Bananas, root veggies may cut kidney cancer risk

People who like their bananas, carrots and beets may have a lower risk of developing kidney cancer than those who turn their noses up at the foods, a large Swedish study suggests.

Some past studies, though not all, have shown that diets rich in fruits and vegetables may help stave off kidney cancer. The new findings, based on dietary information from 61,000 Swedish women, zero in on certain foods - namely, bananas, root vegetables, salad greens and cabbage - that may confer such a benefit.

The study found that a high overall intake of fruits and vegetables was related to a lower risk of kidney cancer, though the effect was not significant in statistical terms. There were, however, significant effects when it came to certain foods.

Women who ate bananas four to six times a week, for example, had about half the risk of kidney cancer as those who did not eat the fruit. Regular consumption of root vegetables, including carrots and beets, was linked to a 50 percent to 65 percent decrease in risk.

There are about 190,000 cases of kidney cancer diagnosed worldwide each year. Research has uncovered a number of risk factors - including smoking, obesity, high blood pressure and occupational exposure to certain chemicals, such as asbestos and cadmium. But studies on diet have been inconsistent.

The new study is the largest to show an association between kidney cancer and fruit and vegetable intake, according to lead author Dr. Bahram Rashidkhani of the Karolinska Institute in Stockholm.

It adds to the body of research, he told Reuters Health, by suggesting that it's the consumption of particular foods, rather than total fruit and vegetable intake, that may matter.

The study, reported in the International Journal of Cancer, included 61,000 women ages 40 to 76 who were followed for an average of 13 years. At the start of the study, the women completed dietary questionnaires, reporting how often during the past 6 months they had eaten various foods. During the follow-up period, 122 women developed renal cell carcinoma, by far the most common form of kidney cancer.

Besides bananas and root vegetables, white cabbage - widely consumed in Sweden - and "salad vegetables," including lettuce and cucumber, were linked to a lower cancer risk.

The associations held up when Rashidkhani's team calculated the effects of other factors, such as age, weight and smoking.

Bananas, Rashidkhani noted, contain an especially high amount of antioxidant compounds called phenolics. For its part, white cabbage contains isothiocyanates, chemicals that lab research suggests may fight tumor formation.

There were a number of fruits the study did not consider because of their lack of popularity in the study population; these included peaches, plums, grapes and berries.

And when it came to fruit juice, the researchers found that high intake was associated with a greater risk of kidney cancer. The reason for the link, according to Rashidkhani, is unclear, and it could be just a "chance" finding.