Here’s an easy way to remember the best sources of this essential B vitamin: think "foliage." Folic acid and its food form, folate, were discovered by researchers who waded through four tons of spinach to isolate enough of it to study. You don’t need to eat four tons of spinach to get all the folate you need in a day. If you have a yen for spinach, about four cups of the raw greens will provide the Daily Value of 400 micrograms. (Like your spinach cooked? You’ll have to eat twice that amount, since up to half of the folate in foods is lost in cooking.) Or you can get a spinach-bowl’s-worth of this nutrient in capsule form.
Genetic Engineering
Folic acid is essential for DNA and RNA synthesis. That means it has to be on hand for your body to make the genetic material—the blueprint—that allows a cell to grow and divide to make more cells. "Folic acid actually helps to make the building blocks, called bases, that are strung together like pearls to form the DNA," says Barry Shane, Ph.D., professor of nutrition and chair of the department of nutritional sciences at the University of California at Berkeley.
RNA is kind of a "working copy" of DNA. Parts of DNA can be copied to RNA when a cell has to make a certain kind of protein, for instance. The RNA then travels to the part of the cell where the protein can be made and hands over the instructions.
"More folic acid is needed for this process when cells are rapidly dividing, as they do during growth and development, and in areas where cells normally have a relatively short life, such as the intestines and blood cells," Dr. Shane says. When folic acid is in short supply, DNA synthesis slows, and cells lose their ability to divide and multiply. That has the potential to create major, body-wide problems. In the blood, for instance, it can cause anemia, a lack of red blood cells. In the intestines, it can create absorption problems. Folic acid deficiency can also be a factor in heart disease. Also, in some cases, when your body is short on this nutrient, it could produce abnormal cells, a condition called dysplasia that can lead to cancer. Low folic acid levels during pregnancy can set the stage for birth defects.
Tired Blood
If folic acid intake is low enough for long enough, you’ll develop megaloblastic anemia. In this form of anemia, "your red blood cells are unable to fully mature, and if you look at them under a microscope, they’re large and egg-shaped," Dr. Shane explains. Your body also produces fewer red blood cells than you need for good health. Normally, cells in the bone marrow crank out red blood cells at the rate of 200 million a minute, but in this case, there’s just not enough folic acid to maintain this pace without producing a lot of duds.
SUPPLEMENTSNAPSHOT
| Folic Acid Also known as: Folate; folacin. May help: Prevent birth defects, including defects of the neural tube, cleft palate, and cleft lip; reverse precancerous cell changes (dysplasia) in the cervix, lungs, or colon; treat megaloblastic anemia, canker sores, depression, gout, and gingivitis. With vitamins B6 and B12 can also lower blood levels of homocysteine to reduce risk of heart attack and prevent intermittent claudication, phlebitis, Alzheimer’s disease, angina, and high blood pressure. Daily Value: 400 micrograms. Who’s at risk for deficiency: People who use the cholesterol-lowering drug cholestryramine (Questran); people with cancer; the elderly, especially if their diets are nutritionally deficient; pregnant women; people recovering from burns; those who have had blood loss, gastrointestinal tract damage, chicken pox, or measles; alcoholics; and smokers. Good food sources: Spinach, lentils, navy beans, pinto beans, and sunflower seeds. Heat and oxidation during cooking and storage can destroy as much as half of the folate in foods, so many food sources don’t provide very much. Cautions and possible side effects: Do not take doses above 1,000 micrograms a day without medical supervision. |
Megaloblastic anemia is most likely to occur during pregnancy, when there is an increased requirement for growth, and in people taking drugs that deplete the body of folic acid, Dr. Shane says. "Most people who develop this sort of anemia have been low on folic acid for months. It is also a fairly common problem in the elderly," he adds.
