TUESDAY, May 10 (HealthDay News) -- Vitamin D supplements for pregnant women may help prevent a respiratory disease called RSV that can lead to pneumonia and other potentially life-threatening illnesses in newborns, Dutch researchers report.
Respiratory syncytial virus (RSV) is the most common cause of pneumonia and inflammation of the lower airways (bronchiolitis) in infants in the United States, according to the U.S. Centers for Disease Control and Prevention. While most children recover, many are hospitalized and develop respiratory problems that persist well into childhood.
"We have no treatment for RSV. The only thing we can do is try to prevent the disease," said lead researcher Dr. Louis Bont, from the department of pediatric infectious diseases at Wilhelmina Children's Hospital and University Medical Center in Utrecht.
One way to prevent RSV is for pregnant women to take supplemental vitamin D, he said. "In fact, there are guidelines that prescribe that," he added.
"If pregnant women do not take vitamin D supplements, they have low vitamin D levels in the umbilical cord blood and then the children have a severely increased risk of RSV," Bont said.
"Intake of vitamin D during late stage of pregnancy is vital to prevent RSV, and probably other respiratory diseases as well," he concluded.
RSV infects about 5 million children in the United States each year. But if women took vitamin D supplements during pregnancy, about 20 percent of those infections in newborns might be prevented, Bont said. "That would be in the magnitude of 1 million cases per year," he said.
Vitamin D has many important functions, Bont explained, noting that "it shapes and matures the immune system." In addition, the vitamin plays a role in helping the respiratory system develop, he added.
The report was published in the May 9 online edition of Pediatrics.
For the study, Bont's team measured the amount of vitamin D in the umbilical cord blood of 156 newborns in the Netherlands.
The researchers found 54 percent of these newborns had insufficient levels of vitamin D. Among these infants, 18 (12 percent) developed RSV in the first year of life.
In fact, infants with low levels of vitamin D were six times more likely to develop RSV, compared with infants who had the highest levels, Bont's group found.
Among the women in the study, only 46 percent said they took supplements containing vitamin D while they were pregnant, the researchers noted.
Bont thinks all pregnant women should be taking vitamin D supplements. In general, they should be getting 400 to 1,000 International Units (IU) a day, he said.
In the study, Bont and other researchers explained that some pregnant women might need up to 4,000 IU a day to achieve the best outcome for their infants. (Experts who make up the U.S. Food and Nutrition Board recommend that pregnant women get at least 600 IU of vitamin D daily and note that they can safely take up to 4,000 IU a day, according to the U.S. Office of Dietary Supplements.)
The cost of prenatal vitamins, which contain vitamin D, is about $9 a month.
What the researchers have shown in this study is an association between vitamin D and preventing RSV. To establish a cause-and-effect relationship, Bont said that randomized trials are needed.
Dr. Andrew Colin, director of the division of pediatric pulmonology at the University of Miami Miller School of Medicine, said this finding could "save the world a humongous amount of money."
Colin noted the recognition of the link between low vitamin D levels and lung diseases has been growing over the years. This is particularly true for asthma. In fact, the increase in the number of asthma cases can, in part, be attributed to low vitamin D levels, he said.
"RSV is a worldwide scourge," Colin said. "Probably the most significant lung disease of infancy is RSV. The bad news about this disease is that quite a few infants who have had RSV infection will develop an asthma-like disease, which can affect their entire childhood," he added.
Colin thinks vitamin D may very well prevent RSV. "If, indeed, boosting the vitamin D in the mothers is going to end up with high vitamin D in babies [and] is going to make a difference, I think it's huge," he said.
This concept needs to be tested, Colin said, but added that he thinks it is fine for pregnant women to take supplemental vitamin D now. "I can't see the downside," he said.
For more information on respiratory syncytial virus (RSV), visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Louis Bont, M.D., Ph.D., department of pediatric infectious diseases, Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands; Andrew Colin, M.D., professor and director, division of pediatric pulmonology, University of Miami Miller School of Medicine; May 9, 2011, Pediatrics, online
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