Vitamin D Alert: Common Supplement May Hinder, Not Help, Levels, Study Finds

Wednesday - 08/10/2025 00:16
New research indicates that Vitamin D2 supplementation may actually lower the body's natural Vitamin D3 levels. While both forms are used, Vitamin D3 is now believed to be significantly more effective at sustaining levels over time. This finding is crucial for those at risk of deficiency, highlighting D3 as the preferred choice for supplementation.
This common supplement could lower vitamin D levels in the body, says study
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Vitamin D, the star vitamin, also known as the "sunshine vitamin", is widely recognised as one of the most important nutrients for maintaining strong bones, a resilient immune system, healthier body organs, and overall well-being. As many people are getting aware of the necessity of this vitamin, it is important to understand to the CORRECT form of this vitamin. With less sunlight year-round, especially in colder months, millions turn to supplements to maintain healthy levels of this essential vitamin.But according to new research, the type of vitamin D we choose make a significant difference, so much so that one common form may actually lower the levels of the other in the body.A recent meta-analysis published in the Nutrition reviews shed light on the ongoing debate between Vitamin D2 that is ergocalciferol and vitamin D3 called as cholecalciferol, while both are used in supplements and fortified foods, scientists now believe they may not be equally effective, and in fact, may not be interchangeable at all!

Vitamin D2 vs D3: What's the difference

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Vitamin D exists in two main forms:Vitamin D2: Typically, a plant-based sort of vitamin that is found in fungi food items such as mushroom. It's also the form most commonly used in food fortification and many vegan supplements as wellVitamin D3: Our skin naturally produces this vitamin, as strange as it sounds, when our skin is exposed to sunlight, and then our skin absorbs this. It is also found in animal-based foods like fish, egg yolk, and liverFor years, it was believed that vitamin D levels in the blood were raised by both of these forms of vitamin D, but recent study points out that vitamin D3 may be significantly more effective at sustaining those levels over time.

The study in question:

A team of UK researchers from the University of Surrey and partner institutions set out to answer an important question: Does taking vitamin D2 affect vitamin D3 levels in the body?The randomised controlled trials started out from 1975 and were conducted until 2023, almost 50 years. Out of 202 identified articles, they only selected 11 high-quality studies that directly measured vitamin D3 levels in participants who had taken D2 supplements.

The results concluded were astonishing:

Participants who took vitamin D2 experienced an average drop of 18 nanomoles per liter in their vitamin D3 levels by the end of the study period.Even when broader changes were considered, the overall reduction was around 9 nanomoles per liter.This pattern was consistent across multiple trials, suggesting a clear biological interaction-vitamin D2 supplementation appears to reduce the body’s natural vitamin D3 levels.

Does vitamin D matter that much for your health?

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Yes! Vitamin D3, is known as the most accessible and easier way to hype your vitamin D levels in the body:They play a huge role in mood, muscle function and inflammation controlThey regulate the immune system, helps defend against infectionsHelps the body to absorb calcium, better there by better bone health.

What happens if: One takes D2 more than D3

In simpler terms, if one takes more D2 instead of D3, it may mean your body is not getting the full effects of vitamin D, even if the overall vitamin D levels in the body are fine, lab result numbers are also apt. This is especially concerning for people at the RISK of deficiency, such as those who are living in low-sunlight regions, older adults, and people with autoimmune diseases.

Natural sources of vitamin D

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Food alone is not sufficient! But some natural and fortified sources are as follows:
  • Milk products (includes, plant based milk, yogurt, cereal etc)
  • Mushrooms (after being exposed to UV light)
  • Fatty fish (the most readily available source)
  • Egg yolk (if one cannot or does not consume fish)

What should we do

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This research suggests that vitamin D3, is a better choice for supplementation, if ones goal is to raise and maintain the already existing vitamin D levels in the body. It appears more stable, more effective and less likely to disrupt the body's natural D3 balance.For those who are vegan: Good news! They can obtain D3 from lichen, widely available and performs similar to standard D3.If one is looking to maintain bone health, immunity or overall wellness, it's worth choosing the form backed by stronger evidence. Vitamin D3 remains the gold standard offering more consistent support for health.


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