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Wednesday, September 8, 2004, 12:00 a.m. EDT
New Research Suggests Link Between Maternal Diet and Childhood Leukemia Risk
A new study suggests that eating more vegetables, fruit and protein before pregnancy may lower the risk of having a child who develops leukemia, the most common childhood cancer in the United States.
"This is the first time researchers have conducted a systematic survey of a woman's diet and linked it to the risk of childhood leukemia," said Dr. Kenneth Olden, director of the National Institute of Environmental Health Sciences (http://www.niehs.nih.gov), the federal agency that funded the study. NIEHS is a component of the National Institutes of Health (http://www.nih.gov) .
The study was conducted by researchers at the University of California, Berkeley, and the study results are published in the August 2004 issue of Cancer Causes and Control.
Researchers compared 138 women who each had a child diagnosed with acute lymphoblastic leukemia (ALL) with a control group of 138 women whose children did not have cancer. The children of all the women in the study were matched by sex, age, race, and county of residence at birth.
After comparing the women's diets in the 12 months prior to pregnancy, researchers found that the higher the intake of vegetables, fruit and foods in the protein group, the lower the risk of having a child with leukemia.
One of the more surprising results of the study is the emergence of protein sources, such as beef and beans, as a beneficial food group in lowering childhood leukemia risk. "The health benefits of fruits and vegetables have been known for a long time," said principal investigator Gladys Block, professor of epidemiology and public health nutrition at U.C. Berkeley. "What we found in this study is that the protein foods group is also very important."
The researchers looked further and found that glutathione was the nutrient in the protein group with a strong link to lower cancer risk. Glutathione is an antioxidant found in both meat and legumes, and it plays a role in the synthesis and repair of DNA, as well as the detoxification of certain harmful compounds.
Within the fruit and vegetable food groups, certain foods - including carrots, string beans and cantaloupe - stood out as having stronger links to lower childhood leukemia risk. The researchers point to the benefits of nutrients, such as carotenoids, in those foods as potential protective factors. National guidelines recommend that people eat at least five servings of fruits and vegetables every day, and two to three servings of foods from the protein group.
"Fetal exposure to nutritional factors has a lot to do with what mom eats," said Christopher Jensen, a nutritional epidemiologist at U.C. Berkeley and lead author of the paper. "These findings show how vital it is that women hoping to get pregnant, as well as expectant moms, understand that critical nutrients in vegetables, fruit and foods containing protein, such as meat, fish, beans and nuts, may protect the health of their unborn children."
The few studies that have been conducted on maternal diet and childhood cancer risk looked only at specific foods or supplements, and results have been mixed. This study is the first attempt to capture a woman's overall dietary pattern - using a 76-food-item questionnaire - and its relationship to the development of leukemia in a child. Researchers also studied the use of vitamin supplements, but did not find a statistically significant link to childhood leukemia risk.
A growing number of scientists believe that genetic changes linked to cancer later in life begin in the womb. "It goes back to the old saying to expectant mothers, 'You're eating for two,'" said co-author Patricia Buffler, U.C. Berkeley professor of epidemiology and head of the federally funded Northern California Childhood Leukemia Study. "We're starting to see the importance of the prenatal environment, since the events that may lead to leukemia are possibly initiated in utero. Leukemia is a very complex disease with multiple risk factors. What these findings show is that the nutritional environment in utero could be one of those factors."
Customized Program Reduces Asthma Symptoms in Inner-City Children
A program that targets allergens and tobacco smoke in the home resulted in fewer asthma symptoms in children participating in the intervention than in those who were not, according to a new study sponsored by the National Institutes of Health (NIH) in seven metropolitan areas nationwide. Children taking part in the intervention had 21 fewer days of asthma symptoms over the one-year course of intervention.
The study-co-funded by the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Environmental Health Sciences (NIEHS), two NIH Institutes-appears in the September 9th issue of The New England Journal of Medicine.
"The burden that childhood asthma places on our society is enormous," says Anthony S. Fauci, M.D., director of NIAID. "For the millions of children living with asthma, this important research demonstrates that taking practical steps can achieve long-term benefits in the form of better quality of life, fewer emergency room visits and lower healthcare costs."
"These study results are exciting because they show that changes made in the home environment can produce a reduction in symptoms comparable to that achieved with asthma inhalers," notes Kenneth Olden, Ph.D., director of NIEHS.
Asthma, a chronic lung disease characterized by coughing, wheezing and difficulty breathing, affects roughly 20 million Americans. Children who live in the inner city-in particular African-American and Hispanic children-suffer disproportionately from the disease. Increased asthma symptoms in this population may stem from exposure to high levels of multiple indoor allergens and tobacco smoke.
More than 900 children ages 5 to 11 with moderate to severe asthma participated in the study. Each participant had to be allergic to at least one common indoor environmental allergen, such as cockroach allergen or house dust mite allergen. The children, most of whom were African American or Hispanic, lived in low-income sections of seven major metropolitan areas-the Bronx, Boston, Chicago, Dallas, Manhattan, Seattle/Tacoma and Tucson. Once accepted into the study, they were randomly assigned to either the intervention group or a control group.
Based on the child's sensitivity to the selected indoor allergens and evidence of exposures at home to known asthma triggers, investigators designed an individualized environmental intervention, carried out by the child's mother or another caretaker. The intervention focused on educating the family about ways to reduce or eliminate all allergens to which the child was allergic, as well as to reduce exposure to tobacco smoke, and motivating them to pursue these steps. The investigators developed separate interventions tailored to tobacco smoke and to the following allergens-house dust mite, cockroach, pet, rodent and mold.
