More Evidence Links BPA to Childhood Obesity

Study finds preteen girls who had high levels of common chemical were twice as likely to be overweight

By Brenda Goodman

HealthDay Reporter

WEDNESDAY, June 12 (HealthDay News) -- There's fresh evidence that the chemical bisphenol A, or BPA, may play a part in childhood obesity.

BPA is a chemical that is widely used in food packaging. Government studies have shown that 92 percent of Americans have detectable levels of BPA in their bodies.

There's intense scientific interest in BPA because it is chemically similar to the hormone estrogen, and there's some concern that it may mimic estrogen's effects in the body, causing harm to the brain and reproductive organs, particularly in children.

Last year, the U.S. Food and Drug Administration formally banned BPA from baby bottles and sippy cups, though manufacturers had already stopped using it. The agency declined to ban it from other food containers, pending further research.

In a new study published online June 12 in the journal PLoS One, researchers measured BPA levels in the urine of more than 1,300 children in China and compared those levels to their body weights.

The study authors also asked the kids about other things that may influence body weight, such as how often they ate junk food, fruits and vegetables, how much exercise they got, whether their parents were overweight and how long they played video games, on average, each day.

After taking all those factors into account, the investigators found that girls aged 9 to 12 who had higher-than-average levels of BPA in their urine were about twice as likely to be obese as those with lower-than-average levels. The researchers didn't see the same association for boys or for older girls.

One explanation for the results may be that girls who are entering puberty are uniquely vulnerable to the effects of hormone-disrupting chemicals, said study author Dr. De-Kun Li, an epidemiologist at Kaiser Foundation Research Institute and the Stanford School of Medicine, in California.

"Human studies are starting to confirm animal studies that show BPA can disrupt energy storage and energy metabolism," said Li.

One of the most recent questions raised about BPA is whether or not it may be an obesogen, or a chemical that contributes to the development of obesity.

In laboratory studies, BPA produces many of the molecular hallmarks of obesity. It makes fat cells bigger, it blocks the function of a protein called adiponectin, which protects against heart disease, and it disrupts the balance of testosterone and estrogen -- hormones that are important for maintaining a healthy body mass.

One expert found the study results troubling.

"Clearly, unhealthy diet and physical activity are still the leading causes of the childhood obesity epidemic worldwide, but this study adds further concern to the notion that environmental chemicals may be independent contributors," said Dr. Leonardo Trasande, an associate professor of pediatrics, environmental medicine and health policy at NYU Langone Medical Center, in New York City.

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More Evidence Shows Hormone Therapy May Increase Breast Cancer Risk

In new analysis, researchers found risk highest when used just before menopause

By Kathleen Doheny

HealthDay Reporter

FRIDAY, March 29 (HealthDay News) -- Women who take hormone therapy that includes estrogen and progestin are at increased risk of developing breast cancer and dying from it, especially if they start taking the therapy just as menopause begins, a new analysis confirms.

Researchers followed nearly 42,000 women, all of whom were past menopause, for an average of more than 11 years. Of those, more than 25,000 did not use hormone therapy and more than 16,000 took estrogen and progestin, also called combined hormone therapy. For this analysis, the researchers did not include estrogen-only therapy, used by women who have had a hysterectomy.

At the end of the follow-up period, more than 2,200 of the women were found to have breast cancer. Compared to non-users, those who took combined therapy were more likely to have breast cancer, said Dr. Rowan Chlebowski, a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center. Chlebowski led the study, which was published in the March 29 issue of the Journal of the National Cancer Institute.

The link has been found in other studies, but Chlebowski also found the risk was greatest among those who took the hormones closest to menopause. "Women starting within months of menopause had about a threefold greater risk than women starting 10 years after menopause," Chlebowski said.

For the new analysis, Chlebowksi looked at results from the Women's Health Initiative observational study. He compared the findings with those from the Women's Health Initiative randomized clinical trial, in which women were assigned to different treatments.

The Women's Health Initiative included four clinical trials and an observational study. Women were all past menopause and were aged 50 to 79.

Chlebowski said he did the new analysis to resolve what he saw as unanswered questions. In the trial, only about one-third, or 5,000, of the women were in their 50s when they started the study. As that is the typical age for menopause to start, about two-thirds of the women in the trial were in their 60s or beyond, so began to take hormones several years after menopause.

Chlebowski set out to see if the link between breast cancer risk and combined hormone therapy use was influenced by earlier use of hormones.

"We had a substantial number closer to menopause than the clinical trial of [the Women's Health Initiative]," he said.

He found, however, that not only was the risk of breast cancer still increased, but it also increased even more if the women were closer to menopause when they began to take the hormones.

He speculated that women who start the hormone therapy close to menopause still have circulating levels of estrogen high enough to make them exceed some threshold, beyond which it may become hazardous.

