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Vol. LXIII, No. 13
June 24, 2011
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Digest

Folic Acid Supplements Not Likely to Affect B12 Deficiency

Exposure to secondhand smoke has a direct, measurable impact on the brain, according to a study funded by the National Institute on Drug Abuse.
Taking folic acid supplements or eating fortified grain products is unlikely to worsen problems related to low levels of vitamin B12, according to researchers at NIH and five other institutions. The finding was reported in the American Journal of Clinical Nutrition.

Taking folic acid supplements or eating fortified grain products is unlikely to worsen problems related to low levels of vitamin B12, according to researchers at NIH and five other institutions in the U.S., Ireland and Norway.

In the U.S., bread, cereal and other enriched flour products have been fortified with folic acid (the synthetic form of the vitamin folate) since 1998. Women with low levels of folate are at increased risk for conceiving a child with birth defects of the brain and spinal cord known as neural tube defects. The number of infants born with these birth defects has fallen since fortified foods were introduced.

Researchers have been concerned that the level of folic acid in fortified grains—needed to reduce women’s risk for conceiving a child with a neural tube defect—might be too high for other people. These concerns stem from earlier studies that found higher rates of anemia and other blood abnormalities in people with low B12 levels who also had high folate levels. The people with low B12 and high folate levels were more likely to have anemia than did people with low B12 levels and normal folate levels.

However, many of these studies were conducted in older people, a group more likely to have difficulty absorbing B12. Researchers were uncertain whether these blood abnormalities were due to the high folate levels or to medical conditions common to older people.

“Our findings are reassuring for people who have low vitamin B12 levels,” said first author Dr. James Mills of NICHD. “We found no evidence that folate could worsen their health problems. Consuming higher amounts of folate does not seem to interfere with the body’s use of vitamin B12 in otherwise healthy individuals.”

Experimental Drug Benefits Patients with Rare Cancer

An experimental drug, cediranib, may benefit patients with a rare, slow-growing cancer called alveolar soft part sarcoma (ASPS), according to results from a clinical trial. The NCI trial showed tumors shrank in more than 50 percent of ASPS patients who were treated with cediranib. These findings were presented at the American Society of Clinical Oncology annual meeting in Chicago on June 6. ASPS accounts for less than 1 percent of soft tissue sarcomas and forms in tissues that connect, support or surround the organs of the body. It is usually diagnosed in children and young adults, developing as a painless mass in the leg or buttock.

XMRV Origins Deciphered, Undermining Claims for Role in Human Disease

Delineation of the origin of the retrovirus known as XMRV from the genomes of laboratory mice indicates that the virus is unlikely to be responsible for either prostate cancer or chronic fatigue syndrome in humans, as has been widely published. The virus arose because of genetic recombination of two mouse viruses. Subsequent infection of lab experiments with XMRV formed the basis of the original association.

Reporting in Science May 31, Dr. Vinay Pathak and his NCI team in collaboration with other researchers, described when and how XMRV arose and explain the original, incorrect association. XMRV stands for xenotropic murine leukemia virus-related virus.

This study is being reported in the same issue of Science as another study of XMRV (Knox et al.) that finds a lack of association between the virus and CFS even in the same patients from a 2009 study. “Taken together, these results essentially close the door on XMRV as a cause of human disease,” said Tufts University School of Medicine professor Dr. John Coffin, a coauthor with Pathak.

Murine leukemia viruses are retroviruses that cause cancers and other diseases in mice. They are divided into different classes, one of which is xenotropic murine leukemia viruses. Although viruses in this class cannot grow in or infect cells from most mice, in the laboratory they can infect cells from other species, including human cells.

XMRV was first reported in samples from a human prostate tumor in 2006, and has been reported to be present in 6 percent to 27 percent of human prostate cancers. Later research reported XMRV in the blood of 67 percent of people with CFS.

Upon careful examination in Pathak’s study, it was shown that initial prostate tumor xenografts did not contain XMRV but later tumors that had been derived from them did, demonstrating that XMRV was not present in the original human tumor as previously supposed. Instead, the virus appears to have infected tumor cells while they were in mice.—compiled by Carla Garnett


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