May 15, 2009
NIH Podcast Episode #0084
Balintfy: Welcome to the 84th episode of NIH Research Radio with news about the ongoing medical research at the National Institutes of Health—the nation's medical research agency. I'm your host Joe Balintfy, and coming up in this episode: reports for both women and men. We'll hear how it's important for women to live a healthy lifestyle, and how men don't necessarily need aggressive prostate-cancer screening. We'll also have an in-depth interview about the risks of pre-diabetes. But first, how low-levels of vitamin B-12 in women may increase the risk for birth defects. That's next on NIH Research Radio.
(BREAK FOR PUBLIC SERVICE ANNOUNCEMENT)
Low Levels of Vitamin B12 May Increase Risk for Neural Tube Defects
Balintfy: Children, born to women who have low blood levels of vitamin B-12 shortly before and after conception, may have an increased risk of a neural tube defect, a devastating birth defect. Dorie Hightower reports on some recent analysis.
Hightower: A new study shows that babies born to women who have low levels of vitamin B12 may have an increased risk of a neural tube defect, a class of birth defects affecting the brain and spinal cord. Dr. James L. Mills of the National Institute of Child Health and Human Development explains that the brain and the spinal cord are formed when a portion of the embryo folds into a tube.
Mills: And when that folding fails to be completed, and doesn't close, then you can get a major defect in either the brain or the spinal cord. And these are both very devastating defects.
Hightower: One type of defect, spina bifida, can cause partial paralysis and the other is a fatal defect in which the brain and skull are severely underdeveloped. Dr. Miller says a major discovery a few years ago was that a lot of neural tube defects could be prevented by taking folic acid.
Mills: And B12 is very closely related to folic acid biochemically, and they are involved in one key reaction. And it's been shown several times previously that people who have children with neural tube defects have lower vitamin B12 levels during pregnancy. So we wanted to pursue that, and find out just how high a level of B12 you needed to be protected from that risk.
Hightower: Dr. Mills says the risk, or incidence rate for neural tube defects is about one per 2,000 live births.
Mills: Now, it used to be one per thousand, and folic acid fortification of food has lowered the rate dramatically.
Hightower: For this study, NIH scientists collaborated with researchers in Ireland, a country with a high rate of neural tube defects.
Mills: In fact, they call it "The Curse of the Celts," there, and it's probably partially genetic, and partially because of diet. So we have been doing research there, because it's an area where they have a lot of people with the problems, and it enabled us to find women who were not exposed to a lot of supplements that contained either folic acid or B12.
Hightower: Dr. Mills points out that the U.S. Public Health Service recommends that all women of childbearing age consumer 400 micrograms of folic acid each day, ensuring adequate stores of the vitamin in the event of an unintended pregnancy. He emphasizes the importance of B12 as well.
Mills: The point that we're making in our study, that's new, is that women also should be aware of the fact that they need adequate B12. And two groups of women are at risk: those who are vegans, who may not be getting B12 in their diets; and women who have an absorption problem, any gastrointestinal problem that can interfere with vitamin absorption. And their physician should be able to tell them if they are at risk.
Hightower: For more information about neural tube defects and this study, visit the NICHD website at www.nichd.nih.gov. This is Dorie Hightower, National Institutes of Health, Bethesda, Maryland.
First Sister Study Results Reinforce the Importance of Healthy Living
Balintfy: In addition to taking vitamin B-12, women may also want to maintain a healthy weight and lower their perceived stress. Those who do may be less likely than obese and stressed women to have chromosome changes associated with aging. This is according to a pilot study that was part of the long-term Sister Study. The Sister Study is looking at the environmental and genetic characteristics of women whose sisters had breast cancer. It hopes to identify factors associated with developing breast cancer. But two recent papers show that factors such as obesity and perceived stress may accelerate the aging process.
Sandler: So our study was focused on a marker called telomere length.
Balintfy: Dr. Dale Sandler is chief of the Epidemiology Branch at the National Institute of Environment Health Sciences and principal investigator of the Sister Study.
Sandler: This study was a pilot effort to help us better understand the relationships between these various factors that have been linked to breast cancer risk and some biological markers of genetic changes.
Balintfy: She explains that telomeres are the repeating DNA sequences at the ends of a person's chromosomes.
Sandler: These telomeres, these caps at the end of the chromosomes, get shorter and shorter. And at some point, they get so short that the chromosome dies. The shortening of the telomeres with age can also be associated with changes in the genes, so the genes are no longer protected.