Cancer Cop
Cancer results from an accumulation, over time, of damage to the DNA. Smoking, exposure to harmful chemicals, frequent exposure to x-rays, and certain viruses can damage a cell’s genetic material. Add the injury of a folic acid shortage to any one of these insults, and "you are turning up the speed of the damage several-fold," explains Patrick Stover, Ph.D., assistant professor of nutritional biochemistry and cell biology at Cornell University in Ithaca, New York.
Folic acid deficiency has been strongly linked to DNA damage in several studies. In one, researchers at the University of California at Berkeley found that even a mild deficiency caused a large increase in the amount of damaged DNA. Other studies have shown a link between folic acid deficiency and dysplasia in the cervix, colon, and lungs.
Healthy Heart Helper
What happens to that steak you devour? In your body, protein from the steak is broken down into bits—amino acids—that your body can disassemble even further, then reassemble to make some urgently needed new amino acids. The amino acids may be strung together again to form new proteins, so that steak may eventually help form cells in your nose. Folic acid helps that happen because it helps to metabolize—break down and reassemble—several amino acids.
In that role, folic acid deficiency may play a part in the development of heart disease. It is needed to transform homocysteine—an amino acid by-product that in high concentrations is toxic to the body—to a more useful form called methionine. "When you don’t have enough folic acid, blood levels of homocysteine rise, and those higher levels are linked with an increased risk of heart disease and stroke," says John Pinto, Ph.D., associate professor of biochemistry at Weill Medical College of Cornell University and director of the nutrition research laboratory at Memorial Sloan- Kettering Cancer Center, both in New York City. "In fact," he says, "the connection seems to be as strong as, if not stronger than, the connection between high cholesterol and heart disease. So this isn’t a mere curiosity. It’s something to pay attention to."
High levels of homocysteine contribute to heart disease in a couple of nasty ways, Dr. Pinto says. They damage the cells lining the blood vessels, creating rough spots that attract cholesterol deposits. Plus, they cause blood to clot more readily at those rough spots. When that happens, the artery-clogging clots begin to set the stage for heart attack or stroke.
"One problem being investigated right now is how much folic acid you need to protect against heart disease," Dr. Pinto says. In one study, people who got five milligrams a day for two weeks had significant drops in homocysteine, especially those whose initial levels were high.
Building Better Babies
To "construct" a baby, a woman’s body has to turn a single fertilized egg into billions of cells, all in nine months. That takes a lot of DNA and RNA—and so it takes a lot of folic acid. "Requirements for folic acid increase in a pregnant woman, both because of the rapid rate of cell growth and division in the fetus and because the woman is making more cells herself," says Joseph Mulinare, M.D., chief of the prevention branch at the birth defects division of the Centers for Disease Control and Prevention in Atlanta. During pregnancy, a woman’s blood volume may increase by as much as 50 percent.
Pregnant women sometimes don’t get enough folic acid. If the shortage isn’t detected and corrected, these moms can have children with birth defects, especially spinal cord and brain problems called neural tube defects. These defects are initiated very early in fetal development, often before a woman knows she is pregnant. "That’s why it’s important to start taking folic acid before you get pregnant," Dr. Mulinare says.
Of course, pregnancy isn’t exactly a preprogrammed event. If you’re a woman who is trying to conceive, though, it’s definitely a smart move to get all you need of this important nutrient. If you’re using a contraceptive and decide to go off it, doctors recommend that you start taking 400 micrograms daily of folic acid three months before you stop using contraception. Then continue the same daily dose for at least three months into the pregnancy.
Figure Out How to Fill Up
Most people get about 200 micrograms of folate a day, about half the Daily Value. With folic acid–fortified foods such as breads and breakfast cereals now on the market, daily intake could increase on average to about 300 micrograms a day, Dr. Mulinare says, possibly leaving a 100-microgram daily deficit. Most over-the-counter multivitamins contain 400 micrograms, and a few super-potency vitamins provide 800 micrograms. "It’s also possible to get supplements that contain only folic acid, usually 400 micrograms," he says.
