http://www.medicalnewstoday.com/medicalnews.php?newsid=10966
New study provides support for Atkins type diet
20 Jul 2004
Was Atkins Right? New Study Provides Support For Those Who Advocate A
High Protein Diet For Weight Loss And Better Health.
Bethesda, MD – "Shape Up America," a new coalition of various health
groups recently announced their collective opinion that "booming
low-carb diets were unlikely to lead to long-term weight loss and may
be dangerous for health." At the same time, high protein diets are
attracting their share of critics, among them the American Heart
Association, which has stated that the focus on animal proteins
cholesterol raises harmful LDL cholesterol levels.
The scientific community knows that high protein diets induce early
marked metabolic changes in human and animal models, especially when
the diet contains at least 50 percent of energy as protein, but the
physiological and functional consequences of a long-term high protein
(HP) diet have not been fully explored. Now, a long-term study
involving male rats has found that a protein intake of three times the
requirements did not produce any adverse effects in key systems.
A New Study
Researchers are aware that no long-term interventional human studies
on the issue exist nor are there any complete toxicological studies on
high protein diet effects. This has led to a new investigation of the
wide range of biochemical, anatomical and histological parameters to
determine whether long-term ingestion of a high protein diet could
have adverse and/or beneficial effects in an obesity prone strain of
rats.
The authors of "A long-term high-protein diet markedly reduces adipose
tissue without major side-effects in Wistar male rats," are Magali
Lacroix, Claire Gaudichon, Celine Morens, Veronique Mathe, Daniel
Tome, and Jean-Francois Huneau, all from the Physiologie de la
Nutrition et du Comportement alimentaire, Institut National
Agronomique Paris-Grignon, Paris; and Antoine Martin, at the Service
d'Anatomie pathologique, Hôpital Avicenne, Bobigny, both in France.
Their findings appear in the Articles in Press section of the American
Journal of Physiology-Regulatory, Integrative and Comparative
Physiology. The journal is one of 14 scientific publications issued
each month by the American Physiological Society (APS)
(http://www.the-aps.org).
Methodology
This study used male Wistar rats that were administered either a no
protein diet or a high protein diet for six months. Detailed body
composition, biomarkers of oxidative stress [reduced and oxidized
glutathione, thiobarbituric acid reactive substances, expression of
glutamy-cysteine-ligase, and detoxification function
(Glutathione-S-Transferase), plasma hormones (insulin, cortisol and
leptine)] and liver and kidney histopathology were investigated.
Calcium balance was also assessed over four months after this
protocol.
Results
This study sought to estimate the consequences of a long-term intake
of high levels of protein in an obesity-prone rat strain. The results
showed that the long-term effect of eating protein at will led to a
markedly reduced food intake and lowered white adipose tissue. At the
same time, basal blood insulin, leptin and triglyceride levels, and
glucose tolerance were improved. Calcium balance was not affected by a
high intake of milk proteins.
Moreover, in contrast to what has generally been admitted, no adverse
effects of the high protein diet were reported, particularly regarding
kidney and liver health. After six months of the experiment, the body
weight of rats fed the high protein diet was 18 percent lower than
that of rats fed the non-protein diet.
Body composition measurements revealed remarkable differences between
the two groups, especially concerning the subcutaneous fat pad.
This study also revealed that the weight reduction in rats fed the
high protein diet was strongly associated with lower basal blood sugar
and insulin levels, as previously described, and improved glucose
tolerance. As the isocaloric exchange between high and low protein
diets was performed on carbohydrate, the flattening effect of the high
protein diet on insulin and glucose basal levels could be attributed
to its reduced carbohydrate content. This contrasts with the results
of many studies that have acknowledged the fact that high protein
intakes induce an increase in glucose and insulin concentrations.
Conclusions
This unique long-term study found that in male rats, a protein intake
of three times the requirements did not produce any adverse effects on
the renal and hepatic functions, on oxidative stress or on the calcium
balance. On the contrary, exchanging carbohydrates for proteins was
beneficial regarding body composition, basal triglycerides, glucose,
leptin, and insulin plasma concentrations. The results of the present
study agree with the idea that long-term dietary management is of
major importance to preventing obesity.
This study will not settle the long-standing debate regarding the
merits of a high protein diet. However, these findings will provide
support to those who advocate such a regimen for weight loss and
better health.
-end-
Source: Online edition of the American Journal of
Physiology—Regulatory, Integrative and Comparative Physiology. The
journal is one of 14 published each month by the American
Physiological Society (http://www.the-aps.org).
The American Physiological Society (APS) was founded in 1887 to foster
basic and applied science, much of it relating to human health. The
Bethesda, MD-based Society has more than 10,000 members and publishes
3,800 articles in its 14 peer-reviewed journals every year.
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Editor's Note: A copy of the research article is available in pdf
format to the press. Members of the press are invited to obtain a pdf
copy of the study and to interview members of the research team. To do
so, please contact Mayer Resnick at 301-634-7209 (direct dial),
301-332-4402 (cell) or [email hidden].
Contact: Mayer Resnick
Office: 301-634-7209
Cell: 301-332-4402
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