I recently saw the report on NBC 11.com concerning food we eat and breast cancer risk. You stated that "a half cup of corn per day is shown in research to increase breast cancer risk 25%." Then you later gave recommended servings of certain foods and gave a percentage for how much they reduce your risk of breast cancer. Can you please provide me with the research studies you are getting this information from. It would be very helpful. Thanks! Leilani
ANSWER: In Walter Willet's meta-analysis [Smith-Warner SA et al, JAMA 285 (2001) 769] it was shown that overall there are no statistically significant correlations between fruit or vegetable intake and breast cancer risk. However, some vegetables had a trend towards a positive effect, and corn had a trend towards a negative effect. Since a meta-analysis uses data from many studies, all of which were conducted differently, exact numerical values for relative risk must be interpreted with caution. That being said (and I did say this in my 1.5 hour interview with NBC, but their editing resulted in a 30-second TV spot that left much to be desired scientifically), the values from Professor Willet's study that are most interesting are as follows: The relative risk (95% confidence interval) [p value for heterogeneity between studies, with values closer to one meaning studies found completely condradictory results so the relative risk comes into greater question] are for: Broccoli 0.86 (0.72-1.02) [>0.99], Brussels sprouts 0.67 (0.35-1.27) [0.12], spinach 0.61 (0.33-1.15) [0.02], string beans 0.85 (0.66-1.09) [0.25] and corn 1.25 (0.99-1.58) [>0.99]. Walter Willet's lab also published an epidemiological study of breast cancer risk for Mexican women showing a relative risk of 2.2 (i.e. 220%, or more than double the risk) for women whose diet consisted of carbohydrate in the amount of 62% or more by calories [Cancer Epidemiol Biomarkers Prev 13 (2004) 1283]. Other researchers showed that eating 10 servings of sweets (desserts) per week as opposed to 2.5 servings per week had a 1.32 relative risk i.e. an increased risk by 32% [Potischman N et al., Cancer Causes & Control 13 (2002) 937]. We know that corn is a starchy carbohydrate (made from sugar) that digests fairly quickly (although not as quickly as a dessert). The picture that this paints is that carbohydrates when consumed in large amounts or when consumed in a form that digest and enter the bloodstream quickly contribute to breast cancer risk. It is known that large amounts of carbohydrates and sugars in particular increase insulin resistance (reduced muscle fueling, increased visceral body fat). Thus, although very sad, it comes as no surprize that insulin resistance TRIPLES breast cancer risk [Muti P. et al., Cancer Epidemiology Biomarkers & Prevention 11 (2002) 1361]. Saturated fat and excess calories also, seperately, contribute to insulin resistance. My advice is to eat refined carbohydrates (including sugars) to moderate or low levels in the diet. This would include white pasta, white bread, white rice. I would keep in moderation anything made from processed corn: Many of the cold cereals on the market, tortilla chips. I would also keep natural sweetener intake down at moderate or low levels since they also digest quickly: Honey, evaporated cane juice, 100% pure fruit-based jelly, any fruit juice. To further lower any potential insulin resistance I would reduce my saturated fat intake and reduce caloric intake consistent with a healthy body weight. The only other nutritional correlate to breast cancer that triples risk like insulin resistance is the consumption of trans fats.