At a hospital in São Paulo state, Brazil, 80 women over 45 years old were preparing for chemotherapy to treat breast cancer. Half of them received vitamin D pills every day, while the other half received a placebo. Neither the patients nor their doctors knew which group was which.
After six months, the results were surprising. Women who took 2,000 international units of vitamin D daily were nearly twice as likely to have no detectable cancer remaining before surgery. In the vitamin D group, 43% had a complete response, meaning doctors found no remaining cancer. In the placebo group, only 24% achieved this result.
The trial was conducted at the Botucatu School of Medicine of São Paulo State University, one of Brazil's leading medical schools. Most women in the study started with low vitamin D levels. After six months of treatment, the vitamin D group's levels improved significantly.
The findings are important because breast cancer is the most common cancer worldwide. Many effective cancer treatments are expensive and unavailable in public health systems. Vitamin D, however, is cheap and available in pharmacies everywhere. Researchers plan to conduct a larger study to confirm these results in different populations. The discovery could help millions of patients who cannot afford expensive treatments.