[ExI] Low Carb, High Protein in Science Daily

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http://www.sciencedaily.com/releases/2011/06/110614115037.htm

Low-Carbohydrate, High-Protein Diets May Reduce Both Tumor Growth Rates and Cancer Risk

ScienceDaily (June 14, 2011) — Eating a low-carbohydrate, high-protein diet may
reduce the risk of cancer and slow the growth of tumors already present, according
to a study published in Cancer Research, a journal of the American Association for
Cancer Research.

The study was conducted in mice, but the scientists involved agree that the strong
biological findings are definitive enough that an effect in humans can be
considered.

"This shows that something as simple as a change in diet can have an impact on
cancer risk," said lead researcher Gerald Krystal, Ph.D., a distinguished scientist
at the British Columbia Cancer Research Centre.

Cancer Research editor-in-chief George Prendergast, Ph.D., CEO of the Lankenau
Institute for Medical Research, agreed. "Many cancer patients are interested in
making changes in areas that they can control, and this study definitely lends
credence to the idea that a change in diet can be beneficial," said Prendergast, who
was not involved with the study.

Krystal and his colleagues implanted various strains of mice with human tumor cells
or with mouse tumor cells and assigned them to one of two diets. The first diet, a
typical Western diet, contained about 55 percent carbohydrate, 23 percent protein
and 22 percent fat. The second, which is somewhat like a South Beach diet but higher
in protein, contained 15 percent carbohydrate, 58 percent protein and 26 percent
fat. They found that the tumor cells grew consistently slower on the second diet.

As well, mice genetically predisposed to breast cancer were put on these two diets
and almost half of them on the Western diet developed breast cancer within their
first year of life while none on the low-carbohydrate, high-protein diet did.
Interestingly, only one on the Western diet reached a normal life span
(approximately 2 years), with 70 percent of them dying from cancer while only 30
percent of those on the low-carbohydrate diet developed cancer and more than half
these mice reached or exceeded their normal life span.

Krystal and colleagues also tested the effect of an mTOR inhibitor, which inhibits
cell growth, and a COX-2 inhibitor, which reduces inflammation, on tumor
development, and found these agents had an additive effect in the mice fed the
low-carbohydrate, high-protein diet.

When asked to speculate on the biological mechanism, Krystal said that tumor cells,
unlike normal cells, need significantly more glucose to grow and thrive. Restricting
carbohydrate intake can significantly limit blood glucose and insulin, a hormone
that has been shown in many independent studies to promote tumor growth in both
humans and mice.

Furthermore, a low-carbohydrate, high-protein diet has the potential to both boost
the ability of the immune system to kill cancer cells and prevent obesity, which
leads to chronic inflammation and cancer.


Story Source:

    The above story is reprinted (with editorial adaptations by ScienceDaily staff)
from materials provided by American Association for Cancer Research, via
EurekAlert!, a service of AAAS.

Journal Reference:

   1. V. W. Ho, K. Leung, A. Hsu, B. Luk, J. Lai, S. Y. Shen, A. I. Minchinton, D.
Waterhouse, M. B. Bally, W. Lin, B. H. Nelson, L. M. Sly, G. Krystal. A Low
Carbohydrate, High Protein Diet Slows Tumor Growth and Prevents Cancer
Initiation. Cancer Research, 2011; DOI: 10.1158/0008-5472.CAN-10-3973