Thursday, August 28, 2008

Study suggests low-level arsenic exposure may be linked with Type 2 diabetes

Some reasonable caution in this report. Just a small personal note: As a result of past medical "wisdom", I am full of arsenic and yet I test out fine on diabetes tests.

A new analysis of government data is the first to link low-level arsenic exposure, possibly from drinking water, with Type 2 diabetes, researchers say. The study's limitations make more research necessary. And public water systems were on their way to meeting tougher U.S. arsenic standards as the data were collected. Still, the analysis of 788 adults' medical tests found a nearly fourfold increase in the risk of diabetes in people with low arsenic concentrations in their urine compared to people with even lower levels.

Previous research outside the United States has linked high levels of arsenic in drinking water with diabetes. It's the link at low levels that's new. The findings appear in Wednesday's Journal of the American Medical Association. "The good news is, this is preventable," said lead author Dr. Ana Navas-Acien of Johns Hopkins Bloomberg School of Public Health in Baltimore.

New safe drinking water standards may be needed if the findings are duplicated in future studies, Navas-Acien said. She said they've begun a new study of 4,000 people. Arsenic can get into drinking water naturally when minerals dissolve. It is also an industrial pollutant from coal burning and copper smelting. Utilities use filtration systems to get it out of drinking water.

Seafood also contains nontoxic organic arsenic. The researchers adjusted their analysis for signs of seafood intake and found that people with Type 2 diabetes had 26 percent higher inorganic arsenic levels than people without Type 2 diabetes. How arsenic could contribute to diabetes is unknown, but prior studies have found impaired insulin secretion in pancreas cells treated with an arsenic compound.

The policy implications of the new findings are unclear, said Molly Kile, an environmental health research scientist at the Harvard School of Public Health. Kile wrote an accompanying editorial in the journal. "Urinary arsenic reflects exposures from all routes - air, water and food - which makes it difficult to track the actual source of arsenic exposure let alone use the results from this study to establish drinking water standards," Kile said.

Also, the findings raise a chicken-and-egg problem, she said, since it's unknown whether diabetes changes the way people metabolize arsenic. It's possible that people with diabetes excrete more arsenic. The United States lowered arsenic standards for public water systems to 10 parts per billion in 2001 because of known cancer risks. Compliance was required by 2006, years after the study data were collected in 2003 and 2004.


Are You Sure You Want Fries With That?

Mandatory calorie counts cross the line between informing and nagging

In a 2007 survey of California voters, 84 percent said they thought the government should force restaurant chains to display calorie numbers on their menus and menu boards. That may happen soon: The state Assembly is considering a bill, already approved by the state Senate, that would make California the first state to impose such a menu mandate.

Yet the desires that people express in polls are often at odds with the preferences they reveal in the marketplace. The restaurant business is highly competitive. If customers really were clamoring for conspicuous calorie counts, restaurants would provide them voluntarily. A legal requirement is necessary not because consumers want impossible-to-ignore nutritional information but because, by and large, they don't.

Since they overestimate the demand for nutritional information, advocates of menu mandates also overestimate the impact of making it more visible. "Menu board labeling has the potential to dramatically alter the trajectory of the obesity epidemic in California," the California Center for Public Health Advocacy claims, projecting a weight loss of nearly three pounds a year per fast food consumer. The New York City Department of Health and Mental Hygiene, which began enforcing a calorie count requirement last month, predicts it will stop 150,000 people from becoming obese and prevent 30,000 cases of diabetes during the next five years.

Both estimates are based on a study conducted by New York's health department before the city's menu rule took effect. The researchers asked about 7,300 customers at fast food restaurants in the city whether they had seen and made use of nutritional information, which is typically displayed on posters, brochures, tray liners, or counter mats (as well as on the chains' websites). They also examined the customers' receipts so they could calculate the calorie content of the food they purchased.

The only chain where a substantial share of customers said they noticed nutritional information was Subway, where 32 percent reported seeing it, compared to 4 percent at the other chains. Since Subway promotes a subset of its menu as lower in calories and fat than its competitors' offerings, using a pitchman who lost hundreds of pounds while eating at the chain every day, this disparity is not surprising.

