Weight Loss and Omega-3 Supplementation Modulate the Microbiome in Women with Increased Breast Cancer Risk

Area of Science:

• Microbiology
• Nutrition Science
• Endocrinology

Background:

• Obesity is linked to gut dysbiosis, chronic inflammation, and insulin resistance.
• Gut microbiome alterations are implicated in metabolic dysfunction and disease risk.

Purpose of the Study:

• To investigate the impact of omega-3 fatty acids on gut microbial composition during weight loss in obese women.
• To assess the association between microbiome changes and systemic biomarkers related to metabolic health and breast cancer risk.

Main Methods:

• Pilot study (n=34) of peri/postmenopausal women (BMI ≥28 kg/m2) randomized to omega-3 fatty acids (3.25 g/day) or placebo during a weight loss intervention.
• Fecal and blood samples collected; body composition assessed by DXA.
• Analysis of fecal microbial populations and plasma short-chain fatty acids (SCFAs).

Main Results:

• Participants achieved median weight loss of -10%.
• Omega-3 group showed decreased Firmicutes/Bacteroidetes ratio and increased SCFA-producing microbes (e.g., Phocaeicola vulgatus, Alistipes putredinis).
• Microbiome shifts correlated with improved breast cancer biomarkers (bioavailable estradiol, adiponectin/leptin ratio, CRP) and altered plasma SCFA profiles (increased propionate, decreased butyrate).

Conclusions:

• High-dose omega-3 supplementation, alongside behavioral weight loss, promotes beneficial gut microbiome shifts in obese women.
• These microbiome alterations are associated with improved breast cancer risk factors and metabolic biomarkers.