Estrogens, breast cancer, and intestinal flora

Area of Science:

• Endocrinology
• Gastroenterology
• Oncology

Background:

• Epidemiologic studies link high-fat, low-fiber diets to increased breast cancer rates.
• Estrogens are implicated in breast cancer development.
• Dietary factors influence estrogen levels, primarily via intestinal metabolism.

Purpose of the Study:

• To investigate the role of intestinal microflora in estrogen metabolism and its relation to diet.
• To explore the mechanism by which diet affects estrogen enterohepatic circulation.

Main Methods:

• Antibiotic therapy was used to suppress intestinal microflora.
• Fecal and urinary estrogen levels were measured before and after microflora suppression.
• Dietary interventions (low-fat, high-fiber) were studied in relation to estrogen excretion patterns.

Main Results:

• Antibiotic treatment led to increased fecal estrogens and decreased urinary estrogens, indicating reduced reabsorption.
• A low-fat, high-fiber diet mirrored these changes, with high fecal and low urinary estrogens.
• These findings suggest the intestinal microflora is crucial for estrogen enterohepatic circulation.

Conclusions:

• The intestinal microflora plays a pivotal role in metabolizing and reabsorbing estrogens.
• Dietary interventions, particularly low-fat, high-fiber diets, can modulate estrogen metabolism via the gut microbiome.
• Understanding this interplay may offer strategies for breast cancer prevention.