Vitamin B9, also called folate or folic acid, is one of 8 B vitamins. All B vitamins help the body to convert food (carbohydrates) into fuel (glucose), which is "burned" to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body metabolize fats and protein. B complex vitamins are necessary for healthy skin, hair, eyes, and liver. They also help the nervous system function properly. Folic acid is the synthetic form of B9, found in supplements and fortified foods, while folate occurs naturally in foods.

All the B vitamins are water-soluble, meaning that the body does not store them.

Folic acid is crucial for proper brain function and plays an important role in mental and emotional health. It aids in the production of DNA and RNA, the body's genetic material, and is especially important when cells and tissues are growing rapidly, such as in infancy, adolescence, and pregnancy. Folic acid also works closely with vitamin B12 to regulate the formation of red blood cells and to help iron function properly in the body.

Vitamin B9 works with vitamins B6 and B12 and other nutrients to control blood levels of the amino acid homocysteine. Elevated levels of homocysteine are associated with certain chronic conditions such as heart disease and, possibly, depression and Alzheimer's disease, although the link isn't clear.

Mild folic acid deficiency is fairly common. Alcoholism, irritable bowel syndrome, and celiac disease can cause one to be deficient in this important nutrient. Also, certain medications may lower levels of folic acid in the body. Folic acid deficiency can cause poor growth, tongue inflammation, gingivitis, loss of appetite, shortness of breath, diarrhea, irritability, forgetfulness, and mental sluggishness.

Pregnant women require more folic acid. Lower levels of folic acid during pregnancy are associated with low birth weight and increased risk of neural tube defects including cleft palate, spina bifida, and brain damage. Neural tube defects are birth defects caused by abnormal development of the neural tube, a structure that eventually gives rise to the brain and spinal cord. Since the U.S. Food and Drug Administration (FDA) authorized the addition of folic acid to many grain foods (such as bread and cereal), neural tube defects in the United States have decreased.

Birth Defects

As mentioned, pregnant women who are deficient in folic acid are more likely to have children with birth defects. Pregnant women should get 600 mcg of folic acid per day. Women who plan to become pregnant should make sure to get the recommended 400 mcg per day, since many neural tube defects can occur shortly after conception (before a woman may even know she is pregnant). Prenatal vitamins contain the needed folic acid for pregnant women.

Studies have found that women who take folic acid supplements before conception and during the first trimester may reduce their risk of having children with neural tube defects by 72 - 100%.

Folic acid may also help prevent miscarriage, although the evidence isn't clear.

Heart Disease

Folate may help protect the heart through several methods. First, there is some evidence that getting enough folic acid in your diet can reduce your risk of heart disease, although this evidence is based on population studies and not more definitive clinical trials.

In addition, because folic acid helps control levels of homocysteine in the body, and because homocysteine levels tend to be high in people with heart disease, some researchers theorize that lowering levels of homocysteine may help prevent heart disease, heart attack, and stroke. Collectively, many studies indicate that patients with elevated levels of the amino acid homocysteine are roughly 1.7 times more likely to develop coronary artery disease (which can lead to a heart attack) and 2.5 times more likely to suffer from a stroke than those with normal levels. However, researchers don't yet know whether high levels of homocysteine actually cause heart disease, or whether something else causes heart disease as well as high homocysteine levels. Until more is known, researchers aren't sure whether lowering homocysteine levels has any effect on heart disease.

The American Heart Association recommends that, for most people, an adequate amount of folate and these other B vitamins be obtained from the diet, rather than taking extra supplements. However, if you have high levels of homocysteine or a history (or family history) of heart disease, ask your doctor whether folic acid supplements would be right for you.

Age-related Hearing Loss

One study suggests that folic acid supplements help slow the progression of age-related hearing loss in elderly people with high homocysteine levels and low folate in their diet. It isn't known whether healthy seniors would benefit.

Depression

Some studies show that 15 - 38% of people with depression have low folate levels in their bodies, and those with very low levels tend to be the most depressed. Low levels of folic acid have also been associated with a poor response to antidepressants. However, more research is needed to understand the link; it appears that folic acid may help enhance the effect of antidepressants, at least in some people, but folic acid itself is not a replacement for antidepressants.

Cancer

Folic acid appears to protect against the development of some forms of cancer, particularly cancer of the colon, as well as breast, cervical, pancreatic, and stomach. However, this evidence is based on population studies that show people who get enough folate in their diet have lower rates of these cancers. It is not clear exactly how folate might help prevent cancer. Some researchers speculate that folic acid keeps DNA (the genetic material in cells) healthy and prevents mutations that can lead to cancer. There is no evidence that taking folic acid supplements helps prevent cancer. The best course of action is to make sure you eat a balanced diet with enough folate, which will help protect you against a number of diseases.

