Folate

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Folate

 

Folate and folic acid are forms of a water-soluble B vitamin. Folate

occurs naturally in food. Folic acid is the synthetic form of this

vitamin that is found in supplements and fortified foods. A key

observation of researcher Lucy Wills nearly 70 years ago led to the

identification of folate as the nutrient needed to prevent the anemia

of pregnancy. Dr. Wills demonstrated that the anemia could be

corrected by a yeast extract. Folate was identified as the corrective

substance in yeast extract in the late 1930s and was extracted from

spinach leaves in 1941.

 

 

Folate is necessary for the production and maintenance of new cells.

This is especially important during periods of rapid cell division

and

growth such as infancy and pregnancy. Folate is needed to make DNA

and

RNA, the building blocks of cells. It also helps prevent changes to

DNA that may lead to cancer. Both adults and children need folate to

make normal red blood cells and prevent anemia.

 

 

What foods provide folate?

Leafy greens such as spinach and turnip greens, dry beans and peas,

fortified cereals and grain products, and some fruits and vegetables

are rich food sources of folate. Some breakfast cereals (ready-to-eat

and others) are fortified with 25% or 100% of the Daily Value (DV)

for

folic acid. The table of selected food sources of folate and folic

acid suggests dietary sources of this vitamin.

Since 1998, food manufacturers in the US have been required to add

folic acid to enriched breads, cereals, flours, corn meals, pastas,

rice, and other grain products. These regulations were specifically

targeted to reduce the risk of neural tube birth defects in newborns.

Since the folic acid fortification program took effect, fortified

foods have become a major source of folic acid in the American diet.

Synthetic folic acid that is added to fortified foods and dietary

supplements has a simpler chemical structure than the natural form of

folate, and is absorbed more easily by the body. After digestion and

absorption however, the two forms are identical and function in

exactly the same manner.

 

 

How much folate do we need?

The Recommended Dietary Allowance (RDA) is the average daily dietary

intake level that is sufficient to meet the nutrient requirements of

nearly all (97-98%) healthy individuals in each life-stage and gender

group. The 1998 RDAs for folate are expressed in a term called the

Dietary Folate Equivalent. The Dietary Folate Equivalent (DFE) was

developed to help account for the differences in absorption of

naturally occurring dietary folate and the more bioavailable

synthetic

folic acid (1 mcg of food folate = 0.6 mcg folic acid from

supplements

and fortified foods).

The 1998 RDAs for folate expressed in micrograms (mcg) of DFE for

adult men and women (aged 19 years and older) is 400 mcg. During

pregnancy the daily intake should be increased to 500 mcg, and the

RDA

for breastfeeding women is 500 mcg.

 

 

The National Health and Nutrition Examination Survey (NHANES III

1988-91) and the Continuing Survey of Food Intakes by Individuals

(1994-96 CSFII) indicated that most adults did not consume adequate

folate. However, the folic acid fortification program has increased

folic acid content of commonly eaten foods such as cereals and

grains,

and as a result diets of most adults now provide recommended amounts

of folate equivalents.

 

 

When can folate deficiency occur?

A deficiency of folate can occur when your need for folate is

increased, when dietary intake of folate is inadequate, and when your

body excretes (or loses) more folate than usual. Medications that

interfere with your body's ability to use folate may also increase

the

need for this vitamin. Some situations that increase the need for

folate include:

pregnancy and lactation (breastfeeding)

alcohol abuse

malabsorption

kidney dialysis

liver disease

certain anemias.

Some medications interfere with the body's ability to utilize folate,

including:

anti-convulsant medications such as dilantin, phenytoin, and

primidone

Metformin, sometimes prescribed to control blood sugar in type 2

diabetes

Sulfasalazine, used to control inflammation associated with Crohn's

disease and ulcerative colitis)

Triamterene, a diuretic

Methotrexate, used in the treatment of some types of cancer, severe

psoriasis, and adult rheumatoid arthritis.

Signs of folate deficiency

Signs of folic acid deficiency are often subtle. Diarrhea, loss of

appetite, and weight loss can occur. Additional signs are weakness,

sore tongue, headaches, heart palpitations, irritability, and

behavioral disorders. Women with folate deficiency who become

pregnant

are more likely to give birth to low birth weight and premature

infants, and infants with neural tube defects. In adults, anemia is a

sign of advanced folate deficiency.

