Richard G. Petty, MD

Renal Cell Carcinoma and Bread

Renal cell carcinoma (RCC) is the most common type of kidney cancer, and accounts for 2 percent of all adult cancers. It has been known for some time that diet plays a role in RCC risk, but attempts to identify which foods have harmful or beneficial effects have been inconclusive.

The smart money has been on foods that elevate insulin levels, because RCC is one of the cancers associated with obesity, and some RCC cell lines grow when exposed to insulin or insulin-like growth factors.

A new study by researchers form the Institute of Pharmacological Research "Mario Negri" in Milan, conducted a large case-control study of 2301 Italians. They found a significant association between high bread consumption and renal cell carcinoma. Eating a lot of pasta and rice may also raise the risk, while eating many vegetables may lower the risk. The study published online October 20, 2006 in the International Journal of Cancer, the official journal of the International Union Against Cancer (UICC), and is available via Wiley InterScience.

The researchers enrolled 767 adults diagnosed with RCC and 1534 controls who did not have the disease between 1992 and 2004. Two controls were matched to each case by gender, age range, and location. The researchers collected sociodemographic information, height, weight, lifestyle habits and personal and family medical history from each participant. They also administered a 78-item food frequency questionnaire which asked about the average weekly consumption for each item over the previous two years. They then performed statistical analyses to discover odds ratios (OR) with a 95 percent confidence interval.

They found a significant direct association was observed for bread consumption and a higher RCC risk. A modest non-significant risk increase was also observed for pasta and rice. On the other hand an increasing intake of poultry, processed meat, and all vegetables, both raw and cooked, all reduced the risk of RCC.

These findings confirm our guess about insulin and/or insulin-like growth factors. This association between elevated cereal intake (bread, pasta and rice) is most likely due to the high glycemic index  of these foods, leading to an over-production of insulin and insulin-like growth factors.

The inverse relationship between vegetable consumption is consistent with previous studies and may be related to their content of vitamins, micronutrients or elements such as carotenoids, flavonoids and phytosterols.

This is not a perfect study: it is limited by the fact that the interviewers who gathered each participant’s information and administered the food questionnaire were not blind to who was who. But its big strengths include the sample size and the reproducibility and validity of diet information.

This study is important and speaks to the point that we have made before: a balanced diet is key, and your body does not want to be exposed to constant variations in glucose or insulin.

It also confirms all the advice that we have been offering you about what and when to eat. Click on the links to review what I have said before!

About Richard G. Petty, MD
Dr. Richard G. Petty, MD is a world-renowned authority on the brain, and his revolutionary work on human energy systems has been acclaimed around the globe. He is also an accredited specialist in internal and metabolic medicine, endocrinology, psychiatry, acupuncture and homeopathy. He has been an innovator and leader of the human potential movement for over thirty years and is also an active researcher, teacher, writer, professional speaker and broadcaster. He is the author of five books, including the groundbreaking and best selling CD series Healing, Meaning and Purpose. He has taught in over 45 countries and 48 states in the last ten years, but spends as much time as possible on his horse farm in Georgia.

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