Sunday, March 29, 2009

Student Obesity Linked to Proximity to Fast-Food Outlets

A 5% increased incidence is very weak. The Federal Reference Manual on Scientific Evidence, Second Edition says (p. 384): "the threshold for concluding that an agent was more likely than not the cause of an individual's disease is a relative risk greater than 2.0." So the 5% in the present study stacks up badly when compared with 200%.

If there is any real meaning in the findings, they probably show that fast food outlets tend to locate more in areas where their customers are clustered -- in poorer areas. And poorer people tend to be fatter anyway

Teens who attend classes within one-tenth of a mile of a fast-food outlet are more likely to be obese than peers whose campuses are located farther from the lure of quarter-pound burgers, fries and shakes. Those are the findings of a recent study by researchers from UC Berkeley and Columbia University seeking a link between obesity and the easy availability of fast food. The academics studied body-fat data from more than 1 million California ninth-graders over an eight-year period, focusing on the proximity of the school to well-known chains including McDonald's, Burger King, KFC, Taco Bell and Pizza Hut. Their conclusion: Fast food and young waistlines make lousy neighbors, the LA Times reports.

The presence of an outlet within easy walking distance of a high school — about 530 feet or less — resulted in a 5.2% increase in the incidence of student obesity compared with the average for California youths, a correlation deemed "sizable" according to the findings. The link vanished when these fast-food joints were located farther from campus, presumably because students couldn't easily reach them. Nor was it present in schools located near full-service eateries, whose prices and service times don't typically match student budgets, tastes or schedules, reports Times writer Jerry Hirsch.

"Fast food offers the most calories per price compared to other restaurants, and that's combined with a high temptation factor for students," said Stefano DellaVigna, a UC Berkeley economist and one of the paper's authors, the Times reports. The researchers said cities concerned about battling teen obesity should consider banning fast-food restaurants near schools.

The findings are likely to fuel the debate over what's driving America's obesity epidemic. Concerned about growing rates of diabetes and heart disease — particularly among young people — state and local governments nationwide are taking aim at fatty, high-calorie foods.

California has been one of the most aggressive. Students can no longer purchase soda or junk food in Golden State schools. Some districts won't allow bake sales. California has banned artery-clogging trans fats, and Los Angeles has a one-year moratorium on new fast-food outlets in a 32-square-mile area of South L.A.

More than a dozen states and numerous cities are pondering legislation patterned after a new California law forcing chain restaurants to list calorie counts on their menus.

But blaming restaurants for the nation's weight problem strikes many as misguided. Obesity can be a product of a variety of factors, experts say, including genetics, lack of exercise and household nutrition. Courts have struck down patrons' attempts to sue restaurant chains for making them fat.

Not every group living or working in areas where fast food is plentiful experiences a higher incidence of obesity. The report's authors studied weight data for pregnant women, another group for which statistics are easily available. They found a much smaller correlation between the expectant mothers' weight gain and their proximity to the same type of burger, chicken and pizza restaurants.

The high schoolers studied appeared more susceptible to the temptations of fast food. "School kids are a captive audience. They can't go very far from school during lunch, but adults can get in their car and have more choices," said Janet Currie of Columbia University, a co-author, the Times reports.


Very hot tea and coffee linked to raised oesophagus cancer

This seems entirely reasonable. Note that, unlike most epidemiological studies, the effect found was large: An 800% rise versus the 30% that seems to be the average for the studies I see

You may be gasping for that freshly brewed cup of tea or coffee, but waiting five minutes before drinking it could save your life. Researchers have found that a taste for very hot drinks may be linked to cancer of the oesophagus and that the risk of contracting the disease may increase eightfold as a result of drinking tea hotter than 70C (158F).

The oesophagus is the tube that carries food from the throat to the stomach and such cancers kill more than half a million people around the world every year.

In Europe and America it is usually caused by smoking or alcohol, but a study published in the British Medical Journal found that there was a particularly high incidence of the disease in northern Iran, where smoking and alcohol consumption is low. The people of Golestan province do, however, drink large amounts of very hot tea - at least 70C.

Researchers studied the tea-drinking habits of 300 people with the cancer and a group of 571 healthy people from the same area. Compared with drinking warm or lukewarm tea (65C or less), drinking it at 65-69C doubled the risk of oesophageal cancer, while drinking it at 70C or more was associated with an eightfold increased risk.

Drinking tea less than two minutes after pouring, rather than waiting four or five minutes, led to a fivefold increase in the risk. There was no correlation between the amount of tea — after water the most widely consumed drink in the world — and the risk.

In an accompanying editorial, David Whiteman, from the Queensland Institute of Medical Research in Australia, said: “We should follow the advice of Mrs Beeton, who prescribes a 5-10 minute interval between making and pouring tea, by which time the tea will be sufficiently flavoursome and unlikely to cause thermal injury.”

Britons may also take comfort from the fact that most of us prefer our tea at between 56 and 60C.


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