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How Folate Can Help Prevent Birth Defects FDA Consumer July 1996, Revised February 1999 How Folate Can Help Prevent Birth Defectsby Paula Kurtzweil If you plan to have children some day, here's important information for the future mother-to-be: Think folate now. Folate is a B vitamin found in a variety of foods and added to many vitamin and mineral supplements as folic acid, a synthetic form of folate. Folate is needed both before and in the first weeks of pregnancy and can help reduce the risk of certain serious and common birth defects called neural tube defects, which affect the brain and spinal cord. The tricky part is that neural tube defects can occur in an embryo before a woman realizes she's pregnant. That's why it's important for all women of childbearing age (15 to 45) to include folate in their diets: If they get pregnant, it reduces the chance of the baby having a birth defect of the brain or spinal cord. "Adequate folate should be eaten daily and throughout the childbearing years," said Elizabeth Yetley, Ph.D., a registered dietitian and director of FDA's Office of Special Nutritionals. Folate's potential to reduce the risk of neural tube defects is so important that the Food and Drug Administration requires food manufacturers to fortify enriched grain products with folic acid. This will give women one way to get sufficient folate: by eating fortified breads and other grain products, such as enriched pasta, rice, waffles and cereal bars. Other ways to do this are: - Eat fruits, dark-green leafy vegetables, dried beans and peas, and other foods that are natural sources of folate. - Eat folic acid-fortified enriched cereal grain products and breakfast cereals. - Take a vitamin supplement containing folic acid. Nutrition information on food and dietary supplement labels can help women determine whether they are getting enough folate, which is 400 micrograms (0.4 milligrams) a day before pregnancy and 800 micrograms a day during pregnancy. Neural Tube Birth Defects The technical names of the two major neural tube birth defects reduced by adequate folate intake are anencephaly and spina bifida. Babies with anencephaly do not develop a brain and are stillborn or die shortly after birth. Those with spina bifida have a defect of the spinal column that can result in varying degrees of handicap, from mild and hardly noticeable cases of scoliosis (a sideways bending of the spine) to paralysis and bladder or bowel incontinence. With proper medical treatment, most babies born with spina bifida can survive to adulthood. But they may require leg braces, crutches, and other devices to help them walk, and they may have learning disabilities. About 30 percent have slight to severe mental retardation. The national Centers for Disease Control and Prevention estimate that about 2,500 infants with spina bifida and anencephaly are born each year in the United States. Other maternal factors also may contribute to the development of neural tube defects. These include: - family history of neural tube defects - prior neural tube defect-affected pregnancy - use of certain antiseizure medications - severe overweight - hot tub use in early pregnancy - fever during early pregnancy - diabetes. Folate Link Scientists first suggested a link between neural tube birth defects and diet in the 1950s. The incidence of these conditions has always been higher in low socioeconomic groups in which women may have poorer diets. Also, babies conceived in the winter and early spring are more likely to be born with spina bifida, perhaps because the mother's diet lacks fresh fruits and vegetables--which are good sources of folate--during the early weeks of pregnancy. In 1991, British researchers found that 72 percent of women who had one pregnancy with a neural tube birth defect had a lower risk of having another child with this birth defect when they took prescription doses of folic acid before and during early pregnancy. Another study looked at folic acid intake in Hungarian women. The evidence indicated that mothers who had never given birth to babies with neural tube defects and who took a multivitamin and mineral supplement with folic acid had less risk in subsequent pregnancies for having babies with neural tube defects than women given a placebo. These studies led the U.S. Public Health Service in September 1992 to recommend that all women of childbearing age capable of becoming pregnant consume 0.4 mg of folate daily to reduce their risk of having a pregnancy affected with spina bifida or other neural tube defects. That corresponds to FDA's Daily Value for folic acid, which is 400 micrograms for nonpregnant women, as well as children 4 and older and adult men. For pregnant women, the Daily Value jumps to 800 micrograms. Daily Values are dietary reference numbers used on the Nutrition Facts panel on food labels to show the amounts of various nutrients in a serving of food. Many women between 19 and 50 consume much less than 400 micrograms of folate a day, according to the U.S. Department of Agriculture. Folate Sources Folate occurs naturally in a variety of foods, including