Essential for a number of your body’s metabolic processes, folic acid is the synthetic version of folate, also known as vitamin B9, folacin, or pteroylglutamic acid. Long known to be vital in the prevention of birth defects, this vitamin is also necessary for cell maintenance and repair, the synthesis of nucleic acids and the formation of heme, the red, iron-carrying component of the haemoglobin in red blood cells.
A deficiency of folic acid can interfere with the formation and maturation of young red blood cells, resulting in folic-acid-deficiency anemia. This anemia is associated with fatigue, weakness, apathy, headaches, irregular heartbeat, sore tongue, diarrhoea, lack of appetite, weight loss, irritability and forgetfulness.
Inadequate levels of folic acid contribute to increased levels of homocysteine. The results of more than 80 studies show that even moderately elevated levels of homocysteine in the blood increase the risk of cardiovascular disease. High homocysteine levels damage arteries, in addition to making blood clot more easily than normal, increasing the risk of heart attack.
Of the three vitamins that regulate homocysteine levels, folic acid has been shown to have the greatest effect in lowering basal levels of homocysteine in the blood when there are also adequate amounts of vitamin B12 and vitamin B6. Increasing folate intake either through consuming folate-rich foods or taking supplements has been found to lower homocysteine levels.
Folate-rich diets have been associated with a lower risk of cardiovascular disease. A study that followed 1,980 Finnish men for ten years found that those who consumed the most dietary folate had a 55 percent lower risk of an acute coronary event when compared with those who consumed the least dietary folate.
Though the results of studies have been mixed, there does seem to be evidence that Folic acid may be helpful in slowing cognitive decline as we age. Low folate levels and high homocysteine have been associated with decreased cognitive performance. Researchers randomly assigned 818 older adults in Holland, aged 50 to 70 years old, to receive 800 mcg of folic acid supplementation daily or a placebo for three years. All participants initially had low folate levels and elevated homocysteine concentrations. According to researchers, those who received the folic acid supplementation had significantly improved cognitive functioning, especially in the areas of memory and information processing speed, as compared to the placebo group.
One cause of cancer is thought to be from too much DNA damage in relation to the rate of DNA repair and/or the wrong expression of critical genes. Because of the important roles that folate plays in DNA and RNA synthesis, it is possible that folate intake affects both DNA repair and gene expression. The consumption of at least five servings of fruits and vegetables a day has been consistently associated with a decreased incidence of cancer. As fruits and vegetables are excellent sources of folate, this may play a role in their anti-carcinogenic effect. Observational studies have found low folate levels to be associated with cancers of the cervix, colon and rectum, lung, esophagus, brain, pancreas, and breast.
But while folate plays a role in the prevention of cancer, there is also growing evidence that it could make some cancers worse. Studies show that people who get plenty of folic acid reduce their risk of developing colorectal cancer and precancerous polyps by 40 to 60 percent. However, folic acid not only helps healthy cells grow, it also helps cancerous cells grow. Studies in animals have shown that once cells are on the path to becoming cancers, the vitamin can make things worse. Therefore, it is important to get an adequate amount of the vitamin, but not too much.
The recommended daily allowances for folic acid intake have increased incrementally over the years as it was found that the former RDA was sufficient only for the prevention of deficiency symptoms severe enough to cause anemia. The RDA for adults is now 400 micrograms per day, and 500 micrograms for pregnant women. Pregnancy increases both the risk and occurrence of folic acid deficiency due to the amount that is used for the rapidly dividing cells of the embryo. Intake levels of up to 1000 micrograms per day have shown benefit in the prevention of cardiovascular disease, Alzheimer’s disease and the prevention of some cancers, though for some groups of people that amount may cause more harm than good, as it may enhance the development of cancerous or pre-cancerous tumours.
The intake of folic acid that results from eating foods that are fortified, such as breakfast cereals, in combination with the additional intake received from the government’s mandatory fortification of flour means that supplementary intake of folic acid is unnecessary for many segments of the population, and may even pose a risk. Women of child-bearing age seem to benefit from supplemental folic acid in regard to its protection against birth defects, though men and those with a family history of certain cancers, such as colorectal, most likely get enough in their usual diet and should not take additional supplements.
If you want to increase your intake of folate, green leafy vegetables, citrus fruits, legumes and fortified cereals are excellent sources. There is also some folic acid synthesised by bacteria in the intestines. As cooking destroys some forms of the vitamin, it is generally recommended that some raw fruits and vegetables be included in the diet. Supplements may also be taken, but be sure you are in need of it as you may already be getting adequate amounts of the vitamin through your diet.