Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Dietary Guidelines Adherence and Healthy Body Weight Maintenance Title: Total dietary fat and omega-3 fatty acids have modest effects on urinary sex hormones in postmenopausal women

Authors
item Young, Lindsay -
item Raatz, Susan
item Thomas, William -
item Redmon, Bruce -
item Kurzer, Mindy -

Submitted to: Nutrition and Metabolism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 7, 2013
Publication Date: April 23, 2013
Repository URL: http://handle.nal.usda.gov/10113/56733
Citation: Young, L.R., Raatz, S.K., Thomas, W., Redmon, B.J., Kurzer, M.S. 2013. Total dietary fat and omega-3 fatty acids have modest effects on urinary sex hormones in postmenopausal women. Nutrition and Metabolism. 10:36-42.

Interpretive Summary: Total fat and omega-3 fatty acids in the diet may affect breast cancer risk. The purpose of this study was to test the effects of total fat and omega-3 fatty acids urinary estrogens and metabolites. A controlled, cross-over feeding trial was conducted in postmenopausal women using three test diets: high fat diet (HF; 40% energy from fat), low fat diet (LF; 20% of energy from fat) and low fat, high omega-3 diet (LFn3; 23% energy from fat; 3% omega-3 fatty acids) for 8 week periods. Urinary hormone concentrations for 16 women were compared. Urinary excretion of estrone was greater after the LF and LFn3 compared to the HF. Estrone excretion was increased from baseline within the LF only. Total estrone + estradiol + estriol increased from baseline with LF. This study shows that urinary sex hormone metabolism is modestly altered in postmenopausal women by a low fat diet with or without additional n-3 fatty acids. These data support that a low fat diet increases urinary estrogen excretion, but the effects of these minimal changes on breast cancer risk are unknown.

Technical Abstract: Total fat and omega-3 fatty acids in the diet may affect breast cancer risk by altering estrogen metabolism. The purpose of this study was to elucidate the effects of differing total fat and omega-3 fatty acid content of diets on a panel of urinary estrogens and metabolites. A controlled, cross-over feeding trial was conducted in postmenopausal women using three test diets: high fat diet (HF; 40% energy from fat), low fat diet (LF; 20% of energy from fat) and low fat, high omega-3 diet (LFn3; 23% energy from fat; 3% omega-3 fatty acids) for 8 week periods. Urinary hormone concentrations for 16 women were compared among diets using a linear mixed model, and within diet comparisons were made using paired t-tests. Urinary excretion of estrone was greater after the LF and LFn3 compared to the HF (P = 0.004). Estrone excretion was increased from baseline within the LF only (P = 0.02). Total estrone + estradiol + estriol increased from baseline with LF (P = 0.02) and was greater than the other two diets at 8 weeks (P = 0.03). The results of this study indicate that urinary sex hormone metabolism was modestly altered in postmenopausal women by a low fat dietary intervention alone or with additional n-3 fatty acids. These data support previous observations that a low fat diet increases urinary estrogen excretion, but the effects of these minimal changes on breast cancer risk are unknown.

Last Modified: 11/23/2014