liver; dark-green leafy vegetables such as collards, turnip greens, and Romaine lettuce; broccoli and asparagus; citrus fruits and juices; whole-grain products; wheat germ; and dried beans and peas, such as pinto, navy and lima beans, and chickpeas and black-eyed peas. Under FDA's folic acid fortification program, which became effective January 1998, the agency requires manufacturers to add from 0.43 mg to 1.4 mg of folic acid per pound of product to enriched flour, bread, rolls and buns, farina, corn grits, cornmeal, rice, and noodle products. A serving of each product will provide about 10 percent of the Daily Value for folic acid. Whole-grain products do not have to be enriched because they contain natural folate. Some of the natural folate in non-whole-grain products is lost in the process of refining whole grains. Folate also can be obtained from dietary supplements, such as folic acid tablets and multivitamins with folic acid, and from fortified breakfast cereals. A report recently released by the Institute of Medicine indicates that the evidence suggests that folic acid, the synthetic form of folate, may be better absorbed than folate found naturally in foods. The report also points out that, if taken in adequate amounts, food folate may eventually be demonstrated to be as effective as folic acid. Some Good Sources of Folate * based on Daily Value for folate of 400 micrograms (Source: Food Values of Portions Commonly Used, 16th edition) Finding Foods with Folate Certain information on food and dietary supplement labels can help women spot foods containing substantial amounts of folate. Some labels may claim that the product is "high in folate or folic acid," which means a serving of the food provides 20 percent or more of the Daily Value for folic acid. Or the label may say the food is a "good source" of folate, which means a serving of the food provides 10 to 19 percent of the Daily Value for folic acid. The exact amount will be given in the label's Nutrition Facts panel. Some food and dietary supplement labels may carry a longer claim that says adequate folate intake may reduce the risk of neural tube birth defects. Products carrying this claim must: - provide 10 percent or more of the Daily Value for folic acid per serving - not contain more than 100 percent of the Daily Value for vitamins A and D per serving because high intakes of these vitamins are associated with other birth defects - carry a caution on the label about excess folic acid intake, if a serving of food provides more than 100 percent of the Daily Value for folic acid. FDA has set 1 mg (or 1,000 micrograms) of folate daily as the maximum safe level. There are limited data on the safety of consuming more than 1 mg daily, and there may be a risk for people with low amounts of vitamin B12 in their bodies--for example, older people with malabsorption problems, and people on certain anticancer drugs or drugs for epilepsy whose effectiveness can diminish when taken with high intakes of folate. - list on the label's Nutrition or Supplement Facts panel the amount by weight in micrograms and the %Daily Value of folate per serving of the product. This information, which appears toward the bottom of the panel, along with the listing of other vitamins and minerals, can be used to compare folate levels in various foods and supplements. Other Considerations The claim about folate cannot imply that adequate folate intake alone will ensure a healthy baby, since so many factors can affect a pregnancy. Women should bear this in mind when contemplating pregnancy, advises Jeanne Latham, a registered dietitian and consumer safety officer in FDA's Office of Special Nutritionals. "Folate can make a significant contribution," she said, "many factors, including an overall good diet, are involved in having a healthy baby." Genetics plays a role, as do other healthful prenatal practices, such as eating an all-around good diet. But unlike genetics, diet is a risk factor women can modify to their--and their baby's--advantage, said Jeanne Rader, Ph.D., director of the division of science and applied technology in FDA's Office of Food Labeling. "Folic acid is one of many nutrients needed in a healthy diet for women of childbearing age," she said. "A well-balanced diet with a variety of foods can provide all those nutrients, including adequate amounts of folate." Women have options for reaching the folate intake goal: They can get the necessary nutrients and calories both before and during pregnancy by eating a well-balanced diet, keeping in mind folate-rich foods, nutrition experts say. Folic acid-fortified grain products, including breakfast cereals, will help, too. Dietary supplements are another source of folate. Any one or a combination of these options for ensuring adequate folate can help assure women of childbearing age that, if they become pregnant, their babies will be off to a healthy start. Paula Kurtzweil is a member of FDA's public affairs staff. More InformationFor more information on having a healthy baby, contact: Maternal and Child Health Clearinghouse 5600 Fishers Lane, Room 18A-55 Rockville, MD 20857 March of Dimes Birth Defects Foundation 1275 Mamaroneck Ave. White Plains, NY 10605 Voice mail only: (914) 997-4750 World Wide Web: http://www.modimes.org/