In infants and children, folate deficiency can slow growth rate. Some

of these symptoms can also result from a variety of medical

conditions

other than folate deficiency. It is important to have a physician

evaluate these symptoms so that appropriate medical care can be

given.

 

 

Who may need extra folic acid to prevent a deficiency?

Women of childbearing age, people who abuse alcohol, anyone taking

anti-convulsants or other medications that interfere with the action

of folate, individuals diagnosed with anemia from folate deficiency,

and individuals with malabsorption, liver disease, or who are

receiving kidney dialysis treatment may benefit from a folic acid

supplement.

Folic acid is very important for all women who may become pregnant.

Adequate folate intake during the periconceptual period, the time

just

before and just after a woman becomes pregnant, protects against a

number of congenital malformations including neural tube defects.

Neural tube defects result in malformations of the spine called spina

bifida, and of the skull, and brain anencephaly. The risk of neural

tube defects is significantly reduced when supplemental folic acid is

consumed in addition to a healthful diet prior to and during the

first

month following conception.

 

 

Women who could become pregnant are advised to eat foods fortified

with folic acid or take supplements in addition to eating folate-rich

foods to reduce the risk of some serious birth defects. Taking 400

micrograms of synthetic folic acid daily from fortified foods and/or

supplements has been suggested. The Recommended Dietary Allowance

(RDA) for folate equivalents for pregnant women is 600 micrograms.

 

 

Folate deficiency has been observed in alcoholics. A 1997 review of

the nutritional status of chronic alcoholics found low folate status

in more than 50 percent of those surveyed. Alcohol interferes with

the

absorption of folate and increases excretion of folate by the kidney.

In addition, many alcohol abusers have poor quality diets that do not

provide the recommended intake of folate. Increasing folate intake

through diet, or folic acid intake through fortified foods or

supplements, may be beneficial to the health of alcoholics.

 

 

Anti-convulsant medications such as dilantin increase the need for

folate. Anyone taking anti-convulsants and other medications that

interfere with the body's ability to use folate should consult with a

medical doctor about the need to take a folic acid supplement.

 

 

Anemia is a condition that occurs when red blood cells cannot carry

enough oxygen. It can result from a wide variety of medical problems,

including folate deficiency. Folate deficiency can result in the

formation of large red blood cells that do not contain adequate

hemoglobin, the substance in red blood cells that carries oxygen to

your body's cells. Your physician can determine whether an anemia is

associated with folate deficiency and whether supplemental folic acid

is indicated.

 

 

Several medical conditions increase the risk of folic acid

deficiency.

Liver disease and kidney dialysis increase excretion (loss) of folic

acid. Malabsorption can prevent your body from using folate in food.

Medical doctors treating individuals with these disorders will

evaluate the need for a folic acid supplement.

 

 

What is the health risk of too much folic acid?

The risk of toxicity from folic acid is low. The Institute of

Medicine

has established a tolerable upper intake level (UL) for folate of

1,000 mcg for adult men and women, and a UL of 800 mcg for pregnant

and lactating (breast-feeding) women less than 18 years of age.

Supplemental folic acid should not exceed the UL to prevent folic

acid

from masking symptoms of vitamin B12 deficiency.

 

 

Caution about folic acid supplements

Beware of the interaction between vitamin B12 and folic acid.

Folic acid supplements can correct the anemia associated with vitamin

B12 deficiency, but folic acid will not correct changes in the

nervous

system that result from vitamin B12 deficiency. Permanent nerve

damage

can occur if vitamin B12 deficiency is not treated. Intake of

supplemental folic acid should not exceed 1,000 micrograms (mcg) per

day to prevent folic acid from masking symptoms of vitamin B12

deficiency.

It is very important for older adults to be aware of the relationship

between folic acid and vitamin B12 because they are at greater risk

of

having a vitamin B12 deficiency. If you are 50 years of age or older,

ask your physician to check your B12 status before you take a

supplement that contains folic acid.

 

 

Current Issues and Controversies about Folate

Folic acid and heart disease

A deficiency of folate, vitamin B12, or vitamin B6 may increase your

level of homocysteine, an amino acid normally found in your blood.

There is evidence that an elevated homocysteine level is an

independent risk factor for heart disease and stroke. The evidence

suggests that high levels of homocysteine may damage coronary

arteries

or make it easier for blood clotting cells called platelets to clump

together and form a clot. However, there is currently no evidence

available to suggest that lowering homocysteine with vitamins will

reduce your risk of heart disease. Clinical intervention trials are

needed to determine whether supplementation with folic acid, vitamin

B12 or vitamin B6 can lower your risk of developing coronary heart

disease.

