Folate is a B vitamin that functions as a coenzyme in the metabolism of nucleic and amino acids. Folate is a generic term that includes both the naturally occurring form of the vitamin (food folate or pteroyl- polyglutamates) and the monoglutamate form (folic acid or pteroylmonoglutamic acid), which is used in fortified foods and dietary supplements. The word ‘folic’ is from the Latin ‘folia’ (leaf), coined in 1941 for an early preparation of this vitamin from spinach leaves.
The requirements for folate are based on the amount of dietary folate equivalents (DFEs, with values adjusted for differences in the absorption of food folate and folic acid) needed to maintain erythrocyte folate. DFEs adjust for the nearly 50 percent lower bioavailability of food folate compared to that of folic acid. The Tolerable Upper Intake Level (UL) is based on the precipitation or exacerbation of neuropathy in vitamin B12–deficient individuals as the critical end-point and represents total intake from fortified food or dietary supplements.
The UL does not include naturally occurring food folate. Although epidemiological evidence suggests that folate may protect against vascular disease, cancer and mental disorders, the evidence was not sufficient to use risk reduction of these conditions as a basis for setting folate requirements.
Rich food sources of folate include fortified grain products, dark green vegetables, and beans and legumes. Chronic inadequate folate intake results in macrocytic anemia. The adverse effect of consuming excess supplemental folate is the onset or progression of neurological complications in people with vitamin B12 deficiency. Excess folate can obscure or mask and thus potentially delay the diagnosis of vitamin B12 deficiency, which can result in an increased risk of progressive, unrecognized neurological damage.
To lower the chances of neural tube defects, pregnant women should take 400 mg of folic acid regularly from fortified foods, supplements, or both, in addition to consuming food folate from a varied diet. It is important to note that this recommendation specifically calls for folic acid, which is more bioavailable than food folate. Since foods fortified to a level of 400 mg are not available in Canada, the recommendation is to consume a multivitamin containing 400 mg of folic acid every day in addition to the amount of folate in a healthful diet.
Food Sources
| Food name | Weight (g) | Folate (µg) | DV% |
| Mung beans | 207 | 1294 | 323.50 |
| Mothbeans | 196 | 1272 | 318 |
| Adzuki beans | 197 | 1225 | 306.25 |
| Chickpeas | 200 | 1114 | 278.5 |
| Yardlong beans | 167 | 1099 | 274.75 |
| Cowpeas | 167 | 1067 | 266.75 |
| Pinto beans | 193 | 1013 | 253.25 |
| Lentils | 192 | 920 | 230 |
| Lima beans | 202 | 808 | 202 |
| White beans | 202 | 784 | 196 |
| Navy beans | 208 | 757 | 189.25 |
| Kidney beans | 184 | 725 | 181.25 |
| Soybeans | 186 | 698 | 174.5 |
| Broadbeans | 150 | 634 | 158.5 |
| Edamame | 155 | 482 | 120.5 |
| Rice | 185 | 475 | 118.75 |
| Mungo beans | 207 | 447 | 111.75 |
| Arrowroot | 120 | 406 | 101.5 |
| Peanuts | 146 | 359 | 89.75 |
| Radishes | 116 | 342 | 85.5 |
Health Benefits of Folate
- Prevent cancer
Folate may protect against cancer of the esophagus and the colon, although evidence at this time is limited. Folate plays roles in DNA synthesis and repair; thus, inadequate folate intakes may allow DNA damage to accumulate. This reason alone is enough to warrant everyone attending to their folate intake.
- 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 (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. 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.
- Crucial 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 (for example, blood cells, and placenta). Most prenatal vitamin supplements include folate to help meet a pregnant woman’s increased needs.
- Prevent heart ailments
Heart ailment is a complex disorder which includes various variables or factors with different role on development. Elevated protein level is known as homocysteine that makes blood vessels inflexible or resistant to change. This could worsen hypertension and promotes the chances of coronary artery disease and strokes. Folate is transformed into metabolite tetrahydrofolate which breaks down homocysteine into useful protein methionine that enhance heart health.
