Folic acid may reduce some childhood cancers
Folic acid fortification of foods may reduce the incidence of the most common type of kidney cancer and a type of brain tumors in children, finds a new study by Kimberly J. Johnson, PhD, assistant professor at the Brown School at Washington University in St. Louis, and Amy Linabery, PhD, postdoctoral fellow at the University of Minnesota.
Incidence reductions were found for Wilms’ tumor, a type of kidney cancer, and primitive neuroectodermal tumors (PNET), a type of brain cancer.
Since 1998, the U.S. Food and Drug Administration has mandated fortification of foods with folic acid because earlier studies show that prenatal consumption of folic acid significantly reduces the incidence of neural tube defects in babies.
“Our study is the largest to date to show that folic acid fortification may also lower the incidence of certain types of childhood cancer in the United States,” Johnson says.
The study, published in the current issue of Pediatrics, examined the incidence of childhood cancer pre- and post-mandated folic acid fortification.
“We found that Wilms’ tumor rates increased from 1986 to 1997 and decreased thereafter, which is an interesting finding since the downward change in the trend coincides exactly with folic acid fortification,” Johnson says.
“PNET rates increased from 1986 to 1993 and decreased thereafter. This change in the trend does not coincide exactly with folic acid fortification, but does coincide nicely with the 1992 recommendation for women of childbearing age to consume 400 micrograms of folic acid daily.”
Folic Acid
Other common name(s): folate, folacin, vitamin B9
Scientific/medical name(s): pteroylglutamic acid
Folic acid, or folate, is a B vitamin found in many beans, grains, fortified breakfast cereals, pasta, and green vegetables. It helps the body build and maintain DNA and is important in helping the body make new cells, especially red blood cells.
Low levels of folic acid in the blood have been linked with higher rates of colorectal cancer and some other types of cancer, as well as with certain birth defects. It is not clear whether consuming recommended (or higher) amounts of folic acid - from foods or in supplements - can lower cancer risk in some people. These issues are being studied. High doses of folic acid can interfere with the action of some chemotherapy drugs, such as methotrexate.
How is it promoted for use?
Folic acid, or folate, is a B vitamin. It is promoted mainly as part of a healthy diet to reduce the risk of birth defects of the brain and spine (such as underdeveloped brain and spina bifida or “open spine”). Some people believe that it helps reduce the risk of certain types of cancer and heart disease. It may also be promoted for prevention of Alzheimer’s disease, high blood pressure, and chronic fatigue syndrome.
Study authors used the 1986-2008 data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER), which has collected information on cancer cases in various areas of the U.S. since 1973. The study involved 8,829 children, from birth to age four, diagnosed with cancer.
“Declines in Wilms’ tumors and PNETs in children were detected by multiple analyses of the data,” Johnson says.
The first studies that looked at the link between folic acid and cancer took place in the 1960s and 1970s. After noting that cells from the cervix in folate-deficient women looked a lot like cells showing early signs of cancer, researchers began to suspect a link between the two. By the 1990s, studies looking at large groups of people found that certain types of cancer, such as cervical and colorectal cancer, were linked to lower blood levels of folic acid.
The importance of folic acid in preventing birth defects of the brain and spine led the Food and Drug Administration (FDA) to require that grain-based foods, cereals, and dietary supplements be enriched with folate starting in 1998. These neural tube defects are a type of birth defect in which the brain, spinal cord, or their protective coverings do not fully develop. These defects occur early in fetal development, often starting before the woman even knows she is pregnant. Spina bifida is one of the more common types of neural tube defects.
“Importantly, the reduced rates of Wilms’ tumors also were found in a smaller study conducted in Ontario, Canada, that was published in 2011.
“More research is needed to confirm these results and to rule out any other explanations.”
If folate/folic acid somehow caused cancer, it would have to be the rest of the molecule that is the problem. But most research shows that folic acid/folate prevents cancer. It is well-known that persons eating plant-based diets have a significantly lower risk of cancer. In addition to providing nutrients, eating more vegetation means more fiber and less constipation, valuable for preventing colon cancer. Herbivorous animals are definitely not constipated. Ask any dairy farmer, and you can start with me: many years ago, I used to milk 120 cows twice daily. When you walk behind Bossy, look out.
As for lung cancer, the research accusing folic acid also happens to show that 94% of the study subjects who developed lung cancer were either current or former smokers. Smoking causes cancer. Animals do not smoke. But they do eat a lot of foliage, either by grazing on greens or gorging on guts.
Both studies claiming that folic acid causes cancer were published in the Journal of the American Medical Association, which also contains a large amount of pharmaceutical advertising. JAMA is among the journals that peer-reviewed research has shown to be biased against vitamins due to vested interests.
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References:
(1) Folic acid, B12 may increase cancer risk. - http://url.health.am/803/
(2) High doses of folic acid may increase colon cancer risk. - http://url.health.am/804/
(3) Pharmaceutical advertising biases journals against vitamin supplements. Original study: Kemper KJ, Hood KL. Does pharmaceutical advertising affect journal publication about dietary supplements? BMC Complement Altern Med. 2008 Apr 9;8:11. Full text at - http://url.health.am/805/
Julie A. Ross, PhD, professor and director of the Division of Pediatric Epidemiology & Clinical Research in the Department of Pediatrics at the University of Minnesota, was a study co-author.
Johnson notes that one concern countries face as they are deciding whether or not to fortify foods to reduce neural tube defects in newborns is the possibility that fortification may cause unintended harm, such as causing new cancers or pre-cancerous lesions.
Folic Acid and Prostate Cancer
The current study included 643 men originally recruited for a much larger study designed to determine if taking aspirin and a folic acid supplement could reduce the incidence of colon polyps.
The men were randomly assigned to placebo or supplements with daily low-dose aspirin and 1 milligram of folic acid daily - two and a half times the recommended daily dose of the vitamin for men and for women who are not pregnant or nursing.
Aspirin alone was found to have no significant effect on prostate cancer incidence, but taking folic acid was found to increase the risk for prostate cancer by 163%.
The analysis joins a growing number of studies suggesting that nutritional supplements are of no benefit for preventing cancer.
In an accompanying editorial, two cancer and nutrition experts concluded that “the prospects for cancer prevention through micronutrient supplementation have never looked worse.”
Large trials have shown no protective benefit in people taking multivitamins, selenium, beta-carotene, and vitamins E, C, D, B6, and B12.
Beta-carotene, taken in high doses, has even been shown to promote lung cancers in heavy smokers.
“The primary lesson from our experience in the nutritional prevention of cancer is that it is not simple,” write Alan R. Kristal, MD, of Seattle’s Fred Hutchinson Cancer Research Center and Scott Lippman, MD, of the University of Texas M.D. Anderson Cancer Center.
The study and editorial appear in the March 18 issue of the Journal of the National Cancer Institute.
“Here, we are showing that folic acid fortification does not appear to be increasing rates of childhood cancers, which is good news,” she says.
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Kimberly Johnson
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314-935-9154
Washington University in St. Louis