Folic acid and cancer

Some evidence associates low blood levels of folate with a greater

risk of cancer. Folate is involved in the synthesis, repair, and

functioning of DNA, our genetic map, and a deficiency of folate may

result in damage to DNA that may lead to cancer. Several studies have

associated diets low in folate with increased risk of breast,

pancreatic, and colon cancer. Findings from a study of over 121,000

nurses suggested that long-term folic acid supplementation (for 15

years) was associated with a decreased risk of colon cancer in women

aged 55 to 69 years of age. However, associations between diet and

disease do not indicate a direct cause. Researchers are continuing to

investigate whether enhanced folate intake from foods or folic acid

supplements may reduce the risk of cancer. Until results from such

clinical trials are available, folic acid supplements should not be

recommended to reduce the risk of cancer.

Folic acid and methotrexate for cancer

Folate is important for cells and tissues that rapidly divide. Cancer

cells divide rapidly, and drugs that interfere with folate metabolism

are used to treat cancer. Methotrexate is a drug often used to treat

cancer because it limits the activity of enzymes that need folate.

Unfortunately, methotrexate can be toxic, producing side effects such

as inflammation in the digestive tract that make it difficult to eat

normally. Leucovorin is a form of folate that can help " rescue " or

reverse the toxic effects of methotrexate. It is not known whether

folic acid supplements can help control the side effects of

methotrexate without decreasing its effectiveness in chemotherapy. It

is important for anyone receiving methotrexate to follow a medical

doctor's advice on the use of folic acid supplements.

Folic acid and methotrexate for non-cancerous diseases

Low dose methotrexate is used to treat a wide variety of non-

cancerous

diseases such as rheumatoid arthritis, lupus, psoriasis, asthma,

sarcoidoisis, primary biliary cirrhosis, and inflammatory bowel

disease. Low doses of methotrexate can deplete folate stores and

cause

side effects that are similar to folate deficiency. Both high folate

diets and supplemental folic acid may help reduce the toxic side

effects of low dose methotrexate without decreasing its

effectiveness.

Anyone taking low dose methotrexate for the health problems listed

above should consult with a physician about the need for a folic acid

supplement.

 

 

Food sources of folate and folic acid

Green leafy vegetables, dry beans and peas, and many other types of

vegetables and fruits are good sources of folate. In addition,

fortified foods are a major source of folic acid. It is not unusual

to

find foods such as cereals fortified with 100 percent of the RDA for

folate. The variety of fortified foods available has made it easier

for women of childbearing age to consume the recommended 400 mcg of

folic acid per day from fortified foods and/or supplements. The large

numbers of fortified foods on the market, however, also raise concern

that intake may exceed the UL. This is especially important for

anyone

at risk of vitamin B12 deficiency, which can be masked by too much

folic acid. It is important for anyone who is considering taking a

folic acid supplement to first consider whether their needs are being

met by adequate sources of dietary folate and folic acid from

fortified foods.

Ready to eat cereal, fortified with 100% of the DV, 3/4 c: 400 mcg ~

100% of Daily Value (DV)

Beef liver, cooked, braised, 3 oz: 185 mcg ~ 45% DV

Cowpeas (blackeyes), immature, cooked, boiled, 1/2 c: 105 mcg ~ 25%

DV

Spinach, frozen, cooked, boiled, 1/2 c: 100 mcg ~ 25% DV

Great Northern beans, boiled, 1/2 c: 90 mcg ~ 20% DV

Asparagus, boiled, 4 spears: 85 mcg ~ 20% DV

Wheat germ, toasted, 1/4 c: 8o mcg ~ 20% DV

Orange juice, 3/4 c: 70 mcg ~ 20% DV

Vegetarian baked beans, canned, 1 c: 60 mcg ~ 15% DV

Spinach, raw, 1 c: 60 mcg ~ 15% DV

Rice, white, long-grain, parboiled, cooked, enriched, 1/2 c: 45 mcg ~

10% DV

Avocado, 1/2 c sliced: 45 mcg ~ 10% DV

 

 

Information provided by

National Institutes of Health

 

 

Article Created: 2001-03-07

Article Updated: 2001-03-07