Low dietary intake of folate may increase the risk of developing breast cancer, particularly for women who drink alcohol. Regular use of alcohol (more than 1 ½ to 2 glasses per day) is associated with increased risk of breast cancer. One large study, involving over 50,000 women who were followed over time, suggests that adequate intake of folate may lessen the risk of breast cancer associated with alcohol.

Rich sources of folate include spinach, dark leafy greens, asparagus, turnip, beets, and mustard greens, Brussels sprouts, lima beans, soybeans, beef liver, brewer's yeast, root vegetables, whole grains, wheat germ, bulgur wheat, kidney beans, white beans, lima beans, mung beans, salmon, orange juice, avocado, and milk. In addition, all grain and cereal products in the U.S. are fortified with folic acid.

Vitamin B9 is found in multivitamins (including children's chewable and liquid drops) and B complex vitamins, or is sold individually. It is a good idea to take folic acid as part of or along with a multivitamin because other B vitamins are needed for its activation. It is available in a variety of forms, including tablets, softgels, and lozenges.

Most people (except pregnant women) should be able to get adequate folic acid from their diet.

It is important to check with a knowledgeable health care provider before taking folic acid supplements or giving them to a child.

Daily recommendations for dietary folic acid are listed below:

Pediatric

• Infants under 6 months: 65 mcg (adequate intake)
• Infants 7 to 12 months: 80 mcg (adequate intake)
• Children 1 - 3 years: 150 mcg (RDA)
• Children 4 - 8 years: 200 mcg (RDA)
• Children 9 - 13 years: 300 mcg (RDA)
• Adolescents 14 - 18 years: 400 mcg (RDA)

Adult

• 19 years and older: 400 mcg (RDA)
• Pregnant women: 600 mcg (RDA)
• Breastfeeding women: 500 mcg (RDA)

Amounts recommended for heart disease range from 400 to 1,200 mcg. However, high levels of folate can mask a vitamin B12 deficiency, and should be taken only under a doctor's supervision.

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

At the recommended daily allowance, side effects from folic acid are rare. Very high doses can cause stomach problems, sleep problems, skin reactions, and seizures.

Anyone taking more than 800 mcg of folic acid should talk to their doctor, because folic acid can mask an underlying vitamin B12 deficiency, which can cause permanent damage to the nervous system. In fact, taking any one of the B complex vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, it is generally important to take a B complex vitamin with any single B vitamin.

If you are currently being treated with any of the following medications, you should not use folic acid supplements without first talking to your health care provider.

Antibiotics, Tetracycline -- Folic acid should not be taken at the same time as the antibiotic tetracycline because it interferes with the absorption and effectiveness of this medication. Folic acid either alone or in combination with other B vitamins should be taken at different times from tetracycline. (All vitamin B complex supplements act in this way and should therefore be taken at different times from tetracycline.)

Drugs That Lower Levels of Folic Acid -- These drugs may interfere with the body's absorption of folate, and may mean you need to take a folic acid supplement. Talk to your doctor first.

• Antacids, H2 blockers, proton pump inhibitors
• Bile acid sequestrants
• Carbamazepine
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Sulfasalazine
• Triamterene

When taken for long periods of time, these medications, as well as other anti-inflammatory medicines, can increase the body's need for folic acid.

Birth Control Medications, Anticonvulsants, and Cholesterol-lowering Medications -- Birth control medications, anticonvulsants for seizures (namely, phenytoin and carbamazapine), and cholesterol-lowering medications (namely, bile acid sequestrants, including cholestyramine, colestipol, and colesevelam) may reduce the levels of folic acid in the blood as well as the body's ability to use this vitamin. Extra folate when taking any of these medications may be recommended by your health care provider. When taking bile acid sequestrants for cholesterol, you should take folate at a different time of day.

Methotrexate -- Methotrexate, a medication used to treat cancer, rheumatoid arthritis (RA), and psoriasis, reduces the amount of folic acid in the body. People who take methotrexate for RA or psoriasis may be prescribed higher doses of folic acid, which helps reduce the side effects of methotrexate. People taking methotrexate for cancer, however, should avoid folic acid supplements unless directed by their doctor, because folic acid may interfere with methotrexate's effects on cancer.

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