Wednesday, February 16, 2011

Why calorie counts don't reduce eating (because taste and price are more important)

Calorie counts on menus do not make diners eat less, research suggests. Taste, price and location were all more important.

The research was done in New York, where the display of calorie counts on menus in fast food restaurants is mandatory, but the study raises questions about the value of similar voluntary schemes in the UK.

In the study, health policy experts from New York University stopped hundreds of children and teenagers as they left fast food restaurants, before and after it became compulsory to put calorie counts on menus. The youngsters were interviewed about what they had eaten and why they had chosen that particular restaurant.

After labelling was brought in, more than half of those interviewed said they had noticed the calorie information. However, few paid any attention to it – with just 16 per cent saying it influenced their choices.

Despite what they said, displaying calorie counts had little or no effect on the amount of food eaten, the International Journal of Obesity reports. Indeed most underestimated the amount of calories they’d consumed, with many taking in almost 500 more than they realised – the equivalent of a Big Mac.

Researcher Dr Brian Elbel said his findings were all the more important because they came from a ‘real world’ setting. But he also admitted that was carried out on a relatively small number of children and teenagers, and adults tend to be more health-conscious.


Take zinc to fight a cold

Cochrane studies are unusually careful so this looks convincing. One hopes that experimenter expectation effects have been thoroughly excluded, however. The fact that studies continued after initial negative results is troubling

The best way to shake off a cold is to take supplements of the trace metal zinc, scientists say today.

While zinc is perhaps best known for protecting cars against rust, in minute quantities it has a host of important physiological functions.

Now a review of 15 clinical trials published since 1984 has concluded that taking supplements can reduce the length of a cold and help ward one off in the first place.

The conclusions of the Cochrane Collaboration, an Oxford-based not-for-profit institution that reviews existing studies to spot trends missed by looking at them individually, could lead in time to zinc replacing vitamin C as the cold 'cure' of choice.

The latest Cochrane Review found that people who took a zinc syrup solution or lozenge every two hours while they had a cold were twice as likely to have shed it within a week as those who took a placebo. Children who took a zinc tablet once a day for at least five months were also a third less likely to get colds as those who took a placebo.

The scientists concluded: "Evidence shows that zinc is beneficial for the common cold in healthy children and adults living in high-income countries. "Pooled results from the trials showed that zinc reduced the duration and severity of common cold symptoms when used therapeutically. "Zinc also reduced the incidence of the common cold, school absence and antibiotic use in healthy children."

The last Cochrane Review on zinc, in 1999, found "no strong evidence" that it had any positive effect on colds, but studies since then have forced a reappraisal.

However, the scientists cautioned that they did not yet know what dose was best, and said some zinc formulations had side effects including nausea, bad taste and diarrhoea. Because of these problems, they said it was "difficult to make firm recommendations about the dose, formulation and duration that should be used".

In the studies using zinc as a therapeutic medicine, doses ranged from 30 to 160mg per day. In the two preventive trials, one used a 15mg daily dose of zinc sulphate solution in syrup, while the other used a 10mg dose of zinc sulphate in a tablet.

Tablets containing 10, 15 or 25mg of zinc compound can easily be bought in health food shops and pharmacies. The recommended daily amount is 15mg.

Four years ago the Cochrane Collaboration concluded that taking Vitamin C supplements had no effect on most people's ability to avoid colds, although it did for particular groups under extreme physical stress.


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