Your Health

Cutting down on carbs may help people lose weight, but it may not be so good for lowering cholesterol, new research shows.

People who ate a diet low in carbohydrates but relatively high in fat lost the same amount of weight over six weeks as those who consumed a high-carb diet.

But levels of low-density lipoprotein (LDL) or “bad” cholesterol increased significantly in the low-carb group, while they fell in the high-carb group. High LDL levels are a risk factor for heart disease because they are linked to clogged arteries.

Low-carb diets have become increasingly popular in recent years, and proponents claim they may be more effective for reducing diabetes risk and cholesterol levels, Dr. Teri L. Hernandez of the University of Colorado at Denver in Aurora and her colleagues write in their report in the American Journal of Clinical Nutrition.

But little is actually known about how these diets compare with higher-carb weight loss plans in terms of these effects, they add.

To investigate the effects of diet on these measures during active weight loss, Hernandez and her team randomly assigned 32 obese adults to follow a low-carbohydrate diet, including 20 grams of carbohydrate or less daily, or a high-carb diet with 55 percent of calories coming from carbohydrates for six weeks.

Both groups lost around 6 kilograms (13 pounds). But the individuals on the low-carb diet actually had an average increase of 12 milligrams per deciliter increase in their LDL levels, up from 109 milligrams per deciliter (less than 100 is considered optimal); the high-carb diet group showed a 7 milligram per deciliter decrease, down from 102.

The low-carb group also showed greater increases in their levels of free fatty acids, which are released into the blood when the body breaks down stored fat. High levels of free fatty acids make it more difficult for the liver to store glucose, which in turn ups sugar levels in the blood. Consistently high sugar levels define diabetes.

“These data suggest that a high-fat diet may have adverse metabolic effects during active weight loss,” Hernandez and her team conclude.

SOURCE: American Journal of Clinical Nutrition.

Naps play an important role in infant learning by helping children’s developing brains retain information, a new study has found.

Researchers at the University of Arizona in Tucson found that infants who have daytime naps are more likely to exhibit an advanced level of learning called abstraction — the ability to detect a general pattern contained in new information.

In this study of 48 infants, phrases from an artificial language were repeatedly played to the 15-month-olds until they became familiar with them. Follow-up tests showed that infants who slept within four to eight hours after hearing the phrases showed evidence of abstract learning. This wasn’t the case for infants who didn’t have a nap within that timeframe.

“What we know is that infants have mostly REM sleep, given the type of sleep they have, given how their brains are developed at that point. And they have to get some of that sleep within a reasonable amount of time after inputting information in order to be able to do abstracting work on it. If they don’t sleep within four to eight hours, they probably just lose the entire thing,” lead researcher Lynn Nadel, a professor in the psychology department, said in a university news release.

The findings were presented Feb. 21 at the American Association for the Advancement of Science annual meeting, in San Diego.

While it’s important to provide infants and young children with the kind of mental stimulation that comes from talking and reading to them, it’s also crucial to ensure this is done as part of a well-regulated daily cycle that includes adequate sleep, Nadel said.

SOURCE: University of Arizona, news release.

Just in case the world needed more evidence on the matter, along come four new studies verifying that exercise is indeed good for you, even critical if you plan to survive to a vigorous, hardy and tough-boned old age.

All four studies appear in the Jan. 25 issue of the Archives of Internal Medicine.

“I like to see this laid out, but every bit of information [already] suggests that being active is the healthier way and being inactive is the abnormal, unhealthy way,” said James O. Hill, professor of pediatrics and director of the Center for Human Nutrition at the University of Colorado at Denver. “Exercise is better than any drug or anything else we have for aging. There’s no downside. If this were a drug, it would be the safest, most effective drug in the universe.”

The first study, based on data from the Nurses’ Health Study in the United States, found that women who were more physically active during middle age were more likely to be “successful survivors” by the time they reach 70.