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New Analysis Says Evidence Lacking for HRT-Breast Cancer Link

Researchers took fresh look at three large studies, concluded data wasn't convincing

By Kathleen Doheny

HealthDay Reporter

THURSDAY, March 14 ( HealthDay News) -- Although several large studies in recent years have linked the use of hormone therapy after menopause with an increased risk of breast cancer, the authors of a new analysis claim the evidence is too limited to confirm the connection.

Dr. Samuel Shapiro, of the University of Cape Town Medical School in South Africa, and his colleagues took another look at three large studies that investigated hormone therapy and its possible health risks -- the Collaborative Reanalysis, the Women's Health Initiative (WHI) and the Million Women Study.

Together, the results of these studies found overall an increased risk of breast cancer among women who used the combination form of hormone therapy with both estrogen and progesterone. Women who have had a hysterectomy and use estrogen-only therapy also have an increased risk, two of the studies found. The WHI, however, found that estrogen-only therapy may not increase breast cancer risk and may actually decrease it, although that has not been confirmed in other research.

After the WHI study was published in July 2002, women dropped hormone therapy in droves. Many experts pointed to that decline in hormone therapy use as the reason breast cancer rates were declining.

Not so, Shapiro said: "The decline in breast cancer incidence started three years before the fall in HRT use commenced, lasted for only one year after the HRT drop commenced, and then stopped."

For instance, he said, between 2002 and 2003, when large numbers of women were still using hormone therapy, the number of new breast cancer cases fell by nearly 7 percent.

In taking a look at the three studies again, Shapiro and his team reviewed whether the evidence satisfied criteria important to researchers, such as the strength of an association, taking into account other factors that could influence risk. Their conclusion: The evidence is not strong enough to say definitively that hormone therapy causes breast cancer.

The study is published in the current issue of the Journal of Family Planning and Reproductive Health Care.

The new conclusion drew mixed reactions from experts.

In an editorial accompanying the study, Nick Panay, a consultant gynecologist at the Queen Charlotte's & Chelsea Hospital in London, supported the conclusions of the new analysis. "If there is a risk, the risk is small, and the benefits of HRT can be life-altering," he wrote. "It is vital that we keep this in perspective when counseling our patients."

The hormone therapy in use today, Panay said, is lower in dose than those used in the previous research. "In principle, we tend to start with lower doses than we used to and increase as required until full symptom relief has been achieved," he said.

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Sugar and Excess Weight: Evidence Mounts

Jan. 15, 2013 -- Eating less sugar is linked with weight loss, and eating more is linked with weight gain, according to a new review of published studies.

The review lends support to the idea that advising people to limit the sugar in their diets may help lessen excess weight and obesity, the New Zealand researchers conclude.

"The really interesting finding is that increasing and decreasing sugar had virtually identical results [on weight], in the opposite direction of course," says researcher Jim Mann, DM, PhD, professor of human nutrition and medicine at the University of Otago.

Mann and his team analyzed the results of 30 clinical trials and 38 other studies. Their goal was to summarize the evidence on the link between dietary sugars and body weight in adults and children.

For years, some experts have linked excess sugar in the diet, including both sugary foods and drinks, to obesity and a higher risk of chronic disease, including heart disease and diabetes.

However, those studies have produced conflicting findings.

The new review is published in BMJ.

Since 2003, the World Health Organization (WHO) has recommended that intake of "free" sugars be limited to 10% of calories daily. The WHO is in the process of updating that recommendation, and it commissioned the review of this research to help that process.

Free sugars are defined as sugars added to foods by the manufacturer, cook, or consumer, or those naturally present in fruit juice, syrups, and honey.

In some of the studies evaluated, adults were told to lower their sugar intake.

Those who did lowered their weight slightly, Mann says. Over the course of the studies, which lasted for up to eight months, the average weight loss was about 1.7 pounds.

Adults who increased their sugar intake over the same average time period increased their weight nearly the same amount.

Over time, Mann says, that decrease (and increase) could be more. "There is also evidence that the longer the study, the more striking the effect," he says.

The link between sugar intake and weight was less consistent in studies of children, Mann found. He says that is manly due to the kids not following the diet advice.

When they looked only at sugary beverages, however, the link between a sugary beverage habit and being overweight in children was strong.

Those who had the highest intake after a year were about 1.5 times as likely to be overweight or obese as those with the lowest intake, Mann found.

The Sugar Association declined to comment on the study, but says the news release "is a classic example of misrepresented science."

But the American Beverage Association issued this statement: "This study confirms that it's calories that count when it comes to weight loss, not uniquely calories from sugar. As the authors noted, when calories from sugar were replaced with calories from carbohydrates, there was no change in weight. This would not have been the case if sugars had a unique effect on body weight."

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