Mushrooms and Breast Cancer: Safety, Benefits, and Precautions

Most people with breast cancer can safely eat culinary mushrooms (such as button, shiitake, maitake) as part of a balanced, mostly plant‑based diet. ^[1] Vegetables including mushrooms are routinely recommended to support overall health for those living with or after breast cancer. ^[2] Eating mushrooms as food provides fiber and micronutrients, and this level of intake does not typically interfere with cancer treatments. ^[3]

What’s generally safe

• Culinary mushrooms in normal food amounts are considered appropriate within a plant‑forward dietary pattern for breast cancer. ^[1] Choosing a variety of non‑starchy vegetables including mushrooms fits widely used nutrition guidance for breast cancer care. ^[2]
• Nutrients are best obtained from food rather than supplements, and most people can meet their needs through a balanced, mostly plant‑based diet. ^[4] This approach lowers the risk of unintended interactions with cancer medicines. ^[5]

Potential benefits (food intake)

• Including mushrooms with other vegetables contributes to a nutrient‑dense, lower‑fat dietary pattern that can support weight management and metabolic health, which are relevant during and after breast cancer treatment. ^[3] Sample meal plans for breast cancer nutrition often feature mixed vegetables where mushrooms may be included. ^{[6] [7]}

Important precautions

• Avoid starting high‑dose mushroom extracts or herbal supplements without your oncology team’s approval, especially during chemotherapy or hormone therapy; some supplements can interact with medications or cause side effects. ^{[8] [5]}
• Grapefruit is a known food interaction with tamoxifen, so it should be avoided; this is a reminder that certain foods and supplements can alter drug levels. ^[9] While common culinary mushrooms are not highlighted as a specific interaction, concentrated supplements can be unpredictable. ^[5]
• If you take aromatase inhibitors (anastrozole, letrozole, exemestane) or tamoxifen, report all vitamins and herbal products to your clinician because these therapies have documented interactions with other drugs and supplements. ^{[9] [10] [11] [12]} Routine food mushrooms are generally fine, but high‑dose extracts should be cleared with your care team. ^[5]

Table: Food mushrooms vs. mushroom supplements

Item	Typical use	Safety during breast cancer care	Key notes
Culinary mushrooms (button, shiitake, maitake)	Cooked in meals	Generally safe in normal food amounts	Part of recommended non‑starchy vegetables in a balanced diet. [1] [2]
Mushroom extracts/capsules (e.g., high‑dose powders)	Supplement form	Use caution; avoid during chemo unless approved	Supplements may interact with therapies or cause side effects; discuss with oncology team. [8] [5]

Hormone therapy considerations

• Tamoxifen and aromatase inhibitors can be affected by other substances, and labels advise caution with co‑administration of certain medicines and herbal supplements. ^{[9] [10] [11] [12]} This underscores why concentrated, non‑food mushroom products should not be started without medical guidance. ^[5]

Practical tips

• Enjoy mushrooms as part of mixed vegetables (stir‑fries, soups, salads) a few times per week alongside other colorful produce. ^[3]
• Skip grapefruit if you are on tamoxifen due to a known interaction. ^[9]
• If you’re considering a mushroom supplement for immune support or energy, pause and check with your oncology team first, particularly during active treatment. ^{[8] [5]}

Bottom line

• Eating mushrooms as food is generally safe for people with breast cancer and can be part of a healthy, plant‑forward diet. ^{[1] [2]}
• Avoid high‑dose mushroom supplements during treatment unless your clinician specifically recommends them, because supplements can interact with chemotherapy and hormone therapy. ^{[8] [5]}
• Always review any new supplement with your oncology team, especially when taking tamoxifen or aromatase inhibitors. ^{[9] [10] [11] [12]}