Even walking and other moderate-intensity exercises lowered the risk for chronic diseases, heart trouble and cognitive impairment, the study found. That’s good news for women intimidated by activities such as tennis or running.

“In terms of magnitude, walking and other moderate activities were almost equivalent to the benefit gained from more vigorous physical activity,” said study lead author Dr. Qi Sun, a research fellow at the Harvard School of Public Health in Boston, adding that this finding was somewhat surprising.

The second study, also focusing on women, found that those who participated in a higher intensity exercise program four days a week had stronger bones and less chance of falling than women who were in a “well-being” program that included relaxation, along with flexibility, endurance and balance.

The ramped-up exercise program did not, however, reduce the risk of heart disease, said the German researchers.

Another study out of Germany found more evidence that exercise — either moderate or high-intensity — reduced the risk of cognitive impairment in men and women over the age of 55 over a two-year follow-up period.

And, finally, researchers in British Columbia, Canada, reported that women who practiced resistance training either once or twice a week had improved cognitive skills, but only in the areas of attention and conflict resolution, compared to women who focused on balance and toning activities.

The resistance training, which included leg presses on a resistance machine, had the added benefit of strengthening the quadriceps.

Surprisingly, women performing resistance training also experienced reductions in brain volume, a phenomenon normally linked with poorer cognitive function. This paradox needs more study, the study authors said.

An accompanying commentary in the journal pointed out that pretty much all physical ailments in later life result at least partly from lack of physical activity.

Meanwhile, exercise has been shown to improve arthritis, osteoporosis, heart disease, lung disease, cancer and many more woes.

“The bottom line,” said Sun, “is that, no matter what, if you can you should do some physical activity.”

SOURCES: Qi Sun, M.D., Sc.D., research associate, Harvard School of Public Health, Boston; James O. Hill, Ph.D., professor, pediatrics, and director, Center for Human Nutrition, University of Colorado at Denver

A new report says that male partners of teenage girls and young women who engage in physical and sexual violence also often try to sabotage the birth control the women are using.

The study, which appears online in the January issue of Contraception, also finds that women who experience both birth-control sabotage and violence from their partner are twice as likely to have an unintended pregnancy.

“This study highlights an under-recognized phenomenon where male partners actively attempt to promote pregnancy against the will of their female partners,” study author Elizabeth Miller, an assistant professor of pediatrics in the University of California at Davis School of Medicine, said in a news release from the school. “Not only is reproductive coercion associated with violence from male partners, but when women report experiencing both reproductive coercion and partner violence, the risk for unintended pregnancy increases significantly.”

The study was conducted from 2008-2009 at five health clinics that deal with reproductive issues in Northern California. About 1,300 women aged 16 to 29 took part by responding to a computerized survey.

About 15 percent said they’d experienced birth-control sabotage, and more than half reported physical or sexual violence from a partner. More than one-third of those who said they had been the victim of partner violence also acknowledged experiencing either pregnancy coercion or birth-control sabotage, the researchers found.

“We have known about the association between partner violence and unintended pregnancy for many years,” study senior author Jay Silverman, an associate professor of society, human development and health in the Harvard School of Public Health, said in the news release. “What this study shows is that reproductive coercion likely explains why unintended pregnancies are far more common among abused women and teens.”

SOURCE: University of California at Davis

This is the first randomized phase 3 trial (the final and most comprehensive aspect of a three-phase clinical trials process) to demonstrate a clinical benefit of lenalidomide following transplant for multiple myeloma. However, the trial has not yet shown evidence of an overall survival benefit.

The types of side effects observed in this trial were similar to those observed in other clinical trials with lenalidomide. Detailed results from this trial will be presented at a future scientific meeting.

“This study answers the important question for multiple myeloma patients regarding maintenance lenalidomide therapy starting at 100 days following transplant,” said Philip L. McCarthy, Jr., M.D., associate professor of medicine at Roswell Park Cancer Institute and principal investigator of this study. “We now know that prolonged maintenance therapy with lenalidomide when compared to placebo will delay disease progression. This is an exciting advance in the field of multiple myeloma therapy and occurred due to the willingness of multiple myeloma patients to participate in this study and to the cooperation of the many physicians and study groups involved.”

