Vitamin D may help prevent advanced cancer in older adults

Vitamin D supplementation can reduce the incidence of advanced cancer among older adults, in particular those with a normal BMI but not those who are overweight or obese, suggests the large VITAL* randomized study presented during the ASCO 2020 Meeting.

“Our results suggest a cost-effective, safe, and accessible vitamin as a potential new prevention strategy for advanced cancer,” said lead author Dr Paulette Chandler from Brigham and Women’s Hospital, Harvard Medical School in Boston, Massachusetts, US.

“To date, no established supplement has been associated with a reduction in incidence of advanced cancer,” she added. “Even if vitamin D effects were modest, vitamin D supplementation at the studied levels are much less toxic and lower in cost than many current cancer therapies.”

“These results may have a wide-reaching, global impact, regardless of a patient’s socioeconomic status or a country’s resources,” highlighted Chandler.

Participants who received vitamin D supplementation had 17 percent lower risk of developing advanced (metastatic and fatal) cancer of any type than those on placebo (hazard ratio [HR], 0.83; 95 percent confidence interval [CI], 0.69–0.99; p=0.036). [ASCO 2020, abstract 1510]

When the analysis was stratified based on BMI, the reduction in advance cancer risk was particularly profound in participants with a normal BMI (BMI <25 kg/m²; HR, 0.62; 95 percent CI, 0.45-0.86), while those who were obese (BMI  ≥30 kg/m²) saw no protective benefit from vitamin D supplementation (HR, 1.05; 95 percent CI, 0.74-1.49; p-interaction=0.03).

In comparison, participants who were overweight (BMI ≥25 to <30 kg/m²) saw an 11 percent reduction in advance cancer risk with vitamin D vs placebo (HR, 0.89; 95 percent CI, 0.68-1.17).

“Individuals with a normal BMI derived the most benefit,” reported Chandler.

VITAL is a placebo-controlled trial with a 2x2 factorial design: participants were randomized 1:1 to receive vitamin D3 (cholecalciferol; 2,000 IU/day) supplementation or placebo; and then each arm was rerandomized 1:1 to 1 g daily supplements of marine omega-3 fatty acids or placebo for a median duration of 5.3 years. Participants were 25,871 healthy men (≥50 years) and women (≥55 years) who were free of cardiovascular disease and cancer at baseline. A total of 1,617 patients developed invasive cancer during follow-up. 

There was no significant difference in advanced cancer rates among patients receiving omega-3 supplementation vs those on placebo (HR, 0.97, 95 percent CI, 0.81-1.15; p=0.72).

Explaining on the potential reason why obese individuals did not derive a protective benefit from vitamin D supplementation, Chandler suggested that the bioactivity of vitamin D might be decreased in these individuals due to volumetric dilution.

“Whether overweight/obese persons require higher doses to derive cancer benefit, analogous to body size differences in aspirin dosage requirements, should be evaluated,” she said.

*VITAL: The VITamin D and omegA-3 triaL