FOLIC ACID

Folate is the natural form of vitamin B9, which includes naturally occurring food folate and folic acid in supplements and fortified foods. The term folic acid relates specifically to the fully oxidized monoglutamate form of the vitamin synthesized for commercial use in supplements and fortified foods.

Folic acid is required for the multiplication of red blood cells. It is one of the 2 vitamins associated with megaloblastic anemia (along with Vitamin B12).

Why is Folic acid essential for the body?

• Folate, also known as vitamin B9, is essential for good health. Folate helps to form DNA and RNA and is involved in protein metabolism.
• Folate is also important for pregnant women. Low blood levels of folate during pregnancy can cause neural tube defects-anencephaly (a defect in the closure of the neural tube) and spina bifida (a congenital defect in which the spinal column is imperfectly closed). 
• High levels of homocysteine are associated with an increased risk of cardiovascular disease. Folate and vitamin B12 are involved in homocysteine metabolism. Research suggests that these micronutrients reduce the risk of cardiovascular disease by lowering homocysteine levels.

• Folate plays a dual role in cancer prognosis. When given in the early stages of cancer, folic acid helps suppress cancer development in healthy tissues. But high doses of folate after tumor development might promote cancer progression.

What are the signs and symptoms of folic acid deficiency?

If there is inadequate dietary folate, the deficiency will show an effect on the cells that rapidly divide, for example, red blood cells. This can cause megaloblastic anemia. This is characterized by large, abnormally nucleated RBCs that accumulate in the bone marrow.

Pregnant women are at a higher risk of developing folate deficiency because of increased demand for folate. In addition to megaloblastic anemia, inadequate folate intake is associated with poor pregnancy outcomes. 

Folic acid deficiency during pregnancy is associated with:

• increased risk of preterm delivery
• infant low birth weight
• fetal growth retardation

An elevated maternal homocysteine concentration leads to increased habitual spontaneous abortion and pregnancy complications which may increase the risk of low birth weight and preterm delivery.

As folate levels in the pregnant woman go from adequate to poor, there is a 10-fold risk of fetal neural tube defects (NTDs). Between days 21 and 27 post-conception, the neural plate closes to form what will eventually be the spinal cord. Spina bifida, cleft lip, and palate are some of the most common birth defects due to folic acid deficiency during pregnancy.

What is the daily requirement of folic acid?

The recommended dietary intakes for folic acid by the Indian Council of Medical Research (ICMR) is as follows:

What are the food sources of folic acid?

Folate occurs naturally in foods. Although folate is present in a wide range of foods, it is present in a relatively low density.

Diets that contain adequate amounts of fresh green vegetables (i.e. three servings per day) will be good folate sources. Folate losses during harvesting, storage, distribution, and cooking can be considerable. Similarly, folate derived from animal products can be lost during cooking. Some staples, such as white rice, are low in folate.

Rich sources: Liver, dried yeast, green leafy vegetables, wheat germ, and rice polishings.

Good sources: Whole cereals, dried legumes (pulses have twice as much folic acid as cereals), nuts, fresh oranges.

Fair sources: Milled cereals, other vegetables, milk, and fruits.

It is important to remember that the natural folates found in foods are in a conjugated form, which reduces their bioavailability by as much as 50%. In addition, natural folates are much less stable.

Can a high intake of folic acid lead to toxic effects?

There is no evidence to suggest that it is possible to consume sufficient natural folate to pose a risk of toxicity. However, this does not apply to folic acid given in supplements or fortified foods. The main concern with the fortification of high levels of folic acid is the masking of the diagnosis of pernicious anemia. High levels of folic acid correct the anemia, allowing the neuropathy to progress undiagnosed to a point where it may become irreversible, even upon treatment with vitamin B12.

The United States National Academy of Sciences (NAS), has suggested an upper level of 1000 µg/day. There is probably no great risk of toxicity at a range of intakes between 400 and 1000 µg/day of folic acid.

For favorable results, folate must be taken in the first few weeks after conception or before a woman knows she is pregnant. At least 400 mcg of folate is required daily. This isn’t always easy to get from food that is not fortified. That is why women of childbearing age are urged to take extra folic acid as a supplement.

More recently, the biomarker plasma homocysteine has been identified as a very sensitive indicator of folate status and is added to the list of possible indicators of folate adequacy. Any elevation in plasma homocysteine, maybe undesirable because it is a risk factor for chronic disease.

Vitamin B12 is necessary for the conversion of folic acid in the body. Vitamin B12 deficiency causes a rise in unconjugated folates and a marked depletion of intracellular conjugated folates. Folate and vitamin B12 work together to produce S-adenosylmethionine (SAMe), a compound involved in immune function and mood.