Folic Acid Supplementation Tied to Health Risks for Women and Their Babies

Why Scientists Say Folate from Foods Is the Best Choice

More and more studies are showing alarming health risks for women and their babies as a result of synthetic folic acid supplements and fortification of foods. While folates have long been known to be crucial for healthy fetal development, the synthetic version of folate, folic acid, has been linked to increased risk of asthma for infants and double the risk of breast cancer for mothers, among other risks.

Folate deficiency is linked to spina bifida and other neural tube defects in newborn infants. Because of this risk, pregnant women have long been advised to increase their intake of folates before pregnancy and during early pregnancy to 600 micrograms or more.

Most prenatal vitamins contain a minimum of 800 micrograms of folic acid. In addition, the United States began fortifying grains and cereal products with synthetic folic acid in 1998. Flour, corn meal, white rice, cereals, cereal bars, pasta, and similar items all contain additional synthetic folic acid. This means that many pregnant women are consuming far more folic acid than the recommended dose, which puts them and their developing babies at possible risk.

One Australian study has found that women who take folic acid supplements past early pregnancy have a 30% higher chance of having a child with asthma. Researchers in the study, Effect of Supplemental Folic Acid in Pregnancy on Childhood Asthma: A Prospective Birth Cohort Study, reported:

In our study, supplemental folic acid in late pregnancy was associated with an increased risk of asthma in children, but there was no evidence to suggest any adverse effects if supplements were taken in early pregnancy.

Associate Professor Michael Davies said that folic acid supplements appear to have "additional and unexpected" consequences in recent studies in mice and infants. The researcher explained:

Folate is incredibly important because of its role in preventing neural tube defects (like spina bifida) but because it is so important, and so bioactive, it needs to be treated with some respect as well.

Folate is very important for pregnant women, especially in the first trimester. Folates play a vital role in fetal development, and deficiencies are linked to neural tube defects. Folate deficiencies may have other adverse effects on babies, as well. Studies have linked low folate levels in mothers with increased risk of ADHD in their children and smaller head circumferences, which could indicate a smaller rate of prenatal brain growth.

However, scientists are increasingly wondering if regular folic acid supplementation is necessary, and whether it may actually be harmful. Since many countries have mandatory folic acid fortification of foods (including the United States), some studies are showing that this could lead to an overdose effect and increase in certain cancers. Folic acid supplements have been linked to lower risk of some cancers during early pregnancy but increased cancer risk after birth, for instance.

Another issue with folic acid supplementation is that people with a common mutation of the MTHFR gene are unable to convert synthetic folic acid to folate. Because of this, as many as half of all pregnant women may not be able to adequately absorb synthetic folic acid. Women with this genetic mutation have an increased risk of many conditions such as recurrent miscarriage, increased risk of having a child with autism or Downs Syndrome, an impaired ability to process toxins, fatigue, anxiety, sleep issues, heart disease and many other risks.  Dr. Ben Lynch, an expert on MTHFR polymorphisms explained the problem of folic acid supplementation for women with the MTHFR mutation:

MTHFR takes folic acid and changes it so the body can use it. Folic acid by itself is worthless – it does absolutely nothing – until it is run through various enzymes in the body and transformed into these forms of folate the body can use – such as methyltetrahydrofolate, or commonly shortened as methylfolate.

Women with this genetic mutation can not only not make use of synthetic folic acid, but they also run all of the risks of folate deficiencies for their developing babies no matter how much folic acid they consume. In addition, their health is further compromised by not having the food-derived folate that they need.

The risks of folic acid supplementation do not stop there, however. One study reported in the British Medical Journal found that women who took supplemental folic acid were twice as likely to die of breast cancer. In Taking Folate in Pregnancy and Risk of Maternal Breast Cancer, researchers reported:

In women randomised to high doses of supplemental folate, all cause mortality was about a fifth greater, and the risk of deaths attributable to breast cancer was twice as great.

For the general population, folic acid supplementation can lead to other health problems as well. Dr Siân Astley of Britain's Institute of Food Research says of overfortification:

This can cause problems for people being treated for leukaemia and arthritis, women being treated for ectopic pregnancies, men with a family history of bowel cancer, people with blocked arteries being treated with a stent and elderly people with poor vitamin B status. For women undergoing in-vitro fertilisation, it can also increase the likelihood of conceiving multiple embryos, with all the associated risks for the mother and babies. It could take 20 years for any potential harmful effects of unmetabolised folic acid to become apparent.

In Norway, where there is no fortification of flour with folic acid, researchers conducting a six-year study on the effects of B vitamins in patients with heart disease found that the patients whose supplement included folic acid had a greater risk of cancer incidence and cancer mortality. Not only were the patients who were taking folic acid more likely to develop cancer, but these patients were 43% more likely to die from cancer. Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12, published by the Journal of the American Medical Association, reported:

Experimental findings suggest that excess folic acid may stimulate the growth of established neoplasms (ie, the so-called acceleration phenomenon). There is also the question of potential adverse effects of circulating unmetabolized folic acid. A recent cross-sectional study reported reduced natural killer cell cytotoxicity associated with folic acid in plasma. Thus, folic acid may impair cancer immune defense.

While these risks are associated with folic acid supplements, there is no risk associated with folates obtained from food. It is important to note that synthetic folic acid and folates from food are utilized very differently in the body and have very different effects. One reason for this is that unlike folates, which are metabolized in the stomach, folic acid is metabolized in the liver. The liver is easily saturated and excess folic acid enters the blood stream where it can harm other systems.

Good sources of natural folate include lentils, asparagus, spinach, beans, and liver. It is quite possible to get all the folate you need from a healthy diet.  If you believe you are unable to consume enough natural folate, you may want to supplement your diet with the more bioavailable form of folate, L-methylfolate. You can find this more usable form of folate at health food stores, drug stores and online. L-methylfolate is also sold as “optimized folate.”

It is very important for pregnant women and women who are planning on becoming pregnant to make sure to get enough folate. For the healthiest possible baby and mother, consume it the traditional way—from healthy, whole foods.

Alicia Bayer
Alicia Bayer

Alicia Bayer lives in Minnesota with her husband and 5 children. Her writing has been widely published in books, magazines and online. She is the author of 4 books on foraging, nature studies and homeschooling.

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