I was
pretty excited to read several links in my email feed about a study just
published in The Annals of Internal
Medicine. Funded by the National Institutes of Health, it was (yet)
a(nother) randomized controlled trial (RCT), the gold standard of studies,
showing the superiority of low-carb over low-fat dieting for losing weight. For
another – and this was the hypothesis to be tested – it showed the superiority
of low-carb over low-fat in improving heart disease risk, using all the classical markers for determining that risk.
The study,
“Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial,” was
performed at the Tulane University School of Public Health in New Orleans. The
lead investigator was Lydia Bassano, MD, PhD. It enlisted a diverse population
of 148 men and women without either
clinical cardiovascular disease or diabetes. The study DESIGN: “A
randomized, parallel group trial. The OBJECTIVE: “To examine the effects of a
low-carbohydrate diet compared with a low-fat diet on body weight and
cardiovascular risk factors. The ABSTRACT can be view here. Full
access will cost you (and me) $29.95.
The study
participants were randomly selected to be placed in one of two diet groups and
had no restrictions on calories. They
were also told to make no changes in
physical activity. The target for the low carb group was to eat less than
40 grams of carbohydrate a day. The target for the low-fat group was to eat
less than 30% of daily energy intake from total fat and less than 7% from
saturated fat. Both groups received dietary counseling from an RD and were
tested at baseline, three months, six months, and twelve months. About 80% of
the participants finished the one-year study.
The
CONCLUSION was two sentences. The first is declarative and absolute: “The
low-carbohydrate diet was more effective for weight loss and cardiovascular
risk factor reduction than the low-fat diet.” The second,
“Restricting carbohydrates may
be an option for persons seeking to lose weight and reduced cardiovascular risk
factors,” is couched with the word “may.” Perhaps this is more palatable to
conventionally trained physicians (who are not trained in nutrition) and to the
nutritional professionals who are but have been misled, along with the
physicians, by half a century of poorly performed research and pure propaganda
from public health policy makers and the perfidious players in the processed
food business.
The
results, in layman’s terms, have now been broadcast widely. Jimmy Moore (Livin'
La Vida Low-Carb) and Andreas Eenfeldt (The
Diet Doctor) were among the first. But The New York Times, The Wall
Street Journal (by subscription), National Public Radio, Time Magazine, CBS News, and the Washington Post, were quick to follow.
By now the story is so widely disseminated that in some media it has been
reinterpreted to the point that it is hardly recognizable. So before or in case
a distorted version of this story reaches your ears and eyes, let me apprise
you of the principal findings.
● Triglycerides
– the type of fat that circulates in your blood – “plunged” on the low-carb
diet (NYT)
● HDL – the
so-called good cholesterol – rose more sharply than it did for people on the
low-fat diet (NYT)
● Total
Cholesterol/HDL ratio – an important maker of heart disease risk – improved
(NYT)
● Chronic
systemic inflammation – as measured by hs-CRP (C-reactive protein) also
“plunged.” (NYT)
● Blood
pressure, total cholesterol and LDL, the so-called bad cholesterol, showed
little change in both groups. (NYT)
The NYT
article was clearly open-minded and its view of the results positive. Dr. Allan
Sniderman, a professor of cardiology at McGill University in Montreal and not
associated with the study, was quoted as saying that the decrease in [heart
disease] risk on the low-carbohydrate diet “should translate into a substantial
benefit.” He added, importantly,
“One important predictor of heart disease that the
study did not assess was the relative size and number of LDL particles in the
bloodstream. Two people can have the same overall LDL concentration, but very
different levels of risk depending on whether they have a lot of small, dense
LDL particles or a small number of large and fluffy particles.”
In contrast to the very well
reported and balanced story in the New York Times, the Fox News Channel had a cardiologist on the
“Fox and Friends” program in the morning who failed to mention the first four
clearly beneficial outcomes of the trial, in terms of heart disease risk,
listed above. He did begrudgingly acknowledge, with genuine surprise it seemed
to me, that total cholesterol and LDL (the so-called bad cholesterol) stayed
about the same for people in each group. Maybe the more conservative Fox News
Network was interviewing a more conservative cardiologist. Frankly, it seems to
me that he (and most of the conservative medical establishment) has plaque on
the brain, not in their arteries.
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