People who eat plenty of fruits and vegetables may have a lower risk of developing cancers of the head and neck.

Researchers at the National Cancer Institute found that among more than 490,000 Americans age 50 and up, those who consumed the most fruits and vegetables were the least likely to develop cancers of the mouth, throat or voice box.

Smoking and heavy drinking are two major risk factors for head and neck cancers, but even when the researchers accounted for such lifestyle factors, fruits and vegetables remained linked to lower cancer risks.

Certain foods emerged as particularly protective. Legumes - including dried beans, peas and string beans - as well as peppers, tomatoes and carrots were linked to lower cancer odds. The same was true of rosaceae fruits, which include apples, nectarines, peaches, plums, pears and strawberries.

Dr. Neal D. Freedman and his colleagues report the findings in the International Journal of Cancer.

Past studies have suggested that fruits and vegetables and the nutrients they contain - including various antioxidant compounds - might help protect against head and neck cancers. But most of those studies compared cancer patients with healthy individuals, rather than following the same group of people over time to see whether fruit and vegetable intake helped predict cancer development.

For their study, Freedman and colleagues used data on 490,802 older adults who were surveyed about their diet and other health factors, then followed for 4 years. During that time, 787 men and women were diagnosed with cancers of the mouth, throat or voice box.

In general, the study found, cancer risk declined as fruit and vegetable intake climbed. For example, participants who ate the most vegetables - typically between three and four servings a day - had a one-third lower risk of developing head and neck cancers than their counterparts who ate the fewest - less than one serving per day.

A closer look at the data showed that certain fruits and vegetables were linked to a protective effect. The reasons are not clear, according to Freedman’s team. Each of the foods, the researchers say, contain “numerous potentially beneficial compounds,” and it is not possible to pinpoint which of those might be responsible.

However, they conclude, the results “support the hypothesis” that fruits and vegetables somehow offer protection from head and neck cancers.

In general, experts advise that adults strive for at least five servings of fruits and vegetables every day for the sake of their overall health.

SOURCE: International Journal of Cancer, May 15, 2008.