EFFECT OF DIFFERENT TYPES AND AMOUNTS OF FAT ON THE DEVELOPMENT OF MAMMARY-TUMORS IN RODENTS - A REVIEW

We performed a meta-analysis on data extracted from 97 reports of expe riments, involving a total of 12,803 mice or rats, studying the effect on mammary tumor incidence of different types of dietary fatty acids, Fatty acids were categorized into saturated, monounsaturated, n-6 pol yunsaturated, and n-3 polyunsaturated. We modeled the relation between tumor incidence and percentage of total calories from these fatty aci ds using conditional logistic regression and allowing for varying effe cts between experiments, and for each fatty acid we estimated the effe ct of substituting the fatty acid calories far nonfat calories. our re sults show that n-6 polyunsaturated fatty acids (PUFAs) have a strong tumor-enhancing effect and that saturated fats have a weaker tumor-enh ancing effect, The n-3 PUFAs have a small protective effect that is no t statistically significant. There is no significant effect of monouns aturated fats, n-6 PUFAs have a stronger tumor-enhancing effect at lev els under 4% of total calories, but an effect is still present at inta ke levels greater than 4% of calories. In addition, when the intake of n-6 PUFAs is at least 4% of calories, the n-6 PUFA effect remains str onger than the saturated fat effect.