Lenalidomide, a derivative of thalidomide, was approved by the U.S. Food and Drug Administration in 2006 to be used in combination with dexamethasone, a steroid, for the treatment of multiple myeloma in patients who received at least one prior therapy for their disease. Celgene Corporation, Summit, N.J., provided lenalidomide for this trial under a clinical trials agreement with NCI.

“This trial is a prime example of an important study question that was effectively carried out by collaboration between NCI-sponsored oncology cooperative groups, NCI, and NHLBI co-sponsored Blood and Marrow Clinical Trials Network with support from Celgene Corp., the discoverer, developer, and manufacturer of lenalidomide. This collaboration made it possible to rapidly complete accrual to the trial and to provide information in a timely manner that informs an important change in medical practice,” said Richard F. Little, M.D., head, Blood and AIDS Cancers Therapeutics Section of NCI’s Cancer Therapy Evaluation Program, part of the Division of Cancer Treatment and Diagnosis.

Multiple myeloma occurs when a type of immune cell, called a plasma cell, becomes too numerous and crowds out healthy blood cells in the bone marrow (the spongy tissue inside the bones), causing pain, and gradually damaging the bones and other body organs. An estimated 20,580 people will be diagnosed with multiple myeloma in the United States in 2009. Approximately 46,000 people are living with the disease in the United States.

CALGB 100104/ECOG 100104: A Phase III Randomized, Double-Blind Study of Maintenance Therapy With CC-5013 Or Placebo Following Autologous Stem Cell Transplantation For Multiple Myeloma. An overview of the design and entry criteria for this trial can be found at http://www.Cancer.Gov/Clinicaltrials/Calgb-100104 (Clinical Trial Registry number NCT00114101).

Initial results from a large, randomized clinical trial for patients with multiple myeloma, a cancer of the blood and bone marrow, showed that patients who received the oral drug lenalidomide (Revlimid, also known as CC-5013) following a blood stem cell transplant had their cancer kept in check longer than patients who received a placebo. The clinical trial, for patients ages 18 to 70, was sponsored by the National Cancer Institute (NCI), and conducted by a network of researchers led by the Cancer and Leukemia Group B (CALGB) in collaboration with the Eastern Cooperative Oncology Group (ECOG) and the Blood and Marrow Transplant Clinical Trials Network (BMT CTN). The BMT CTN is co-sponsored by NCI and the National Heart, Lung, and Blood Institute, both parts of the National Institutes of Health.

The independent data and safety monitoring committee overseeing the trial (known as CALGB-100104) found that the study demonstrated a longer time before the cancer progressed following autologous blood stem cell transplantation for those patients on the study drug than those on placebo and so the trial was stopped early. Autologous blood stem cell transplantation is a procedure in which a patient’s own blood stem cells are removed, the patient is then treated with high doses of chemotherapy and/or radiation therapy to kill the cancer, after which the blood stem cells are returned to the patient. It is a common procedure for patients with multiple myeloma.

A total of 568 patients with multiple myeloma, who had received no more than 12 months of prior therapy and no prior transplant, were enrolled between December 2004 and July 2009. All patients received autologous transplantation following a high dose of a drug called melphalan, which is commonly used to treat multiple myeloma. Ultimately, 460 patients who had adequate organ function and no evidence of progressive disease, were randomized between 90 and 100 days after transplant to receive lenalidomide or placebo. Patients began lenalidomide or placebo between day 100 to 110 and continued until they had evidence of progressive disease.

Among the patients who received placebo, half had their myeloma progress (worsen) within an estimated 778 days. In contrast, for those patients taking lenalidomide, a median time to progression cannot be defined because fewer than half the patients had worsening of their myeloma. This represents a 58 percent reduction in the risk of disease progression for the group taking lenalidomide. This difference in time to progression was highly statistically significant.

