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Diet
study raises questions about news coverage
July 24, 08
Suzanne Havala Hobbs
Recent
headlines hailed the news: The low-carb Atkins diet has been
vindicated!
Has it? No.
In fact, this episode in health news reporting is a textbook
example of journalistic failure.
If you pay attention to nutrition news, you saw the stories
about an Israeli diet study reported this month in the New
England Journal of Medicine. The two-year study, funded largely
by the Atkins Foundation, randomly assigned 322 obese people
– mostly men – into one of three diet groups:
low-fat, Mediterranean, or a low-carbohydrate diet described
as being based on the Atkins weight loss plan.
Reported weight loss was greatest among people following the
low-carb diet. Low-carb eaters also were reported to have
the greatest improvement in some blood fat levels.
The study’s bottom line: Low-carb and Mediterranean
diets may be good alternatives to low-fat diets for people
who need to lose weight.
So, what’s the problem?
Only a couple of journalists questioned key aspects of how
the study was conducted and what the results really mean.
Most news outlets simply repeated the study’s assertions,
ignoring or failing to see what should have been red flags
within the study. Among the questions that stand out:
* Did the study really evaluate the Atkins diet?
The low-carb diet used in the study was described by researchers
as being “based on the Atkins diet.” And that’s
the way most news reports described it.
But the study also said participants who followed the low-carb
diet were counseled to “choose vegetarian sources of
fat and protein.” That’s quite a contrast to the
Atkins plan described in bestselling books, which suggest
followers may eat large amounts of meat and cheese.
* Why did participants lose so little weight?
People lost weight on all three diets, but despite intensive
monitoring and coaching, participants lost an average of only
six to ten pounds over two years.
* Were the low-carb eaters the only ones told to avoid
trans fats?
Issues concerning cholesterol consumption and blood cholesterol
levels are complicated. One question about the study involves
the fact that the low-carb group was counseled to avoid trans
fats. It makes no mention of whether the low-fat or Mediterranean
groups were given similar instructions. Trans fats raise levels
of “bad” cholesterol and lower “good”
cholesterol. Is it possible that different intakes of trans
fats help explain the differences in cholesterol levels among
study participants?
* Was the low-fat diet used in the study relevant?
According to the article, members of the “low-fat”
group ate diets that got 30 percent of their calories from
fat – not a particularly low level – and their
fat intake was almost unchanged from the level consumed in
their pre-study diets.
The researchers described the study’s low-fat diet as
being based on American Heart Association guidelines. The
AHA diet guidelines were revised in 2006, while the study
was under way, a point that went unaddressed in the study.
AHA’s diet guidelines now resemble a Mediterranean-style
diet and put more emphasis on the type of fat, rather than
the amount of fat, in the diet. This reflects growing scientific
consensus that diets similar to a Mediterranean-style diet
– high in carbohydrate-rich plant foods and low in saturated
fat, trans fat, added sugars and salt, and refined foods –
are best for long-term health, including prevention of cancer
and heart disease.
At a time when obesity and diabetes rates are skyrocketing,
people need clear and sound diet advice. That includes putting
diet claims into perspective, placing them in the context
of long-term goals for overall good health.
This latest round of low-carb diet hype illustrates why the
public needs greater diligence from the news media.
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