Pregnancy isn’t the only time in life to focus on folate. Although this vitamin has gotten the most attention for its importance to a developing fetus, folate plays an essential role throughout our lives. For example, folate is a crucial nutrient for synthesizing DNA, and therefore for cell division.1 Any biological process that involves rapid growth (fetal development, childhood growth, immune function, and cancer) has the potential to be affected by your folate status.
Insufficient folate can have devastating effects on a pregnancy, leading to birth defects. Even before a woman typically discovers she is pregnant, folate already is at work, making it most important to enter into a pregnancy with an adequate folate level.
During the initial four weeks of pregnancy, folate plays an important role in the folding of the neural tube which is the precursor to the brain and central nervous system. In a folate-deficient fetus, the tube may not close completely during folding, causing a neural tube defect. After the folding of the neural tube, folate continues to play an important role in the development of the brain and nervous system. This role is strongly suggested by studies that link low folate status during pregnancy to hyperactivity and other behavior problems in children, and higher folate intake with greater academic achievement in teens.2, 3 Consuming folate-rich foods before and during pregnancy may also offer protection against cardiac birth defects, childhood respiratory illnesses, and childhood cancers.4-8
Folate is also necessary beyond pregnancy and childhood, as this vitamin plays a critical role in supporting our health as adults. Folate is one of the many nutrients necessary for red blood cells to transport oxygen properly, and it also supports the functioning of our nervous and cardiovascular systems. Adequate amounts of B vitamins including folate are important for maintaining good cognitive function throughout life.9-11
Folic Acid is Not Folate
Folate is often called a double-edged sword. Folate deficiency, of course, is harmful. But excess in the form of folic acid has its own dangers. Just to be clear: folic acid is not the same as natural folate. Natural folate is beneficial when provided by whole foods, but may be harmful in supplement form as folic acid. Folate is abundant in green vegetables, beans and other whole plant foods. Synthetic folic acid, which is chemically different than folate, is found in supplements and fortified foods and is twice as absorbable by the human body compared to natural folate.12
While the body converts some synthetic folic acid to folate, it has a limited capacity to do so. Much of the remaining folic acid that is not converted circulates in the blood and tissues unmodified. It is unknown exactly what unmodified folic acid does in the human body. But it has the potential to disrupt normal folate metabolism and there is substantial evidence that it can even promote cancer growth.
In addition, synthetic folic acid can disrupt the actions of natural folate as it has a greater capability to bind to folate receptors on our cells. This, in turn, could result in folic acid being preferentially transported into normal healthy cells instead of natural folate. Once inside the cell, folic acid could then compete with natural folates for other binding sites, preventing them from functioning properly and potentially causing changes in normal gene expression or cell growth rates.
Harmful Effects of Too Much Folic Acid
Since folic acid is more absorbable than natural folate, we run the risk of excess when we ingest the synthetic form. It would be impossible to get excessive folate from natural foods. There is evidence that higher levels of circulating (unmetabolized) folic acid may reduce the protective functions of certain immune cells.13 High folic acid consumption can also mask the symptoms of — and exacerbate — vitamin B12 deficiency, which could be a problem especially for the elderly.14
However, the most significant concern of excess folic acid is cancer development. Since folate is involved in DNA synthesis which is crucial for cell growth and cancer cells have more folate receptors on their surfaces and produce more folate-dependent enzymes than normal cells, excess circulating folic acid could feed into this process and allow cancer cells to proliferate.15 Excess folic acid may also lead to cancer development by producing changes in gene expression.
The idea that folic acid could promote cancer is not new. In the 1940s, high doses of folic acid were given as an experimental treatment to leukemia patients and the rate of proliferation of cancer cells increased. This finding was the origin of the use of anti-folate drugs for cancer chemotherapy today.15
Natural Folate is Ideal
There are studies that suggest that synthetic folic acid from multivitamins is cancer promoting, whereas folate from food is protective.16,17 Other studies have cautioned against supplemental folic acid: A 2011 meta-analysis of six folic acid supplementation trials found that the incidence of cancers was 21 percent higher in the folic acid supplementation groups than control groups.18 Studies on multivitamin use and breast cancer have produced inconsistent findings overall, however several have reported an increase in risk, and have hypothesized that folic acid is the culprit.16,19
Since folic acid can be harmful in supplement form, the formulation for my Women’s and Men’s Daily Formula multivitamins and my Gentle Prenatal do not contain folic acid or other potentially damaging ingredients like beta-carotene, vitamins A and E, or the minerals iron and copper.
Luckily we don’t need to get folic acid from vitamins because folate is plentiful in green vegetables and other whole plant foods. When we get folate from a healthful diet it comes naturally packaged in balance with hundreds of other cancer protective micronutrients.
The recommendation for folate for healthy adults is 400 mcg/day and 600 mcg/day for pregnant women. This quantity can easily be met by eating green vegetables, beans and other whole plant foods.
Learn more about food folate, synthetic folic acid, and their different effects on our health in my Folate Position Paper.
