A cheap daily vitamin pill may be giving chemotherapy a lift.
Researchers in Brazil say women with breast cancer who took 2,000 international units of vitamin D a day during chemotherapy were more likely to have their cancer disappear than women who took a placebo.
The study involved 80 women aged over 45 who were preparing to start treatment at the oncology outpatient clinic of Hospital das Clínicas at the Botucatu School of Medicine at São Paulo State University. The women were split into two groups of 40. One group received vitamin D supplements and the other received placebo tablets.
All of the participants underwent neoadjuvant chemotherapy, which is given before surgery to shrink tumours and make them easier to remove.
After six months, 43 percent of the women taking vitamin D had a complete disappearance of their cancer following chemotherapy. In the placebo group, the figure was 24 percent.
“Even with a small sample of participants, it was possible to observe a significant difference in the response to chemotherapy. In addition, the dosage used in the research [2,000 IU per day] is far below the target dose for correcting vitamin D deficiency, which is usually 50,000 IU per week,” said Eduardo Carvalho-Pessoa, president of the São Paulo Regional Brazilian Society of Mastology and one of the study’s authors.
The research was funded by FAPESP and published in the journal Nutrition and Cancer.
At the start of the study, most participants had low vitamin D levels, defined as less than 20 nanograms per millilitre of blood. The Brazilian Society of Rheumatology recommends levels between 40 and 70 nanograms per millilitre.
“With supplementation, levels increased throughout chemotherapy treatment, which reinforces a possible contribution to the patients’ recovery,” Carvalho-Pessoa told Agência FAPESP.
He said vitamin D was “an accessible and inexpensive option compared to other drugs used to improve the response to chemotherapy, some of which are not even included in the list of the Unified Health System”.
Vitamin D is best known for helping the body absorb calcium and phosphorus. The body produces it mainly through sunlight exposure, and it can also be obtained through some foods.
Current guidelines recommend 600 international units a day for most adults and 800 international units for older people. The American Academy of Pediatrics advises 400 international units a day for infants. Excessive intake can be harmful and may lead to symptoms including vomiting, weakness, bone pain and kidney stones.
The researchers said larger studies are still needed to confirm the findings and clarify how vitamin D affects the response to chemotherapy.
“These are encouraging results that justify a new round of studies with a larger number of participants. This will allow a greater understanding of the role of vitamin D in increasing the response to chemotherapy treatment and, consequently, in the greater likelihood of breast cancer remission,” Carvalho-Pessoa said.
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