In the end, Monroe and her colleagues-including Laurence N. Kolonel and Suzanne Murphy, professors at the Cancer Research Center of Hawaii, Brian E. Henderson and Malcolm Pike, professors of preventive medicine at the Keck School of Medicine of USC-looked at blood hormone levels of 252 Latina women participating in the Multiethnic Cohort Study in relation to dietary intakes. Dietary fiber intake was quantified in two ways: (1) from a food frequency questionnaire administered at the time of the blood draw; and (2) from biomarkers of dietary fiber intake found in the blood samples.
What they found was that, as dietary fiber intake increases, levels of estrone and estradiol, two female hormones measured in blood, drop sharply. In addition, the researchers say, they found that as dietary fat intake increased in the women studied, so did the hormone levels. "However, when dietary fiber and fat are both included in the statistical model, only dietary fiber remains a significant predictor of hormone levels," Monroe notes.
The next step, Monroe says, is to see if a higher intake of dietary fiber in these women leads to a lower incidence of breast cancer.
"This study provides clear evidence of an association between dietary fiber intake and circulating hormone levels in postmenopausal Latina women," the researchers note, "and potentially provides a dietary means for lowering a woman's risk of breast cancer."