Balintfy: Dr. Sandler adds that while there is concern that shortening telomeres might also be associated with increased risk for cancer, her study was focused on the changes associated with obesity and perceived stress.
Sandler: What we found is that women who have good coping skills, even though they have high stress, and women who maintain a healthy weight over their lifetime, do not show the same level of changes in their telomere length than women who are obese for their entire life or who have a higher level of stress.
Balintfy: This research, combined with other studies, suggests that lifelong obesity and stress may be associated with an acceleration of the aging process.
Sandler: And that's consistent with other studies that have shown that chronic stress is associated with shorter telomeres or that shorter telomeres are associated with an increased risk for chronic diseases such as cardiovascular disease.
Balintfy: Dr. Sandler emphasized that this is a small pilot study, and although consistent with other reports in the literature, it is preliminary. These are some of the first findings coming out of the Sister Study, which is just completing its enrollment of 50,000 women aged 35-74. For more on these results, visit www.niehs.nih.gov. For more about the Sister Study, visit www.sisterstudy.org.
U.S. Cancer Screening Trial Shows No Early Mortality Benefit from Annual Prostate Cancer Screening
Balintfy: Now from women to men . . . Six annual screenings for prostate cancer led to more diagnoses of the disease, but no fewer prostate cancer deaths. This is according to a major new report from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, which is a 17-year project of the National Cancer Institute. The PLCO was designed to provide answers about the effectiveness of cancer screening, and is looking to see if screening for those cancers can help to lower mortality. Results from a report appear online in a recent issue of the New England Journal of Medicine.
Berg: This particular report focused only on prostate cancer.
Balintfy: Dr. Christine Berg is the National Cancer Institute leader of the PLCO trial and senior author of the study.
Berg: And the straightforward analysis shows that at seven years of follow-up there was no decrease in death in the group that got actively screened compared to the group that got screened by their local physicians. However, there were 500 more cancers found. So, we still saw 50 deaths in the actively screened group, 44 deaths in the less-actively screened group, but we had 2,800 cancers in the actively screened group and 2,300 cancers in the less-actively screened group, so detecting 500 more cancers did not prevent those other 50 deaths.
Balintfy: There were more than 76,000 men in the PLCO trial that was conducted at ten centers around the United States. Of the men in the trial, roughly 38, 000 were randomly assigned to screening, including annual prostate-specific antigen or PSA tests; the other 38,350 men were randomly assigned to usual care, but received no recommendations for or against annual prostate cancer screening. Dr. Berg explains that the difference between the numbers of deaths in the two groups was not statistically significant. Thus there was no detectable mortality benefit for screening vs. usual-care.
Berg: And so when a man who is deciding whether to be screened or not needs to put this whole picture together, he needs to weigh his own individualized risk, based on his age and family history and race—African-American men tend to be at a somewhat higher risk—and he needs to look at his other health conditions and he needs to talk with his physician or his urologist.
Balintfy: NCI does not have a recommendation about prostate cancer screening. The U.S. Preventive Services Task Force, whose recommendations are considered the gold standard for clinical preventive services, recently concluded that there is insufficient evidence to assess the balance of benefits and harms of prostate cancer screening in men younger than age 75 and recommended against prostate cancer screening in men age 75 and older. But, Dr. Berg emphasizes that information from the PLCO trial will help.
Berg: This is leading towards our holy grail of individualized medicine. However, it comes with uncertainty in the process of us getting that information. It's a very complex mixture before we can say, "All right, you, gentleman sitting in my office today, this is what you're chances are in the future." And then it's still going to be measures of risks and benefits and individual risk tolerance.
Balintfy: Dr. Berg adds that the NCI wants to understand why some prostate cancers are lethal even when found early by annual screening, and what approaches can be used to identify these more aggressive cancers when they can be effectively treated. For more information on this study and cancer research, visit www.cancer.gov.
Stay tuned for an interview about a common condition with no symptoms: pre-diabetes.
(BREAK FOR PUBLIC SERVICE ANNOUNCEMENT)
Pre-Diabetes & Preventing Type 2 Diabetes
Balintfy: Welcome back. We're talking now with Dr. Judith Fradkin; she is the Director of the Division of Diabetes, Endocrinology and Metabolic Diseases at the National Institute of Diabetes and Digestive and Kidney Diseases. She's also a leader of the National Diabetes Education Program, a joint program of the NIH and CDC. We started our discussion with the question, what exactly is pre-diabetes and how many Americans are affected by it?
