Folate Acids - Action, Sources in Food, Consequences of Deficiency, Supplementation

Folates are a form of folic acid that naturally occurs in food, primarily in plants. They are absorbed in the gastrointestinal tract, specifically in the duodenum and small intestine, where their primary storage site is the liver. In the body, the active form of folic acid, tetrahydrofolate, is a biologically active compound that has a significant impact on cell metabolism. A deficiency in tetrahydrofolate can lead to disruptions in many essential biological processes, such as the synthesis of nucleic acids and proteins, the metabolism of amino acids, hydroxylation of long-chain fatty acids, regulation of homocysteine levels in the blood, formation of the myelin sheath on nerve fibers, function of the hematopoietic and cardiovascular systems, regulation of the formation and maturation of red blood cells, and growth and development processes of all body cells. Furthermore, folates play a significant role in preventing neural tube defects in the fetus and reducing the risk of certain types of cancer, and they are essential for tissues where intensive cell division occurs.

Folic acid is present in a wide range of food products of both plant and animal origin. Valuable sources of folic acid in the diet are: - vegetables (e.g. spinach, celery, asparagus, broccoli, lettuce, cabbage, Brussels sprouts, peas, cauliflower, pepper, parsley, beetroot), - seeds of leguminous plants (e.g. soybeans, beans, lentils, soybeans, peas), - whole grains and products made from wholemeal flour, - fruits (e.g. strawberries, raspberries, oranges, kiwi, mango, avocado), - nuts and seeds of leguminous plants, - yeast, - liver, - milk and dairy products, - eggs, - fatty fish such as salmon. Folic acid is also synthesized by intestinal bacteria, but these amounts are not sufficient for proper functioning of the body. It is recommended to obtain folic acid mainly through the daily diet. It is important to note that unstable forms of folic acid occur in food in conjunction with synthetic products. Folic acid is sensitive to heat, sunlight, oxygen, acidic environments, and metal ions. It is very important to properly store and process foods containing folic acid (i.e., at low temperatures and without access to light). Foods should be consumed as fresh as possible, without cutting (especially with a metal knife), raw or al dente cooked in a small amount of water. The greatest loss of folic acid occurs during thermal processing and can reach up to 50-80%.

The appropriate concentration of folic acid in the blood serum is 6–20 ng/ml, while in erythrocytes it is 160–640 ng/ml. Concentrations below 3 ng/ml in the serum and below 140 ng/ml in red blood cells indicate clinical deficiency. The need for folic acids depends on age and physiological condition. The daily requirement for folic acids in an adult is 400 μg/day, in pregnant women it increases to 600 μg/day, and in lactating mothers it is 500 μg/day. The bioavailability of folic acids is also important, which is influenced by many factors, such as the form of folic acids in the diet, the type of products (natural, synthetic), the method of preparing products containing folic acids (raw, cooked), digestion and absorption, medications, and addictive substances (alcohol, cigarettes). Czeczot H. showed that effective absorption of folic acids in the digestive tract does not exceed 50%. If we ensure a varied and properly balanced diet, it is possible to meet the demand for vitamin B9. To use it even more effectively, it is also important to properly provide the body with other vitamins and mineral components, such as vitamin C, vitamin B12, zinc, and iron. The Polish Society of Gynecologists and Obstetricians recommends additional supplementation in pregnant women due to the increased demand for folic acids.

The body stores approximately 5-10 mg of folic acid, with half of it stored in the liver. Even small deficiencies in this nutrient can lead to serious health consequences, such as neural tube defects, neurological disorders, growth retardation, concentration and memory problems, fatigue, megaloblastic anemia (reduced number and quality of red blood cells due to vitamin B12 or folic acid deficiency), atherosclerosis, neuropsychiatric disorders (depression, dementia, psychosis), development of certain types of cancer (colon, breast, uterus, ovary, lung), and increased homocysteine levels. Causes of folic acid deficiency include: reduced intake from diet, increased body requirement (e.g. during infancy, puberty, pregnancy, and lactation), impaired absorption (e.g. in celiac disease, resection of the intestines), cancer and inflammatory diseases, medications (e.g. antiepileptics, antimalarials, nonsteroidal anti-inflammatory drugs such as ibuprofen), and alcoholism and nicotine dependence.

Gaszyńska J. has shown in her study that the consumption of folie in natural form with nutrition is safe. However, uncontrolled supplementation may be detrimental to health, for example, an excess of folie can mask a deficiency of vitamin B12, which, if diagnosed too late, can lead to permanent damage to the nervous system. In addition, an excess of folie can accelerate the development of cancers such as colon, rectal, and prostate cancer. Furthermore, high doses of folic acid may increase the risk of fetal damage, the development of obesity, insulin resistance, and type 2 diabetes in offspring at a later stage of life. It is important to note that the absorbability of folie from nutrition is about 50%, while the absorbability of synthetic folic acid is 100%. According to the recommendations of the Polish Society of Gynecologists and Obstetricians, women of childbearing age should consume natural products rich in folie and food enriched with this ingredient. In addition, women of childbearing age should take folic acid in a dose of 0.4 mg/day as a prophylaxis of neural tube defects in the fetus. This is particularly important during the period of about 3 months before conception and should be continued throughout pregnancy, postpartum, and breastfeeding. Preparations with documented content and effect should be supplemented. Supplementation should be individually adjusted. Both a deficiency and an excess of folie can have negative health effects.