Bladder Cancer

Diet High in Certain Fruits, Vegetables, Oils Suggested

One form of vitamin E appears to offer protection against development of bladder cancer , while a second form has no beneficial effect, say a team of researchers led by M. D. Anderson.

In a five-year study, which included 468 newly diagnosed bladder cancer patients and 534 people without cancer, researchers found that high dietary intake of alpha-tocopherol, one form of vitamin E, significantly reduced the risk of developing bladder cancer.

But gamma-tocopherol, which is consumed in greater amounts than alpha-tocopherol in the United States, offered no protection, say the researchers led by Xifeng Wu, M.D., Ph.D., associate professor in the Department of Epidemiology at M. D. Anderson. The research, which was conducted by M. D. Anderson epidemiologists and nutritionists from Texas Woman’s University, was presented at the annual meeting of the American Association for Cancer Research March 27-31.

Diet tips

“High intake of vitamin E from dietary sources was associated with a 42% reduced risk of bladder cancer, whereas a high intake of vitamin E from diet and supplements combined reduced the risk by 44%,” says the study’s first author, Ladia Hernandez, research dietitian in the Department of Epidemiology at M. D. Anderson.

While the study is not over, researchers are recommending that people eat a healthy diet that includes fruit, vegetables and nuts. Many people do not eat the current recommended dietary allowance of 15 milligrams of vitamin E from their diet.

Many foods include both forms of vitamin E, including some v egetables, n uts, f ruits and o ils.

Researchers say foods richest in alpha-tocopherol include:

• Almonds
• Red and green peppers
• Spinach
• Mustard greens
• Sunflower seeds 
• Vegetable oils (including cottonseed and safflower oils)

Those high in gamma-tocopherol include:

• Walnuts
• Pecans
• Garbanzo beans 
• Soybean oil  

Previous research tentatively linked low intake of vitamin E to bladder cancer, but those studies did not distinguish between the different forms of vitamin E, which include four tocopherols. Only the alpha and gamma forms of tocopherol are predominately found in food, and because they are metabolized differently, a recent Institute of Medicine report suggested they should be studied separately.

Research process

To do that, the researchers had to develop a database for the alpha- and gamma-tocopherol contents of 200 different foods, based on an extensive review of published values and their own analytical values for foods like cornbread and french fries. These values were used to estimate the intakes of the two tocopherols in an ongoing study.

Participants answered a detailed food-frequency questionnaire that summed up their dietary habits the year before they were diagnosed with bladder cancer or, in participants without cancer, the year before they agreed to participate in the study. Researchers then factored out other known bladder cancer risks, such as smoking, age, ethnicity and gender, to determine the benefits of the two forms of vitamin E.

“Our long-term goal is to identify risk factors that are important for bladder cancer development,” Wu says.

More studies are suggesting that different vitamins protect against different forms of cancer, and some point to a benefit from gamma-tocopherol in reducing the risk of developing prostate cancer.  Scientists say, however, that more research is needed.