Saskatchewan Institute on Prevention of Handicaps

Folic Acid and the Prevention of Neural Tube Defects

After many years of uncertainty and controversy, scientific evidence now available proves that increasing folic acid intake in the preconception and prenatal period can substantially reduce the occurrence of neural tube defects such as spina bifida.

What are Neural Tube Defects (NTDs)?

Neural tube defects are congenital malformations which include such conditions as spina bifida, anencephaly and encephalocoele.

The neural tube is the embryonic structure that develops into the brain and spinal cord. Every unborn infant's spine is open when it first forms, but it normally closes by the 29th day following conception. In the case of a neural tube defect, the backbone and spinal cord never close completely.

Spina bifida is the most common form of neural tube defect and involves a malformation of the vertebrae and possible damage to the nervous system. The spinal cord and its coverings protrude through splits or openings between the vertebrae, resulting in a bulge or "sac," which can occur anywhere along the back from the neck to the buttocks. The majority, however, appear on the lower back.

How is a child affected?

A child born with spina bifida may have permanent paralysis of the lower limbs and may lack bowel and bladder control. An excessive accumulation of spinal fluid in the brain may occur, leading to enlargement of the head and impairment of brain function.

How many children are born with NTDs?

In Saskatchewan, approximately one baby is born with an NTD for every thousand babies born. Each year in Saskatchewan, 10 to 20 babies are born with this condition.

What causes NTDs?

The cause of NTDs is largely unknown. Experts believe that the cause is related to both genetic and environmental factors.

A woman who has given birth to an affected infant is at a higher risk of having another affected child. When one or more other members of the immediate family have had an NTD affected child there is a higher risk for other family members. Intermediate risk factors include: poor nutrition possibly associated with poverty or economic disadvantage, sprue and coeliac disease, diabetes, alcoholism, women taking anticonvulsant drugs.

Can Neural Tube Defects be prevented?

Several studies conducted in Britain, Hungary and the United States confirm that folic acid decreases the occurrence of NTDs. Women who consume recommended doses of folic acid can reduce the risk of having a child with an NTD by as much as 50 percent.

Women in the high risk group can reduce their risk by as much as 70 percent. A woman should begin taking folic acid at least one month before conception and continue for two months following the last menstrual period.

What is Folic Acid?

Folic acid is one of the "B" vitamins and is found in citrus fruits, raw leafy green vegetables, beans, peas, lentils, cereal, bread and liver.

How much Folic Acid should be taken to reduce the risk of NTDs?

  1. It is recommended that all women take 0.4 mg of Folic Acid for at least a month prior to conception.
  2. Women with an intermediate risk, who are contemplating pregnancy, should take between 1.0 and 4.0 mg of folic acid daily under the supervision of a physician.
  3. All women in the highest risk category, who are contemplating pregnancy, should receive 4.0 mg supplementary folic acid daily, ideally under the supervision of a physician.

How can a woman make sure she gets enough Folic Acid?

There are several ways to obtain the recommended daily dose of folic acid. Some health professionals recommend that women achieve their daily dose by eating an abundance of foods containing folic acid. Although folic acid is found in many foods, it may be difficult to get the entire amount from food due to the small amounts contained in those foods. Other health professionals recommend that, in addition to eating foods high in folic acid, women take a multivitamin supplement containing 0.4 mg of folic acid every day. However, taking more than 1 mg of folic acid is not recommended unless prescribed by a physician.

One of the best ways to ensure that all women of childbearing age achieve the minimum daily dose of folic acid is to fortify foods like flour and other cereal products with folic acid. This could be done in the same way that vitamin D is added to milk. This method has been adapted throughout the United States and has begun to be implemented in Canada.

Regardless of how a woman chooses to take folic acid, optimal perinatal intake of folic acid is the most important single requirement for preventing NTDs in North America today. Women concerned with neural tube defects or folic acid should consult a physician.

Information for this article was adapted from

Laxdal, Oliver E., Habbick, Brian, Bolaria, Rosemary. "Folic Acid Prevents Neural Tube Defects." In Saskatchewan Medical Journal, Vol.4, No.1.
Continuing Medical Education, College of Medicine, University of Saskatchewan: March 1993.
March of Dimes. Spina Bifida Public Health Education Information Sheet. White Plains, New York: 1992. SOGC's Genetics Committee and Council. Society of Obstetrician
& Gynecologist of Canada Policy Statement, The Use of Folic Acid For the Prevention of Neural Tube Defects. Ottawa: March 1993.
Spina Bifida Association of Canada. Winnipeg, Manitoba: 1992. (Pamphlet)
Spina Bifida Association of Canada. Good Dietary Sources of Folic Acid. Winnipeg, Manitoba: 1992. Folic Acid Project Alliance.
Folic Acid: How can this vitamin help you have a healthy baby? Winnipeg, Manitoba: 1994. (Pamphlet)