Estrogen-positive (ER+) breast cancer is fueled by estrogen, meaning treatments often focus on lowering or blocking this hormone. According to the American Cancer Society (ACS), Breastcancer.org, and the National Cancer Institute (NCI), dietary choices may influence hormone levels and overall health during treatment. While no food directly causes or cures breast cancer, certain foods are best limited or avoided for women with ER+ breast cancer.

Foods to Avoid with Estrogen-Positive Breast Cancer

1. Alcohol

Even moderate alcohol use increases estrogen levels and breast cancer recurrence risk.
The American Cancer Society advises women with ER+ breast cancer to limit or avoid alcohol entirely.

2. Processed and Red Meats

High in saturated fat and linked to increased inflammation.
Studies suggest a higher intake of processed meats (like bacon, sausage, deli meats) may raise recurrence risk.

3. High-Fat Dairy Products

Whole milk, cheese, and butter are high in saturated fats, which may influence estrogen metabolism.
Low-fat or plant-based alternatives are often recommended.

4. Foods High in Added Sugars

Excess sugar contributes to weight gain and higher insulin levels, which may affect hormone-related cancers.
Sodas, pastries, and candy should be minimized.

5. Soy Supplements (But Not Whole Soy Foods)

Concentrated soy protein powders or isoflavone supplements may act like estrogen in the body.
Whole soy foods (tofu, edamame, soy milk) appear safe in moderation, per research, but supplements should be avoided.

6. Highly Processed Foods

Packaged snacks, fried foods, and fast food often contain trans fats and additives that negatively affect overall health and recovery.

7. Phytoestrogen-Rich Seeds and Grains

Flax, sesame, and certain soy products contain plant estrogens; whole food sources in moderation are generally safe, but concentrated forms should be avoided.

8. Deep-Fried Foods and Trans Fats

Oils used in deep frying increase inflammation and can interfere with hormone balance.

9. Certain Fish and Shellfish

Some fish may contain estrogen-like contaminants or heavy metals that affect hormone health.

10. Grapefruit (for Patients on Medication)

Grapefruit can interfere with breast cancer drugs such as tamoxifen by altering how they are metabolized.

Key Takeaway

Women with ER+ breast cancer should focus on a diet rich in vegetables, whole grains, fruits, lean proteins, and healthy fats, while limiting alcohol, processed meats, high-fat dairy, and added sugars. Always consult with your oncologist or a registered dietitian for personalized guidance.