Jo Freudenheim, professor of social and preventive medicine in the School of Medicine and Biomedical Sciences, is an expert on the relationship between diet, environment and various types of cancer.

	Freudenheim

Your research examines the relationship between diet, the environment and disease, specifically cancer. How did you get interested in this topic?

My training originally was in nutrition. I worked for a while as a hospital and community nutritionist and then decided to go back to school for a doctorate in nutritional sciences at the University of Wisconsin. When I went, I was interested in epidemiology, based on the clinical work that I had done. Nutritional epidemiology research on chronic diseases was just developing as a field at that time. I liked the idea of doing work with a direct application to our lives. My focus on cancer came in part because of the work that I did with Saxon Graham and Jim Marshall when I arrived in Buffalo as a postdoc. They were marvelous mentors to me and because they were working in cancer, I also began to focus there. Of course, as I worked in the field, my interest grew as I talked to people with cancer, particularly women with breast cancer.

You were a co-author on the recent study published in JAMA that found that eating fruits and vegetables had no effect on the incidence of breast cancer. What does this mean?

A large number of studies examining diet and breast cancer have found that intake of vegetables and/or fruit is associated with a protective effect, that those with higher intakes have a lower likelihood of developing cancer.

This study was a group effort, putting together the data from eight large studies. The studies included more than 350,000 women. There were more than 7,000 with breast cancer. In this combined analysis, there was no evidence of the protective effect. Because this study was so large and so well designed, it clearly casts doubt on the idea that vegetable and fruit intake is associated with a protective effect. In particular, what was studied was diet close to the time of diagnosis. It may still be that fruit and vegetable intake has an effect earlier in life. There still is some evidence from smaller studies that needs to be followed up on that there may be women with genetic sensitivity that makes them more at risk when their diet is low in fruits and vegetables. There also is evidence that women who drink alcohol may be more affected by a low folate diet. Folate is found in fruits and vegetables. It also now has been fortified in grains as cereals.

In any case, this study clearly does not suggest that women should stop eating fruits and vegetables. There is evidence to suggest that a diet high in these foods is protective for some other kinds of cancer and for heart disease.

How does the lay person make sense of these types of conflicting research results?

It is important to understand that science is a process, that there is an evolving understanding of how things work. For epidemiology of chronic diseases in particular, it is very difficult to unravel the causes of disease. It may seem that something is related to disease, but in fact because so many of our behaviors and exposures are correlated, another correlated factor may be the one that is truly causing the disease.

It is probably best for the lay person to be mildly skeptical and not to react too quickly to any results that are published in the newspapers. Rather, it is important to let the evidence accumulate and act on that accumulation of information.

It seems like every other day a new study comes out labeling some other food item as being bad for you. What's a concerned consumer to do?

At this point, the diet that your grandma told you to eat still seems to be close to the right one. "Eat your vegetables, don't eat too many rich foods." Eating a variety of foods, not too many that are high in sugars or fats, eating something along the lines of the food pyramid that the USDA puts out is the most prudent approach.

Is the incidence of cancer increasing? If so, is this due solely to environmental factors?

The incidence of some cancers are increasing, others are decreasing. In some cases, the incidence is increasing because we have better screening methods and we are detecting cancers early that might have been found later or in some cases not detected at all. In other cases, there are increases that seem to be related to environmental factors, including diet and physical activity, as well as other factors in the environment. There has been a decrease in stomach cancer, though, for instance. Some people hypothesize that this change has to do with improved sanitation and refrigeration of food. Refrigeration has meant that we are less likely to eat spoiled foods and that there is increased availability of fruits and vegetables year round.

What advice can you offer for maintaining a healthy lifestyle?

I talked earlier about the dietary guidelines that make sense to me. A healthy lifestyle also certainly includes physical activity. There is a lot of information that seems to indicate that physical activity protects against the risk of some diseases, including cancer. There also is evidence that maintaining body weight through adult life, not gaining weight, is protective. Increased weight would of course be a balance between both calorie intake and physical activity. To me, too, a healthy life includes having fun, spending time with family and friends, spending time outdoors and getting some good laughs on a regular basis.

Are you a healthy eater?