamin B9 source

References

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. National Academies Press. Washington, DC, 1998. PMID: 23193625 www.ncbi.nlm.nih.gov/pubmed/23193625.

Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.

Mesiano S, Jones EE. Fertilization, pregnancy, and lactation. In: Boron WF, Boulpaep EL, eds. Medical Physiology. 3rd ed. Philadelphia, PA: Elsevier; 2017:chap 56. 

Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 26.

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