October is Breast Cancer Awareness Month, and there’s some good news on the horizon in South Africa. Stellenbosch University’s Dr Nicky Verhoog is leading a study to assess the impact of Rooibos extract in breast cancer treatment. Early results suggest Rooibos extract may limit estrogen's role in promoting breast cancer cell growth.
In 2023, Harvard Medical School reported that estrogen stimulates breast tissue division and rapid multiplication, raising the risk of cancer-causing mutations.
The Knysna-Plett Herald reports Rooibos extract showed reactions to estrogen similar to fulvestrant, a drug used to block estrogen in breast cancer treatment.
The extract was found to slow down estrogen-induced cell growth and prevent the cells from spreading.
Mahtaab Hayat and Jean-Tristan Brandenburg 5 Sep 2025 "Our recent research has found that Rooibos extract may counter the effects of estrogen in breast cancer cells.
“Estrogen is known to fuel the growth of many breast cancers, making these early findings especially significant.
“In laboratory tests, we found that Rooibos slowed down the growth of estrogen-driven breast cancer cells and stopped them from spreading," Verhoog told Eyewitness News.
While these findings are encouraging, the researchers say they don’t intend to find a cure, but rather to determine if rooibos is safe to use alongside well-established treatments.
The next step is additional studies on animals, which are scheduled for 2026.
Verhoog says that because the lab studies are focused on single cells, they can’t replicate the complexity of the human body.
“We need to see how Rooibos behaves when metabolised in the body,” she says.
Given the potential for a breakthrough in breast cancer treatment, the South African Rooibos Council (SARC) and the Department of Science and Innovation (DSI) Sector Innovation Fund Programme are supporting the research.