But even at Subway, calorie information seemed to make a difference for just one in eight customers. Of those who reported seeing the calorie information at Subway, 37 percent-12 percent of all Subway customers-said it affected their purchases. Subway customers who said they used calorie information bought about 100 fewer calories than those who said they didn't see it and those who said they saw it but didn't use it.

Notably, "there was no significant difference in mean calories purchased by patrons reporting seeing but not using calorie information and patrons who reported not seeing calorie information." In other words, simply making people aware of calorie content is not enough to affect their food choices.

The information's influence may be limited to people who are predisposed to count calories. If so, the impact of menu mandates will depend on the extent to which those people are not taking advantage of less obtrusive nutritional information already provided by restaurants.

The importance of pre-existing preferences also suggests that it's risky to extrapolate from Subway customers (who, given the chain's marketing, are probably especially weight-conscious) to fast food consumers in general. Another unresolved question is whether people compensate for fewer calories consumed at McDonald's or KFC by eating more at home or elsewhere.

Even if menu regulations don't make any difference on balance, Yale obesity researcher Kelly Brownell recently told the Los Angeles Times, "there's still the issue of the consumer's right to know." What about the consumer's right not to know? The same research that supporters of menu mandates like to cite indicates that most consumers prefer to avoid calorie counts, enjoying their food in blissful ignorance. There's a difference between informing people and nagging them.


Wonders of the human immune system: Blood of survivors of 1918 flu still protects against disease

Nearly a century after history's most lethal flu faded away, survivors' bloodstreams still carry super-potent protection against the 1918 virus, demonstrating the remarkable durability of the human immune system. Scientists tested the blood of 32 people aged 92 to 102 who were exposed to the 1918 pandemic flu and found antibodies that still roam the body looking to strangle the old flu strain. Researchers manipulated those antibodies into a vaccine and found that it kept alive all the mice they had injected with the killer flu, according to a study published online Sunday in the journal Nature.

There's no pressing need for a 1918 flu vaccine because the virus has long since mutated out of its deadly form and is extremely unlikely to be a threat anymore, experts said. What's more important in this research, they said, is that it confirms theories that our immune system has a steel-trap memory. "It's incredible. The Lord has blessed us with antibodies our whole lifetime," said study co-author Dr. Eric Altschuler at the University of Medicine and Dentistry in New Jersey. "What doesn't kill you, makes you stronger."

This is the longest that specific disease-fighting cells have lasted in people, said study lead author Dr. James Crowe, a professor of microbiology and immunology at Vanderbilt University Medical Center in Nashville, Tenn. But these antibodies don't just survive; they have mutated tremendously and now bind tighter to disease cells than other antibodies. That makes them more potent, he said.

Crowe said he hopes to use similar techniques to boost the potencies of vaccines that would be more useful now against newer bird flu strains that could become epidemics.

The 1918 flu killed about 50 million people worldwide and nearly everybody else was exposed to the virus, Crowe said. The specific 1918 virus was lost to the world for decades, until it was reconstructed about three years ago using genetic material from victims. When scientists tested the antibodies from survivors on infected mice, they did so in a high level biosecurity lab at the Centers for Disease Control and Prevention in Atlanta.

The idea for the new study came from an old TV show, said Altschuler. In an episode of the since-cancelled TV series "Medical Investigation," a town improbably gets infected with the 1918 flu and the doctors treat everyone with the reluctantly donated blood of an old butler who survived the original pandemic, he said.

That prompted Altschuler, a professor of rehabilitation medicine who doesn't normally study flu, to look into the idea of testing people more than 90 years old for antibodies. The National Institutes of Health, which paid for much of the study, connected Altschuler with experts in the field and he found the elderly antibody donors.

The findings make sense, said Dr. Anthony Fauci, director of the National Institute for Allergies and Infectious Diseases in Bethesda, Md., who wasn't involved with the study. Recent studies have estimated that the human immune system should last many decades, but this gives real proof, he said. "This is the mother of all immunological memory here," Fauci said.


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