In addition, families were given specific allergen-reducing measures, such as allergen-impermeable covers for children's bedding and air purifiers with HEPA (high efficiency particulate air) filters, to be placed in key locations within their homes, including the children's bedrooms. Cockroach extermination visits were provided for children who were allergic to cockroach allergens. During the first year of the study, the investigators conducted educational home visits with the families in the intervention group. Throughout the yearlong study and the one-year follow-up, researchers closely monitored all participants' asthma symptoms and home allergen levels.
Children who participated in the intervention had significantly fewer asthma symptoms compared with those in the control group: an average of 21 fewer days of symptoms in the first year and an average of 16 fewer days during the second, or follow-up, year. In addition, the benefits of the intervention occurred rapidly: Investigators noted significant reductions in symptoms just 2 months after the study began.
The levels of cockroach and dust mite allergens in the children's bedrooms in the intervention group were substantially lower than in the control group. Furthermore, the researchers noted a direct correlation between allergen levels and asthma symptoms for the children in the intervention group: The greater the drop in cockroach or house dust mite allergen levels, the greater the reduction in asthma symptoms, suggesting that the allergy-reducing measures made the difference.
Most previous environmental intervention studies focused on controlling a single allergen or tobacco smoke, and met with limited success.
"Children with asthma are usually sensitive to more than one allergen," says Daniel Rotrosen, M.D., director of NIAID's Division of Allergy, Immunology, and Transplantation. "By taking a multifaceted, home-based approach, this new study demonstrates the promising results families can achieve when they incorporate the recommended practices of allergen reduction into their everyday lives."
This project is part of the Inner City Asthma Study, a cooperative multicenter initiative comprising seven asthma study centers across the country and a statistical center. The principal investigators are Wayne J. Morgan, M.D., University of Arizona College of Medicine, Tucson, first author on the paper; Ellen F. Crain, M.D., Ph.D., Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, NY; Richard Evans III, M.D., Children's Memorial Hospital, Chicago, IL; Rebecca S. Gruchalla, M.D., Ph.D., University of Texas Southwestern Medical Center at Dallas, TX; Meyer Kattan, M.D., Mount Sinai School of Medicine, New York, NY; Herman Mitchell, Ph.D., Rho, Inc., Chapel Hill, NC; George T. O'Connor, M.D., Boston University School of Medicine, Boston, MA; and James Stout, M.D., University of Washington School of Medicine and Public Health, Seattle, WA.
NIAID and NIEHS are components of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose and treat infectious diseases such as HIV/AIDS and other sexually transmitted infections, influenza, tuberculosis, malaria and illness from potential agents of bioterrorism. NIAID also supports research on transplantation and immune-related illnesses, including autoimmune disorders, asthma and allergies. NIEHS conducts and supports research to reduce the burden of human illness and dysfunction from environmental causes by understanding environmental factors, individual susceptibility and age, and by discovering how these influences interrelate.
New Research Shows Air Pollution Can Reduce Children's Lung Function
Children who live in polluted communities are five times more likely to have clinically low lung function-less than 80 percent of the lung function expected for their age. New data from the Children's Health Study suggests that pollutants from vehicle emissions and fossil fuels hinder lung development and limit breathing capacity for a lifetime.
The study was funded by the National Institute of Environmental Health Sciences (NIEHS) (http://www.niehs.nih.gov/), one of the National Institutes of Health (http://www.nih.gov/) , the California Air Resources Board and the Hastings Foundation. The results of the study, conducted by researchers at the University of Southern California Keck School of Medicine, are published in this week's issue of the New England Journal of Medicine.
"This is the longest study ever conducted on air pollution and children's health,"said Dr. Kenneth Olden, director of NIEHS. "It shows that current levels of air pollution have adverse effects on lung development in children between the ages of 10 and 18."
Each year, pulmonary function data were collected from 1,759 children as they progressed from 4th grade to 12th grade. The researchers also tracked levels of air pollutants like nitrogen dioxide, acid vapor, elemental carbon, and particulate matter in the 12 Southern California communities where the children lived. The study encompassed some of the most polluted areas in the greater Los Angeles basin, as well as several less-polluted communities outside the Los Angeles area.
Over the eight year period, researchers found that children living in the most polluted communities had significant reductions in their "forced expiratory volume" -- the volume of air that can be exhaled after taking a deep breath -- as compared to children living in communities with cleaner air.
In healthy people, lungs grow to full capacity during the teenage years, but typically stop growing at age 18. Then, lung capacity gradually declines. Adults begin to lose lung function by 1 percent each year after age 20.
"Lung development in teenagers determines their breathing capacity and health for the rest of their lives," said John Peters, M.D., Hastings Professor of Preventive Medicine at the Keck School of Medicine. "The potential long-term effects of reduced lung function are alarming. It's second only to smoking as a risk factor for mortality. As lung function decreases, the risk of respiratory disease and heart attacks increases."
Deficits in lung function are associated with other short- and long-term effects. "If children or young adults with low lung function were to have a cold, they might have more severe lung symptoms, or wheezing," says W. James Gauderman, Ph.D., associate professor of preventive medicine at the Keck School and lead author on the study. "They may have a longer disease course, while children with better lung function may weather it much better."
Researchers are unsure how air pollution may retard lung development. Gauderman believes chronic inflammation may play a role, with air pollutants irritating small airways on a daily basis. Scientists also suspect that air pollutants might dampen the growth of alveoli, tiny air sacs in the lungs.
The research team will continue to follow the study participants into their early 20s, when their lungs will be fully mature. They want to find out whether the participants will experience respiratory symptoms, and if those who moved away from a polluted environment will show some improvement in lung function.
This research is part of the larger Children's Health Study, an ongoing study that was started in 1993. The study is the longest ever undertaken on the association between air pollution and children's health.