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Minder koolhydraten tegen kanker*
Een dieet met minder koolhydraten en meer
eiwitten lijkt goed bij kanker en in het voorkomen van
kanker, volgens een Amerikaanse studie. De studie weliswaar met muizen geeft zo’n harde biologische feiten dat volgens de wetenschappers de effecten ook voor mensen kunnen gelden. In de studie werden muizen gebruikt met menselijke tumoren en met muistumoren en speciale muizen die voorbestemd waren om ooit borstkanker te krijgen. Alle muizen
kregen of een normaal Westers dieet, 55% koolhydraten, 23% eiwitten en 22% vetten of een koolhydraatarm dieet, 15% koolhydraten, 58% eiwitten en 26% vetten. Bij de muizen met al een tumor bleek door het koolhydraatarme dieet de tumoren aanzienlijk minder snel groeiden. Bij de speciale muizen bleek in het eerste levensjaar bijna de helft van deze muizen met het Westers dieet
borstkanker te krijgen en daarentegen geen enkele muis met het koolhydraatarm dieet. Slechts 1 muis met het Westers dieet haalde een normale levensduur (ca. 2 jaar) tegen de helft van de muizen met het koolhydraatarm dieet. 70% van de muizen met het Westers dieet gingen dood aan aan borstkanker. Slechts 30% van de muizen met het
koolhydraatarm dieet kregen borstkanker.
Low-Carbohydrate, High-Protein Diets May Reduce Both Tumor Growth Rates And Cancer Risk
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.
Source:
American Association for Cancer Research (AACR) (November 2011)
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