Low Carbohydrate, High Protein Diet Slows Tumor Growth

A new study suggests that a low carbohydrate (CHO) diet not only restricts weight gain but also slows cancer development and progression.

Researchers at the British Columbia Cancer Research Center (BCCRC; Vancouver, Canada) compared the effects of low CHO diets to a Western diet on the growth rate of tumors in a mouse model. To avoid caloric restriction–induced effects, the low CHO diets were designed to be of an isocaloric value with the Western diet by increasing protein rather than fat levels, due to the reported tumor-promoting effects of high fat and the immune-stimulating effects of high protein.

The researchers found that both murine and human carcinomas grew slower in mice on diets containing low amylose CHO and high protein, compared with a Western diet characterized by relatively high CHO and low protein. There was no weight difference between the tumor-bearing mice on the low CHO or Western diets. Additionally, the low CHO-fed mice exhibited lower blood glucose, insulin, and lactate levels. Strikingly, in a genetically engineered mouse model of mammary cancer, tumor penetration in mice on a Western diet was nearly 50% by the age of one year, whereas no tumors were detected in mice on the low CHO diet; this difference was associated with weight gains in mice on the Western diet not observed in mice on the low CHO diet. Moreover, whereas only one mouse on the Western diet achieved a normal life span, due to cancer-associated deaths, more than 50% of the mice on the low CHO diet reached or exceeded the normal life span. The study was published in the July 1, 2011, issue of Cancer Research.

“A high amylose containing low CHO, high protein, diet reduces blood glucose, insulin, and glycolysis, slows tumor growth, reduces tumor incidence, and works additively with existing therapies without weight loss or kidney failure,” concluded lead author Victor Ho, PhD, and colleagues. “Such a diet, therefore, has the potential of being both a novel cancer prophylactic and treatment, warranting further investigation of its applicability in the clinic, especially in combination with existing therapies.”

Amylose is a polysaccharide made up of D-glucose units. It is one of the two components of starch, making up approximately 20%-30% of the structure; the other component is amylopectin, which makes up 70%-80% of the structure. Because of its tightly packed structure, amylose is more resistant to digestion than other starch molecules and is therefore an important form of resistant starch, which has been found to be an effective prebiotic. High-amylose varieties of long-grain rice have a much lower glycemic load, which could be beneficial for diabetics.

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British Columbia Cancer Research Center