Carbohydrates and Cancer

Eating a relatively 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.

For the study, lead researcher Gerald Krystal, Ph.D., a distinguished scientist at the British Columbia Cancer Research Centre 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 was a standard Western diet, consisting of approximately 55 percent carbohydrates, 23 percent protein and 22 percent fat. The second contained 15 percent carbohydrate, 58 percent protein and 26 percent fat. It was found that the tumor cells grew consistently slower in mice placed on the lower carbohydrate diet.

In addition to this, mice genetically predisposed to breast cancer were put on these same two diets. Almost half of the mice placed 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, with 70 percent of them dying from cancer. By contrast, only 30 percent of those on the low-carbohydrate diet developed cancer at all, and more than half those mice reached or exceeded their normal life span.

When asked to speculate on the biological mechanism, Krystal pointed out that tumor cells, unlike normal cells, need significantly more glucose to grow and thrive. Restricting carbohydrate intake can significantly limit both blood glucose levels, thereby limiting the food supply of malignant cells along with 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 can lead to chronic inflammation and cancer.

“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.