The brains of autistic people are less active than expected when they’re engaged in self-reflective thought, a finding that helps explain autism-related social difficulties, say British researchers.

Using functional MRI, they measured the brain activity of 66 males, half of whom had autism, while they were asked questions about their own or the Queen’s thoughts, opinions,preferences, or physical characteristics.

The researchers were particularly interested in an area of the brain called the ventromedial prefrontal cortex, which is known to be active when people think about themselves.

In non-autistic volunteers, this part of the brain was more active when they were asked questions about themselves than when they were thinking about the Queen. But the response was equal when those with autism were asked about themselves and the Queen.

“This new study shows that within the autistic brain, regions that typically prefer self-relevant information make no distinction between thinking about the self or another person. This is strong evidence that in the autistic brain, processing itself is atypical,” said Michael Lombardo of the Autism Research Centre at the University of Cambridge.

“Navigating social interactions with others requires keeping track of the relationship between oneself and others,” he explained. “In some social situations it is important to notice that ‘I am similar to you,’ while in other situations it might be important to notice that ‘I am different to you.’ The atypical way the autistic brain treats self-relevant information as equivalent to information about others could derail a child’s social development, particularly in understanding how they relate to the social world around them.”

Yet previous research has suggested there may be racial variations in what constitutes a healthy BMI. Diabetes risk for Asians start to rise at a BMI of about 23, for example. An optimal BMI for blacks may also vary somewhat, Katzmarzyk said.

“BMI may mean different things for different people,” he said. “The study suggests we may need to think about ethnic-specific thresholds to identify obesity-related health risks.”

Eric Bailey, a professor of anthropology and public health at East Carolina University and author of Food Choice and Obesity in Black America: Creating a New Cultural Diet, said BMI recommendations were developed using too little data on black Americans or other racial and ethnic groups.

“We are using BMI as a ‘gold standard,’ but it needs to be reassessed,” Bailey said. “It does not necessarily apply to each and every population in the same way. Our biology and genetic makeup is slightly different. African-Americans may be healthier at a different BMI compared to a European population.”

Biology aside, Bailey added, there is no question that obesity remains a serious issue in the black community. Poverty can make affording fresh fruits and vegetables and the healthiest cuts of meat more difficult, while unsafe neighborhoods discourages getting adequate exercise.

“Many times, sociological, behavioral and cultural issues overrides the biological,” Bailey said. “One-third of African Americans are still in poverty, and that influences the types of foods you are able to eat.”

In another study from the same issue, researchers found that gene variants that have been implicated in a tendency toward obesity played only a small role in a person’s BMI.

Previous research in twins has suggested as much as 40 percent to 85 percent of obesity can be blamed on the genes, but the new research shows the influence of genetic variants may be much smaller.

Researchers at the University of Cambridge looked for 12 genetic markers for obesity in more than 20,000 participants from the United Kingdom. Those with at least one gene marker were 3 percent to 14 percent more likely to be obese than those without the marker, while each additional genetic marker raised the risk of obesity by nearly 11 percent.

But taken together, the genetic variations accounted for only about a one percent variation in BMI — meaning the currently known markers are poor predictors of who is at risk for obesity, according to the study.

Researchers said it’s possible that other, more important obesity-related gene variants have yet to be identified.

Blacks tend to carry around less of a particularly unhealthy type of abdominal fat than whites, even though they suffer more from obesity-linked illness, researchers report.

The new finding suggests that body-mass index (BMI) guidelines may need to be tailored to specific racial groups to better reflect risk, experts say.

“The study clearly shows we have these racial differences in body fat, not just in the type of body fat but where the fat is stored, and these are important differences,” said study author Peter Katzmarzyk, a professor of population science at Pennington Biomedical Research Center in Baton Rouge, La.

