{
  "id": 12783043,
  "title": "Scientists warn a popular vitamin D supplement may have a hidden downside",
  "url": "https://urgent.news/2026/10/08/scientists-warn-a-popular-vitamin-d-supplement-may-have-a-hidden",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-10-08T04:06:26.000Z",
  "source": {
    "name": "ScienceDaily Health",
    "slug": "sciencedaily-health",
    "url": "https://www.sciencedaily.com/releases/2026/10/261007232940.htm"
  },
  "original_language": "en",
  "account": "Scientists warn that a popular vitamin D supplement may have an unexpected downside. Research published in 2025 suggests that taking vitamin D2 could lower levels of vitamin D3, the form humans naturally produce when exposed to sunlight. Vitamin D2 and D3 are often considered interchangeable, but D3 is generally more effective at raising and maintaining blood vitamin D levels. Vitamin D is crucial for calcium absorption, bone health, muscle function, nerve function, and immune function. In the UK, people are advised to take 10 micrograms of vitamin D daily during darker months. Vitamin D supplements usually contain either D2 or D3. Traditionally, D3 came from lanolin in sheep's wool but animal-free D3 from sources like lichen is available for vegans. The study, conducted by researchers from the University of Surrey, John Innes Centre, and Quadram Institute Bioscience, reviewed 20 randomized controlled trials. They found that those taking vitamin D2 had significantly lower concentrations of vitamin D3 compared to those not taking D2. The average reduction was 9 to 18 nanomoles per liter. While vitamin D2 itself raises 25-hydroxyvitamin D2 and contributes to total vitamin D status, increasing one form seems to reduce the other. Professor Cathie Martin suggests that the findings emphasize the need for accessible plant-based and animal-free sources of vitamin D3 in the UK. The study also found that vitamin D3 stimulates a specific part of the immune system, while vitamin D2 does not. However, more research is needed to determine if these differences in vitamin D3 and D2 impact overall health.",
  "summary": "Not all vitamin D supplements are created equal, and new research suggests that one popular form may have an unexpected downside. Scientists found that taking vitamin D2 can actually lower the body's levels of vitamin D3, the form naturally produced by sunlight and more effective at boosting overall vitamin D. Previous studies also suggest that vitamin D3 may provide stronger immune protection…",
  "key_points": [
    "Vitamin D2 supplement may lower vitamin D3 levels",
    "Study by University of Surrey, John Innes Centre, and Quadram Institute Bioscience",
    "Vitamin D3 stimulates specific immune system function"
  ],
  "editors_take": "Taking vitamin D2 supplements may compromise the body's natural production of vitamin D3, potentially undermining the benefits of vitamin D for bone health, immune function, and overall well-being.",
  "illustration": null,
  "coverage": {
    "outlets": 2,
    "also_reported_by": [
      {
        "outlet": "ScienceDaily",
        "title": "Scientists warn a popular vitamin D supplement may have a hidden downside",
        "url": "https://urgent.news/2026/10/08/scientists-warn-a-popular-vitamin-d-supplement-may-have-a-hidden-12785955",
        "published": "2026-10-08T04:06:26.000Z"
      }
    ]
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}