Researchers in Brazil have found that a simple vitamin D supplement may enhance the effectiveness of chemotherapy for women with breast cancer. The study, conducted at the Faculty of Medicine of the State University of São Paulo Botucatu (FMB-UNESP), suggests that low-dose vitamins may improve treatment outcomes and provide a more accessible option compared to certain expensive or difficult-to-obtain drugs designed to increase chemotherapy response.
The FAPESP-funded study involved 80 women aged 45 years and older who were preparing to start treatment at the oncology outpatient clinic of the FMB-UNESP General and Teaching Hospital (the “Hospital”). Participants were divided into two equal groups. One group received 2,000 IU (International Units) of vitamin D per day, and the other group received a placebo pill.
All women received preoperative chemotherapy. This is a treatment given before surgery to shrink the tumor and make it easier to remove.
Improving cancer disappearance rate
After 6 months, the differences between the two groups were significant. Among people taking vitamin D, 43% experienced complete resolution of their cancer after chemotherapy. In contrast, only 24% of those in the placebo group had the same results.
“Even with a small sample of participants, we were able to observe significant differences in the response to chemotherapy. Moreover, the dose used in the study (2,000 IU per day) is far below the target dose for correcting vitamin D deficiency, which is usually 50,000 IU per week,” says Eduardo Carvalho-Pessoa, president of the Brazilian Breast Society of the São Paulo region and one of the participants in the study. The authors were published in the journal Nutrition and Cancer.
The role of vitamin D in immunity and health
Vitamin D is best known for aiding in the absorption of calcium and phosphorous, which are essential for maintaining strong bones. However, there is growing evidence that it helps protect the body from infections and diseases, including cancer, and also plays a role in immune function. Many previous studies examining vitamin D and cancer focused on much higher doses than those used in the current study.
The body produces vitamin D primarily through exposure to sunlight, but it can also be obtained from certain foods. Current guidelines recommend 600 IU per day for most adults and 800 IU per day for older adults. The American Academy of Pediatrics recommends 400 IU per day for infants. Excessive intake can be harmful and cause symptoms such as vomiting, weakness, bone pain, and kidney stones.
Decreased vitamin D levels and treatment response
At the start of the study, most participants had low vitamin D levels, defined as less than 20 nanograms per milliliter (ng/mL) of blood. The Brazilian Society of Rheumatology recommends maintaining levels between 40 and 70 ng/mL.
“Taking the supplement strengthened the possibility that the levels increased during chemotherapy treatment and contributed to the patient’s recovery,” Carvalho-Pessoa told Agência FAPESP. “Vitamin D is an accessible and inexpensive option compared to other drugs used to improve response to chemotherapy, some of which are not even included in the list of the Unified Health System (Brazil’s National Public Health Network, known by its Portuguese acronym SUS),” he added.
Promising results, further research required
The findings point to a possible adjunctive role for vitamin D in cancer treatment, but the researchers caution that more data is needed. Larger studies will help confirm how effective the supplement is and reveal how it affects chemotherapy response.
“These are encouraging results that justify a new round of research with a larger number of participants. This will allow us to better understand the role of vitamin D in enhancing response to chemotherapy treatment and thus increasing the likelihood of remission in breast cancer,” he concluded.
