What is folate?
The name folate, as well as the other names associated with this vitamin (folacin and folic acid), suggests its food sources. Folium is Latin for foliage or forage.
What foods in the diet contribute folate?
As its name suggests better food sources of folate include green leafy vegetables such as spinach, turnip greens, and asparagus (see Folate in Food Table). Other vegetables and many fruits, juices, and organ meats also are good contributors of folate. Folate’s molecular structure is somewhat unstable when it is heated, making fresh, uncooked fruits and vegetables better sources than cooked foods. The RDA for adults is 400 µg of folate daily and the DRI/RDA Table presents minimum folate recommendations for all age groups.
What is Folate + Good Food Folate Sources + What does Folate do in our Body + Deficiency and Toxicity of Folate
What does folate do in the body?
Earlier we mentioned that when most molecules are made in the body they are constructed from smaller molecules or parts of other molecules. Folate, functioning as a coenzyme, is dedicated to transferring small, single carbon atom-containing molecules to the processes involved in making some pretty special molecules (see Folate Recycling Figure). Key roles for Folate include:
DNA Production – Before cells can reproduce they must make a copy of their DNA The necessity of folate is particularly realized in cells that rapidly reproduce. This includes cells associated with the body surfaces (i.e., skin, hair, and digestive, urinary, and reproductive tracts) as well as blood cells and certain liver cells. Cells of these tissues must constantly be replaced or turned over to guarantee proper function and integrity. However, in order for these cells to reproduce they must first make a duplicate copy of their DNA so that when the cell divides into two cells, both will get a complete set of DNA.
Amino Acid Metabolism – Folate is also involved in transferring single-carbon molecules in the metabolism of certain amino acids as well. For instance, folate helps convert homocysteine to methionine.
Homocysteine Metabolism – Recently a link has been made between homocysteine levels and heart disease. When folate transfers a carbon molecule to homocysteine it is converted to methionine (see Folate Recycling Figure).The conversion requires the help of vitamin B12 as well. Therefore, a deficiency of folate and/or vitamin B12 can allow for homocysteine levels to become elevated. Vitamin B6 is also important because it helps folate pick up the carbon unit that will be added to homocysteine to form methionine.
How important is folate during pregnancy?
Because folate is fundamentally involved in DNA production and thus the reproduction of cells, periods of life when rapid growth occurs demand a higher folate intake. During pregnancy a woman’s diet must include extra folate to assist in the rapid reproduction of cells of the unborn infant and herself (e.g., blood cells, placenta). Family/Your Health provides more details to what can happen if folate status is inadequate during pregnancy. Most prenatal vitamin supplements include folate to help meet a pregnant woman’s increased needs.
What happens if too little folate is consumed?
Folate deficiency can result in several problems including anemia. Red blood cells (RBCs) have a life span of about four months and are constantly reproducing (about 2 million RBC/second) in bone marrow to compensate for their normal destruction. Although RBCs do not contain a nucleus (with its DNA), there is a time in its development when each new RBC created from the division of another cell. Before that cell divided into two new cells, it needed to copy its DNA. During folate deficiency, the original cell cannot properly copy its DNA because folate is not present to help construct the building blocks of DNA. This results in the development of large and immature RBCs, which then enter the blood and are readily noticeable with a microscope. Furthermore, less and less normal RBCs are produced, resulting in anemia. Anemia is a significant reduction in the level of hemoglobin in the blood. Remember: hemoglobin is found in RBCs, so a reduction in RBC concentration in our blood results in less hemoglobin. The anemia that results from folate deficiency is clinically referred to as macrocytic megaloblastic anemia. Macrocytic means big cell and megaloblast is the name for the pre-RBC form, which still has its nucleus. These changes in RBCs can be observed as early as a few months after consuming a folate-deficient diet.
Can folate be toxic?
Folate toxicity is rare for two principal reasons. First, it is difficult to consume too much folate through normal consumption of foods. Second, the folate content of nutrition supplements is limited by the government. The limitation in supplements is due to to an overlap between folate metabolism and vitamin B12 function. Vitamin B12 is fundamentally involved in folate metabolism in cells as it keeps folate in a form that can be used over and over again in cells (See Folate Recycling Figure). This means that a deficiency in vitamin B12 can in turn decrease folate recycling, resulting in the development of the anemia mentioned previously. Therefore, signs of a folate deficiency can actually help physicians identify a vitamin B12 deficiency. By taking higher dosages of folate (supplements) we can overcome the need for vitamin B12 in the recycling of existing folate in the cells. This is good for folate, but the vitamin B12 deficiency still remains and may go undetected. Thus, folate supplementation has eliminated an early warning sign (anemia) of vitamin B12 deficiency. If the vitamin B12 deficiency progresses it can lead to paralysis and death.