Rooibos and Breast Cancer: What the early science says this Breast Cancer Awareness Month

Breast Cancer Awareness Month is a time to talk plainly about prevention, treatment, and the small daily choices that support women’s health. Rooibos, South Africa’s own herbal infusion, is part of many daily routines. New local research suggests it may have anti-oestrogenic activity in the lab, especially relevant to oestrogen receptor-positive (ER+) breast cancer. This is promising, but still early. Below is what the evidence shows so far, where it’s headed next, and how to approach it responsibly (News24, 2025; Eyewitness News, 2025; Klipopmekaar, 2025).

What The New Studies are Finding

A team at Stellenbosch University, led by Dr Nicky Verhoog, has reported preliminary results indicating that rooibos extracts can counteract oestrogen activity in ER+ breast cancer cells grown in vitro. In simple terms, the extracts appeared to blunt the effect of oestrogen that typically drives these cells to proliferate (News24, 2025). The researchers emphasise that their aim is not to promote rooibos as a cure, but to investigate whether its compounds interact with oestrogen pathways in ways that could be beneficial, and importantly, whether rooibos is safe to use in conjunction with standard care (Eyewitness News, 2025).

Several outlets summarising the work note that initial cell tests suggest rooibos may slow the growth of oestrogen-driven breast cancer cells and could act in a protective, anti-estrogenic manner, rather than mimicking oestrogen (Eyewitness News, 2025; George/Knysna Herald summaries via SA Rooibos Council, 2025). One summary further reports that in these lab conditions, the extract did not appear to interfere with tamoxifen’s action, a commonly used endocrine therapy, though this requires confirmation beyond cell models (George Herald, 2025). These signals are encouraging, but they remain pre-clinical (i.e., petri-dish stage) and must be tested in animals and then in humans before any health claims can be made (George Herald, 2025).

Klipopmekaar’s research round-up, published this month to mark Breast Cancer Awareness Month, has also highlighted the Stellenbosch findings and places them in the broader context of rooibos’ antioxidant profile and prior mechanistic research (Klipopmekaar, 2025).

What “Anti-Oestrogenic” Means in Context

ER+ breast cancers use oestrogen signalling to grow. Standard treatments often include endocrine therapies that block the oestrogen receptor or reduce oestrogen production. If compounds in rooibos are anti-oestrogenic in cell systems, they might be acting on similar pathways, for example, by reducing receptor activation or downstream signalling. Reviews of ER+ breast cancer consistently show that controlling oestrogen signalling is central to therapy, which is why any natural extract that modulates these pathways must be evaluated carefully for safety and interactions (Yadav, 2024).

Safety is Under Investigation

A key thread in the Stellenbosch programme is safety alongside existing treatments. The team has emphasised that their goal is to determine whether rooibos extract can be used safely with standard therapies. This includes checking for any dampening or potentiation of medicines such as tamoxifen or aromatase inhibitors. Early media briefings underscore that this research is in its first stages and that no clinical recommendations can be drawn yet (Eyewitness News, 2025).

The South African Rooibos Council has signposted a multi-year follow-up to move beyond cell culture into pre-clinical models to assess growth and potential metastasis endpoints, as well as pharmacology and safety. Their 2025 information brief describes the initial extracts as anti-oestrogenic in vitro and outlines plans for the next research phases (SARC, 2025).

How This Fits With What We Already Know about Rooibos

Independent of cancer research, rooibos is a naturally caffeine-free, hydrating herbal infusion with a well-studied antioxidant profile, and it is widely enjoyed hot or cold as part of a healthy lifestyle. These properties are not the same as anti-cancer effects, but they do explain why rooibos is a sensible everyday choice for many people seeking a gentle, sugar-free beverage option during treatment or recovery. Always discuss diet changes with your oncology team, especially if you are on hormone therapies.

How Carmién Supports Women and Breast Cancer Awareness

At Carmién, Breast Cancer Awareness Month is about tangible support as well as clear science. Through our CSR programme, our clinic provides regular health checks for everyone who works with us and runs ongoing educational sessions focused on women’s health and early detection. For customers, our Women’s range is designed to accompany different life stages. Examples include Feminine, Fruitful, Mom-To-Be, Nursing, and Menopause. For partners, we are fully equipped to supply rooibos internationally with our bulk rooibos solutions. If you’re developing a women’s health speciality line, our team offers blend development and product advisory through our private label services.

Practical Take-Aways for October

1. Treat the new findings as promising but preliminary. They come from cell studies, not clinical trials.
2. If you enjoy rooibos, you can continue to do so as part of your daily hydration unless your medical team advises otherwise.
3. If you are on endocrine therapy, ask your clinician about diet and herbal products, including rooibos, while we await formal interaction data.
4. Support research. The Stellenbosch programme is designed to answer the safety and interaction questions that matter most to patients (Eyewitness News, 2025; SARC, 2025).

This month is about awareness, early detection, and compassionate care. Rooibos remains a proudly South African daily ritual. The science exploring its interaction with ER+ breast cancer is moving forward, carefully and transparently. We will continue to track the evidence as it progresses from the lab bench toward clinical evaluation (News24, 2025; Klipopmekaar, 2025).

References

• Eyewitness News (2025) Stellenbosch University investigating if Rooibos extract is safe to use alongside existing cancer treatment therapies. 5 October. Available at: https://www.ewn.co.za/ (Accessed: 13 October 2025).
• Eyewitness News (2025) Maties researchers investigating whether rooibos extract has role in treating breast cancer. 6 October. Available at: https://www.ewn.co.za/ (Accessed: 13 October 2025).
• George Herald (2025) ‘Rooibos extracts demonstrate protective effects in preliminary breast cancer research’, 2 October. Available at: https://www.georgeherald.com/ (Accessed: 13 October 2025).
• Klipopmekaar (2025) ‘Rooibos extracts demonstrate protective effects in preliminary breast cancer research’, 9 October. Available at: https://www.klipopmekaar.co.za/ (Accessed: 13 October 2025).
• News24 (2025) ‘Study shows rooibos could counteract oestrogen activity in breast cancer cells’, 5 October. Available at: https://www.news24.com/ (Accessed: 13 October 2025).
• South African Rooibos Council (2025) Information sheet 2025. March. Available at: https://sarooibos.co.za/ (Accessed: 13 October 2025).
• Yadav, M. (2024) ‘Oestrogen receptor-positive breast cancer and its therapeutic approaches: a review’, Cancers, 16(4). Available at: https://www.ncbi.nlm.nih.gov/pmc/ (Accessed: 13 October 2025).