- Cognitive health
Folate is crucial for development of brain even in the womb. Its requirement won’t reduce as we age but rather increased. Individuals having low blood levels of folate has strong correlation to symptoms associated with epilepsy, depression, cognitive decline and psychiatric conditions. The part of brain which promotes memory or learning is also affected resulting in poor function of brain.
Protein homocysteine has toxic or inflammatory effects on neurons in the brain contributing development of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Intake of folate is related with low oxidative damage to brain cells and enhance brain performance especially as people ages or with mild impairment.
- Treat depression
Dopamine and serotonin are two essential transmitters which controls our mood as well as motivation. Levels of these neurotransmitters could be altered due to the combination of individual or external factors. This results in depressive illness or loss of motivation & pleasure with life. This is caused due to low levels of folate as this vitamin is involved in synthesis of both dopamine and serotonin. Increase in folate intake increases production and also stimulates serotonin receptors in brain and promotes the activity of medication that treats depression.
The two most important neurotransmitters that control our mood and motivation are dopamine and serotonin, whose levels may become altered due to a combination of external and individual factors. When this happens, the result is usually some manifestation of depressive illness, or loss of motivation and pleasure with life. One of these causes is low folate levels, since this vitamin is involves in the synthesis of both serotonin and dopamine. Increased folate consumption not only increases production, but also stimulates the serotonin receptors in the brain and can enhance the action of medication used to treat depression.
- Slows down aging
Preserving mental function is crucial for slowing down premature aging. Folate lowers oxidative stress in the body which is the major cause for rapid aging and studies conducted using roundworms showed prolong lifespan.
- Healthy liver
Liver processes various toxins on regular basis and in the process it could be damaged. In alcoholics, effect is worsened as the oxidative damage increases and the antioxidant levels of methionine and glutathione are reduced. Folate helps to maintain these two antioxidants, promotes liver detoxification and combat harmful effect of alcohol on liver.
- Makes bone strong
Folate is considered to be crucial for maintaining bone health. Its deficiency is associated to lower bone density and increases the chances of fractures.
- Strong immunity
T-cell function reduces as we ages and this weakens immunity. Folate deficiency worsens suppression of immunity. Individuals consuming folate found to have increase in resistance to disease. This is due to antioxidant properties of folate that lowers strain on immune system.
Inadequate intake/ deficiency of Folate
Folate deficiency can result in several problems including anemia. Red blood cells (RBCs) have a life span of about 4 months and are constantly reproducing (two million RBCs per 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 is 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, fewer and fewer 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.
Excess intake of Folate
- High folic acid intake could mask the hematological consequences of vitamin B12 deficiency and thus delay its diagnosis. This might increase the spinal and neurological damage caused by B12 deficiency.
- High folate intake could reduce the effectiveness of certain drugs like methotrexate that work by interfering with folate metabolism.
- High folic acid intake might increase the growth of existing bowel cancers or increase the risk of benign bowel adenomas developing into cancers.
- Folic acid used in supplements and for fortifying food might pose risks not posed by natural conjugated forms of folate found in food.
Special Considerations
- Individuals at increased risk: People who are at risk of vitamin B12 deficiency include those who follow a vegan diet, older adults with atrophic gastritis, and those with pernicious anemia and bacterial overgrowth of the gut. These individuals may place themselves at an increased risk of neurological disorders if they consume excess folate because folate may mask vitamin B12 deficiency.
- Females of childbearing age: In general, the prevalence of vitamin B12 deficiency in women of the childbearing years is very low and the consumption of supplemental folate at or above the UL in this subgroup is unlikely to produce adverse effects.
Recommended intakes of Folate
The DRI recommended intake for folate for healthy adults is set at 400 micrograms per day. The DRI committee also advises all women of child-bearing age to consume 400 micrograms of folic acid, a highly available form of folate, from supplements or enriched foods each day in addition to the folate that occurs naturally in their foods.
The recommended daily allowance of folate for people of different ages:
| Age | Amount |
| 0 to 6 months | 65 mcg |
| 7 to 12 months | 80 mcg |
| 1 to 3 years | 150 mcg |
| 4 to 8 years | 200 mcg |
| 9 to 13 years | 300 mcg |
| Over 14 years | 400 mcg |
| During pregnancy | 600 mcg |
| During lactation | 500 mcg |
References:
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