The Surprising Mistake You’re Making When Choosing a Vitamin D Supplement, According to a New Study
October 06, 2025 | Source: Eating Well | by Shereen Jegtvig Lehman
Millions of people take vitamin D to support bone and immune health—but new research suggests the kind you choose could make a surprising difference.
A team of U.K. scientists reviewed data from clinical trials and found that vitamin D2—the plant-based version often found in fortified foods and some supplements—may actually lower levels of vitamin D3, the form your body naturally makes from sunlight.1
Vitamin D helps your body absorb calcium, keep bones strong and support a healthy immune system. Because many people don’t get enough from sunlight—especially in the fall and winter—supplements are often recommended.2
The new findings, published in Nutrition Reviews, raise fresh questions about whether the two versions of vitamin D are interchangeable. Let’s break down what the researchers found.