Eating lots of bread may increase kidney cancer risk

An Italian study that compared the food intake of kidney cancer patients to those without the disease reports that a diet high in bread may increase the risk of contracting the deadly ailment.

Researchers say people who consume the highest amounts of bread double the risk for kidney malignancy， compared to those eating the smallest amounts.

But an American expert warned the findings are not based on enough information and more studies should be undertaken.

“These findings need to be replicated and found consistent before any recommendation can be made，” Marji McCullough， a registered dietitian and spokeswoman for the American Cancer Society， said in a prepared statement.

The study's lead author， Francesca Bravi， a researcher at the Mario Negri Institute for Pharmacological Research in Milan， agreed. Her team published the findings in the Oct. 20 online edition of the International Journal of Cancer.

“Further studies are needed to confirm the link between bread and renal cell [kidney] carcinoma，” she said.

Bravi's team compared 767 men and women， aged 24 to 79， with kidney cancer to 1，534 men and women in the same age range who did not have the disease.

They asked about diet， lifestyle， personal and family medical history and obtained the participants' height and weight so they could compute their body-mass index （BMI）。 The participants also answered questions on average weekly intakes of 78 food items over the past two years.

Those who ate the highest amounts of bread —— 28 portions a week —— had nearly two times the risk of kidney cancer as those who ate the lowest number of portions per week， 9， she found.

A “portion” was defined as 50 grams or 1.7 ounces， the equivalent of a slice or a slice and a half of bread.

A modest but not statistically significant increased risk was found for the highest intakes of pasta and rice. Those with the highest intakes of milk and yogurt had a 1.3 times greater risk for kidney cancer， she found. But high intakes of poultry， processed meet and vegetables decreased the risk

McCullough said is was possible that it wasn't the bread consumption that raised the risk of cancer， but something related to it， such as eating a lot of butter with the bread.

Bravi speculated that the elevation in risk linked to high bread， pasta and rice consumption could be due to the blood-sugar raising effects of these foods.

Eating large quantities of those foods， she said， may affect the process of getting cancer by influencing the level of substances called insulin-like growth factors， which have been implicated in cancer.

“Our study suggests that a diet poor in refined cereals and rich in vegetables may have a favorable role on the risk of renal cell carcinoma，” Bravi said.