Fradkin: Pre-diabetes is a condition that is between normal glucose tolerance and diabetes, so the blood sugar levels are higher than normal, but not quite as high as it takes for a diagnosis of diabetes. About 57 million Americans have it, and the reason that it's so important is that people with pre-diabetes are at increased risk of progressing on to type two diabetes and also are at increased risk for cardiovascular disease.
Balintfy: You mentioned glucose tolerance. What is that? How is that a key to knowing what diabetes is?
Fradkin: So pre-diabetes can be established either on the basis of a fasting blood sugar or on the basis of a glucose challenge test where you drink a sugary solution and then check your blood sugar two hours later. The two hour glucose tolerance test is more sensitive and will pick up more people with pre-diabetes, but the fasting blood glucose test is a much easier test, and so most people now are diagnosed with that test. But the important thing to remember about pre-diabetes is that there really are no symptoms of pre-diabetes, so for people who are at risk for type two diabetes, it's really important to get tested. And it's the same test that can determine whether you have pre-diabetes or diabetes.
Balintfy: Okay, so what are some of those risk factors for developing pre-diabetes and perhaps type two diabetes?
Fradkin: The two biggest risk factors are probably a family history of type two diabetes and being overweight or obese. In addition to being overweight and obese and having a family history, other things that put people at risk are having a history or high blood pressure, having abnormal lipid levels, having had diabetes during pregnancy or having delivered a baby who weighs more than 10 pounds, not getting enough physical activity. Some women who have polycystic ovary disease are at increased risk, and there are some signs of insulin resistance, which in a severe case, insulin resistance can show up on the skin, and that can be sort of dark patches on the elbows and behind the neck.
Balintfy: Are there certain demographics that are more at risk for diabetes than others?
Fradkin: Yes, so African-Americans, Hispanic-Americans are at about twice the risk of Caucasian-Americans. Native Americans, American Indians, are at the very highest risk, and Asian-Americans tend to be more at risk even at lower body mass index.
Balintfy: What are some of the keys maybe then to preventing or delaying the onset of pre-diabetes or type two diabetes?
Fradkin: So here we have some really good news. We did a large, multicenter clinical trial across the United States that involved people of all ages and all racial and ethnic groups, and what we found was that you don't have to get down to your ideal body weight to dramatically reduce your risk of moving from pre-diabetes to diabetes. Even losing an average of 15 pounds makes a huge difference in the risk of developing type two diabetes. Rates were decreased by 58 percent over the three-year follow-up period.
Balintfy: What else can you share about the importance of exercise?
Fradkin: So in the diabetes prevention program, the large clinical trial that we did that proved that type two diabetes can be so dramatically reduced, most of the people increased their physical activity simply by briskly walking for 30 minutes a day. And that makes a very, very big difference, particularly for diabetes, because not only does physical activity help you lose weight, but muscle is actually the place that most of the glucose in the body is taken up. And so by actually moving your muscles and contracting your muscles, you're making the muscles more sensitive to insulin and you're making the insulin in your body able to work better. Even for people who have diabetes, often taking a walk after you eat can help reduce the spikes in your blood sugar after a meal. So physical activity is very important.
Balintfy: Terrific. Are there some resources where people can learn more about preventing or delaying the onset of type two diabetes?
Fradkin: Yes, our National Diabetes Education Program, which is a joint effort of the National Institutes of Health and the Center for Disease Control, was created to bring information about NIH-funded clinical trials to the American public, and so all the materials from this diabetes prevention program are available at the National Diabetes Education Program website.
Balintfy: Perfect, and that website is yourdiabetesinfo.org, right?
Balintfy: All right, and the toll free number is 888-693-NDEP.
Fradkin: Yes, thank you very much.
Balintfy: Thank you, Dr. Judith Fradkin. Again the website is www.YourDiabetesInfo.org and the toll free number is 1-888-693-NDEP. And that's it for this episode of the NIH Research Radio podcast. Please join us again on Friday, May 29th when our next edition will be available for download. I'm your host, Joe Balintfy. Thanks for listening.
NIH Research Radio is a presentation of the NIH Radio News Service, part of the News Media Branch, Office of Communications and Public Liaison in the Office of the Director at the National Institutes of Health in Bethesda, Maryland, an agency of the US Department of Health and Human Services.