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Dokazano je da neadekvatan unos folne kiseline prije začeća i tijekom prvih 12 tjedana trudnoće dovodi do defekta neuralne cijevi u fetusa. Stoga se preporučuje da sve žene u reproduktivnoj dobi te one koje planiraju trudnoću ili trudnice u ranom razdoblju trudnoće, barem od 4. tjedna, svakodnevno uzimaju folnu kiselinu u dozi od 400ug. No, kako postići taj unos i gdje nalazimo folnu kiselinu u hrani? Sprječava porođajne malformacije Još davne 1931. godine Lucy Willis je opisala kako je ekstrakt kvasca učinkovit protiv makrocitne anemije kasne trudnoće u Indiji. To je bio prvi zapis o korištenju folne kiseline u svrhu prevencije bolesti. Ipak, folna kiselina nije izolirana i njezina struktura nije rasvijetljena još dugi niz godina. Štoviše, prošlo je više od pola stoljeća dok nije prepoznata važnost folne kiseline u preventivnoj medicini, a spoznaje su kulminirale objavom serije znanstvenih radova 1991. godine kada je potvrđeno da perikoncepcijski unos folne kiseline sprječava spina bifidu. Radi se o jednom od najvažnijih otkrića medicine 20. stoljeća, odnosno spoznaji da se suplementacijom folne kiseline smanjuje postotak oštećenja živčanog sustava novorođenčeta za 50 do 80 posto. Naime, niska razina folata u serumu buduće majke može biti značajan čimbenik rizika za pojavu oštećenja živčane cijevi novorođenčeta. To za novo biće konkretno znači da se značajno smanjuje vjerojatnost invaliditeta ili problema u kontroli crijeva i mjehura. Danas postoje inicijative saniranja deficita i na razini populacije te se hrana, najčešće žitarice, obogaćuje folnom kiselinom, primjerice u SAD-u i Velikoj Britaniji. Sve su te mjere pridonijele značajnom sniženju stope porođajnih malformacija, posebice spina bifidae. Istraživanja pokazuju da velik broj ljudi pati od blagog deficita folne kiseline što se očituje razdražljivošću, mentalnim umorom i nesanicom. Suplementacija prije začeća Folna kiselina ima esencijalnu ulogu u sintezi i diobi DNA (genetički kod za replikaciju svake nove stanice) i dijelova RNA koji su potrebni za sintezu proteina u svim stanicama. Stoga "brzorastuća" tkiva, kao fetus ili stanice koje se moraju brzo obnavljati poput crvenih krvnih stanica i stanica imunološkog sustava, imaju veliku potrebu za folnom kiselinom. Folna kiselina je nutrijent koji osigurava normalan rast i razvoj, a posebno je važna za funkciju živčanog i probavnog sustava, spolnih organa te stvaranje bijelih krvnih stanica. Regulira razvoj živčanih stanica embrija i fetusa te sprječava oštećenje živčane cijevi. Liječi anemiju uzrokovanu alkoholizmom, anemiju trudnica, dojilja, žena koje uzimaju oralne kontraceptive i osoba koje boluju od bolesti jetre te hemolitičku anemiju. Pomaže metabolizam aminokiselina i sintezu proteina. Niska razina folata u serumu buduće majke može biti značajan čimbenik rizika za pojavu oštećenja živčane cijevi novorođenčeta. Važno je naglasiti da se većina oštećenja uzrokovanih deficitom folne kiseline pojavljuje tijekom prvih nekoliko tjedana trudnoće. Stoga je suplementacija prije začeća neophodna, posebice za žene koje su koristile oralne kontraceptive, zbog toga što popratna pojava korištenja može biti i smanjenje razine folne kiseline u serumu. Zbog bitne uloge u dijeljenju stanica i formiranju određenih struktura fetusa, sve žene reproduktivne dobi trebaju pripaziti na adekvatan unos folne kiseline. Većina žena ne unosi dovoljne količine folata putem hrane tijekom onoga ključnog razdoblja - prije nego što shvate da su trudne. A to je vrijeme kada je adekvatan unos folata od najveće važnosti. Istraživanja ukazuju da pravilan unos folne kiseline prije i tijekom rane trudnoće može smanjiti rizik od spina bifida-e i drugih defekata živčane cijevi u novorođenčadi. Smanjen rizik je primijećen i kod žena koje su već imale trudnoću pogođenu defektima neuralne cijevi. Jedno novije istraživanje provedeno u Mađarskoj, koje je obuhvatilo 14000 trudnica, ukazalo je na važnost dodavanja folne kiseline prehrani i u posljednjem tromjesečju trudnoće. Istraživanje je objavljeno u časopisu European Journal of Obstetrics & Gynecology and Reproductive Biology u veljači 2010. godine. Iako je uzimanje folne kiseline neophodno u prvom tromjesečju – razdoblju kada se razvija živčani sustav djeteta kako bi se prevenirao nastanak oštećenja neuralne cijevi (najčešće spina bifida i anencefalija), mađarski znanstvenici tvrde kako i u zadnjem trimestru folna kiselina ostvaruje svoje blagodati. Istraživanje je, naime, pokazalo kako je svakodnevno uzimanje folne kiseline rezultiralo 7 posto smanjenim rizikom od prijevremenog poroda, a pronađena je i pozitivna korelacija s porodnom težinom. Gdje se nalazi folna kiselina? Najbolji izvori folne kiseline su: teleća jetra, leća, pšenične klice, šparoge, špinat, grah, raštika, cikla, grašak, brokula, prokulice, avokado, bundeva, cvjetača, mahune, tikvice, banana, celer, kupus, rajčica, limun, paprika, zelena salata, klice. Sadržaj folne kiseline u 1 šalici namirnica u µg Pročitajte više o četvrtom tjednu trudnoće!