House CallJune/July 2010 Issue

Research Roundup: Vitamin D, Obesity, & More!

The latest medical news for people with allergies and food sensitivities

Playing outdoors is a great way to help your child's body make vitamin D, an essential nutrient linked to overall wellness.

Playing outdoors is a great way to help your child's
body make vitamin D, an essential nutrient linked
to overall wellness.

A Vital Vitamin

Vitamin D has been getting a lot of press recently for its role in keeping us healthy and potentially protecting us from a number of chronic conditions, including asthma. Researchers from the National Jewish Medical Center in Denver recently carried out two studies of vitamin D’s role in human health. One, presented at the American Academy of Allergy, Asthma & Immunology annual conference in New Orleans in February, found that asthma in kids was linked with lower vitamin D levels. In the study of 99 children, 56 percent had insufficient levels of vitamin D in their blood (defined as less than 30 nanograms/milliliter). Among asthmatics, the lower the level of vitamin D, the more likely the kids were taking an inhaled corticosteroid. The second study looked at data from 54 adults with asthma and found that higher levels of vitamin D were linked to better lung function; study subjects with insufficient levels experienced more airway reactivity and less response to steroid medication. Whether taking supplements might improve asthma symptoms or response to medication was beyond the scope of both studies.

In another study, researchers with the Harvard School of Public Health looked at data from over 35,000 nurses whose mothers completed questionnaires about their diet during pregnancy. The team found that the women whose mothers had the highest intake of vitamin D during pregnancy had a 45 percent lower risk of developing multiple sclerosis than women whose mothers had the lowest intake. The results were presented at the American Academy of Neurology annual meeting in Toronto.

In addition to sun exposure, which helps the body make vitamin D, food sources include fortified milk (and some soy and rice milks—check the label), cod liver oil, salmon and mackerel.

Chronic Conditions in Kids

We've heard about rising obesity rates, but there may be other conditions plaguing our kids, according to a study published in the February 17 issue of the Journal of the American Medical Association. The prevalence of chronic health conditions—defined in the study as obesity, asthma, other physical conditions and behavior/learning problems—rose from almost 13 percent in 1994 to 26.6 percent in 2006. The study looked at three groups of children, who were between ages 2 and 8 in 1988, 1994 and in 2000, for a total of 5,001 subjects. Researchers found not only a high rate of chronic conditions overall, but that prevalence increased with each subsequent group of kids. Male, Hispanic and black children were most likely to have a chronic condition. The rate of maternal obesity, which rose with each group, was linked with a higher rate of chronic illness in children. The study also showed that, for many kids, a chronic condition isn't necessarily permanent; fluctuations occur due to new treatments, lifestyle changes and the normal dynamic of childhood growth and development. The authors write that the findings underscore the benefits of continuous, comprehensive health services for all children to help those with chronic conditions get better and to prevent new cases.

BPA Linked to Heart Disease

Bisphenol-A, the synthetic chemical used in some plastic bottles, aluminum can linings, shower curtains and other items, is the subject of two new studies. Researchers at the University of Texas Medical Branch at Galveston found in mice that a mother's exposure to BPA before and during pregnancy and during lactation led to key signs of asthma in the offspring at much higher rates than unexposed mice. The scientists aren't sure precisely why but they believe it may be BPA's suspected role as an endocrine disruptor, that is, a substance that blocks or mimics naturally occurring hormones and interferes with normal functioning. In this case, the chemical may interfere with immune system development, leading to higher rates of asthma. The work was published in the February issue of Environmental Health Perspectives.
In the United Kingdom, researchers compared 2003/04 and 2005/06 data from a large U.S. health and nutrition study. From the 2003/04 data, the team found a link between increased urinary BPA concentrations and coronary heart disease, diabetes and elevated liver enzymes in adults. Urinary concentrations of BPA were lower in the 2005/06 data, but higher amounts were again linked to heart disease. More studies to clarify the mechanisms behind the links are “urgently needed,” the authors conclude. The work was published in PLoS ONE in January.  
To reduce exposure to BPA, rinse canned fruits and vegetables before heating and eating, and opt for glass baby bottles and stainless steel water bottles (without a plastic liner), as well as glass or ceramic microwave dishes.

Feel-Good Hormone and Autism

Oxytocin, sometimes referred to as the 'love' or 'cuddle' hormone, promotes lactation, as well as bonding and attachment. Studies have found that people with autism tended to have lower levels of oxytocin in their blood, so researchers at the Centre de Neuroscience Cognitive in Lyon, France, wondered whether administering oxytocin might improve social behavior in a small group of people with high-functioning autism or Asperger syndrome. They found that all 13 subjects who received a nasal spray containing the hormone could distinguish among players in a ball-toss computer game, showing a preference for the most cooperative partners. Participants who inhaled the placebo spray showed no preference. When shown photographs of faces in another exercise, the participants who inhaled the hormone looked at the eyes more often than those who received the placebo. A lot more research is needed to better understand the effects, but the findings hint that oxytocin may one day help improve some of the social behaviors of children with autism.

Autism and Parental Age

Having kids at an older age is a known risk factor for autism in children, but whether the age of the mother or father, or both, plays more of a role hasn't been conclusively shown, say authors of a new study. Researchers at the University of California at Davis published an article in the February issue of Autism Research that reports that mom's increasing age consistently ups the risk of autism but an older father raises the risk only when mom is under 30. They also estimate that the trend toward later childbearing contributed an approximate 4.6 percent increase in autism cases in California in the 1990s, the period from which data was analyzed.

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