High-Dose Vitamin D Doesn't Prevent Cancer or Heart Disease (But Might Help Cancer Survival?)

Overview

Paper Summary › Explain Like I'm Five › Conflicts of Interest › Identified Limitations › Rating Explanation › Good to know › Topic Hierarchy › File Information ›

Paper Summary

Paperzilla title

In a large randomized trial, daily high-dose vitamin D (2000 IU) did not prevent cancer or cardiovascular disease. However, it was associated with reduced cancer mortality after excluding the first two years of follow-up. Meta-analyses including VITAL data show similar results.

Explain Like I'm Five

Scientists found that taking a lot of vitamin D didn't stop people from getting cancer or heart disease. But, it might have helped some people who already had cancer live longer after taking it for a while.

Possible Conflicts of Interest

Pharmavite LLC and Pronova BioPharma/BASF donated the study agents and placebos. Quest Diagnostics provided lab tests at no cost. However, the NIH sponsors played a role in the study's design and interpretation, but final decisions rested with the VITAL investigators. Authors submitted conflict of interest disclosures.

Identified Limitations

Limited generalizability of findings

While VITAL was a large and well-designed trial, it focused on primary prevention and a specific dose and regimen of vitamin D. The study population might already have had sufficient vitamin D for cardiovascular health, and other doses, regimens, or studying populations with pre-existing conditions might yield different results. The lack of effect on intermediate endpoints (lipids, inflammation) after one year suggests that mechanisms by which vitamin D might influence CVD were not substantially altered in this trial.

Rating Explanation

This was a large, well-designed randomized controlled trial which addressed an important clinical question. While the primary endpoints were null for incident cancer and CVD, the signal regarding cancer mortality warrants further investigation. The transparency about limitations and funding sources strengthens the study's credibility.

Good to know

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Topic Hierarchy

Domain: Health Sciences

Field: Medicine

Subfield: General Medicine

File Information

Original Title: Principal Results of the VITamin D and OmegA-3 TriaL (VITAL) and Updated Meta-analyses of Relevant Vitamin D Trials

Uploaded: July 28, 2025 at 02:53 PM

Privacy: Public