Adipose (fat) tissue is found throughout the body. Subcutaneous adipose tissue is found just under the skin, while visceral adipose tissue is found in the abdominal cavity around the organs.

Fat settling around the organs has been linked to development of obesity-related diseases such as cardiovascular disease and type 2 diabetes, according to background information in the article.

But you can’t tell just by looking at someone how much visceral fat someone has. Even a pot belly won’t tell you for sure because visceral fat is deep within the body cavity, Katzmarzyk said.

In the study, researchers used computer tomography (CT scans) and dual- energy X-ray absorptiometry (DXA) to measure visceral fat in about 1,400 white men and women and 570 black men and women aged 18 to 84. Participants’ height, weight, BMI and total body fat composition were also measured.

At a given body fat percentage, black men and women had lower visceral fat than white men and women. Conversely, blacks also tended to have higher subcutaneous fat than whites. Researchers controlled for age and smoking status, among other variables.

The study appears in the January issue of The American Journal of Clinical Nutrition.

Despite the tendency to have less visceral fat, black Americans are still at higher risk of dying from obesity-related diseases such as diabetes and cardiovascular disease. One explanation for this is that blacks have higher overall obesity rates overall, Katzmarzyk said.

About 31 percent of white adults and 45 percent of black adults are obese, according to the study.

“It’s a paradox,” Katzmarzyk said. “The fact that white individuals have more visceral adipose tissue and also have lower rates of obesity-related disease is probably because African-Americans have higher rates of obesity overall.”

The findings also bring up the issue of whether the “one-size-fits-all” BMI guidelines apply equally to all races, Katzmarzyk said.

BMI is a calculation based on height and weight. While a high BMI tends to mean you also have a lot of body fat, BMI is not a direct measurement of fat composition. A very muscular person, for example, may have a high BMI but low body fat composition.

A BMI of 30 or above is considered obese, while a BMI of 25 or above is overweight.

The number of baby boys conceived by a fertility treatment known as ICSI may be lower than what is produced by Mother Nature, a new study suggests.

On average, there are 105 baby boys born for every 100 girls — a natural advantage that helps balance out the higher number of deaths among male fetuses and infants. But in the new study, researchers found that this male-to-female birth ratio seems to be reversed when infants are conceived through intracytoplasmic sperm injection, or ICSI.

Among more than 15,000 U.S. babies born in 2005 via assisted reproduction, the investigators found that a particular ICSI approach appeared to result in a smaller-than-average number of boys.

The effect was seen when ICSI was performed using blastocyst-stage embryos — where embryos are allowed to mature a couple days longer than the traditional norm before they are transferred to the mother. This allows doctors to transfer fewer embryos, reducing the odds of couples having triplets or higher-order births.

Among couples undergoing this procedure, just under 50 percent of births were boys. That compared with a U.S. norm of 52.5 percent for 2005, according to findings published in the journal Fertility & Sterility.

ICSI involves injecting sperm from the father directly into eggs taken from the mother; if one or more embryos develop over the next few days, they are transferred to the mother’s uterus.

ICSI is typically used to treat male fertility problems, such as a low sperm count or poor-quality sperm. However, it is also sometimes used when the cause of a couple’s infertility is unclear, and some fertility clinics opt to use ICSI for all patients.

The full implications of the current findings are not clear, according to the researchers, led by Dr. Barbara Luke of Michigan State University in East Lansing.

About 1 percent of U.S. births result from all assisted reproductive techniques combined, meaning ICSI accounts for only a small number of births. So it is unlikely that the small effects on male-to-female birth ratio seen in this study would have “any major implications for public health,” Luke and her colleagues write.

Still, they conclude, “because our findings suggest that ICSI may reduce the sex ratio, we recommend that ICSI only be done if medically necessary, in an effort to prevent this potential side effect.”

It is not clear why ICSI might reduce the proportion of male births. However, Luke and her colleagues point out, the study found no evidence that male infertility itself was related to a lower sex ratio — supporting the idea that something about the ICSI process is to blame.