After a decade of research with over a million people, the results are in: Eating lots of fruit and vegetables may not reduce your risk of developing cancer. Far better, researchers say, is to cut down or eliminate smoking, heavy drinking and drug use. Eliminating these carcinogenic influences can boost your body's resistance to ward off diseases like cancer. Maintaining a healthy weight and exercise also helps.
According to Tim Key, an epidemiologist from Oxford University, who summarized his findings in British Journal of Cancer, the amount of fruit and vegetables people eat has little to do with their overall cancer risk "” including cancers of the gastrointestinal tract, lung and breast. While one needs fruits and vegetables to prevent nutrient deficiencies, consuming large amounts of these foods won't make you "super healthy."
Early, small-scale studies in the 1970's showed that the consumption of fruits and vegetables could reduce cancer risk. But those studies involved participants who also cut back on smoking. Key notes that a major problem lies with how people are selected for these study control groups. Those eager to participate may already be following healthy behaviors. And those with unhealthy diets often don't volunteer for these studies.
A more accurate way to judge the relationship between diet and cancer is through "prospective studies." Key suggests that such studies ideally follow thousands of people who are cancer free. Researchers need to look at what they eat and follow them until some develop cancer. You also need to exclude smokers, heavy drinkers, drug users and those who are perennially obese.
Regardless of what these studies report, most doctors recommend that people eat their minimum daily requirement of fruits and vegetables (up to 5 portions). This can help people lose weight, and obesity is a major contributor to cancer. What's more, several studies show that eating vegetables regularly may lower your risk for cardiovascular disease. And that certain vegetables contain potent, cancer-fighting compounds. There's also a higher cancer fighting benefit for heavy drinkers who eat vegetables.
Keep in mind too, that some study results may not reflect the ability of specific types of vegetables and fruits in reducing cancer risk, such as howlycopene from tomatoes may lower prostate cancer risk. Many studies also focused on vegetable consumption during adulthood, not childhood and the teenage years, which may have an impact.