A new study shows that vitamin D2 may reduce vitamin D3 levels, suggesting D3 is the more effective supplement for immune and overall health.
A new study conducted by the University of Surrey, the John Innes Centre, and the Quadram Institute Bioscience suggests that taking vitamin D2 may actually lower the body’s levels of vitamin D3, which is considered the more effective form of the nutrient. Many people use vitamin D supplements to maintain bone strength, support the immune system, and follow the UK government’s advice of 10 micrograms (µg) per day, particularly during the colder months.
Vitamin D is available in two main supplement forms: D2 and D3. The researchers observed that when individuals take vitamin D2, it can cause a decline in vitamin D3 levels. Unlike D2, vitamin D3 is the type that the body naturally makes when exposed to sunlight, and it is also the form most efficient at boosting overall vitamin D status.
The findings, published in Nutrition Reviews, are based on an analysis of randomized controlled trials. The results showed that people taking vitamin D2 experienced reduced vitamin D3 levels compared with those who did not take D2 supplements. In several cases, vitamin D3 levels dropped even lower than in the study’s control groups.
Emily Brown, PhD Research Fellow and Lead Researcher of the study from the University of Surrey’s Nutrition, Exercise, Chronobiology & Sleep Discipline, said: “Vitamin D supplements are important, especially between October and March, when our bodies cannot make vitamin D from sunlight in the UK. However, we discovered that vitamin D2 supplements can actually decrease levels of vitamin D3 in the body, which is a previously unknown effect of taking these supplements. This study suggests that, subject to personal considerations, vitamin D3 supplements may be more beneficial for most individuals over vitamin D2.”
Professor Cathie Martin, Group Leader at the John Innes Centre, said: “This meta-analysis highlights the importance of ensuring plant-based vitamin D3 is accessible in the UK.”
D2 and D3: Not Interchangeable
This research supports a previous study published in Frontiers in Immunology, led by Professor Colin Smith from the University of Surrey, which suggests that vitamin D2 and D3 do not have identical roles in supporting immune function. Vitamin D3 has a modifying effect on the immune system that could fortify the body against viral and bacterial diseases.
Professor Colin Smith said: “We have shown that vitamin D3, but not vitamin D2, appears to stimulate the type I interferon signalling system in the body – a key part of the immune system that provides a first line of defense against bacteria and viruses. Thus, a healthy vitamin D3 status may help prevent viruses and bacteria from gaining a foothold in the body.”
Further research into the different functionalities of vitamin D2 and D3 should be a priority in deciding whether vitamin D3 should be the first-line choice of vitamin D supplement, subject to individual requirements.
Professor Martin Warren, Chief Scientific Officer at the Quadram Institute, said: “Vitamin D deficiency represents a significant public health concern, especially during the winter months, with significant deficiency across the UK population. This collaborative research effort aligns well with the Quadram Institute’s mission to deliver healthier lives through food innovation to enhance the nutrient density of the food we eat. Tackling this with the most effective form of vitamin D supplementation or fortification is of the utmost importance to the health of the nation.”
Reference: “Effect of Vitamin D2 Supplementation on 25-Hydroxyvitamin D3 Status: A Systematic Review and Meta-Analysis of Randomized Controlled Trials” by Emily I G Brown, Andrea L Darling, Tracey M Robertson, Kathryn H Hart, Jie Li, Cathie Martin, Martin J Warren, Colin P Smith, Susan A Lanham-New and Ruan M Elliott, 18 September 2025, Nutrition Reviews.
DOI: 10.1093/nutrit/nuaf166
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51 Comments
Nice try
My vitamin D level got down to a 7 dr put me on 50,000 mg I could tell the difference in the way I felt
Which vitamin D did your Dr put you on? Because my doc gave me Vit D2 but now I’m not so sure if to take it.
Yes me 2 I’m on 50.000 mg of D 2 Ben taking for months now n still taken it I take 5.000 mg of B12 every day n 1.000 mg of vitamin C like 4 days a week n cromeum everyday
Yes my mother’s doctor gave her D2 and when I questioned it, they were not amused or happy.
If the Gvmt says D3 trumps D2..it’s probably false😆💥
Maybe it catalyses D2..🤷🏼
Orrr..maybe inhibits growth in tumours..🙃
Would be nice if it encouraged honesty and reduced the predatory nature in the established regime of bureaucratic sycophants and corporate parasites..👌🏼
We take D3 + K2. Don’t know of anyone who takes or recommends taking D2.
The government didn’t say anything about it.
They liked hiding the old information about vitamin D causing heart attacks. Or how they used to think it caused low iron but now they don’t. But look it people are still having heart attacks even more during the Coronavirus and anemia gets worse and worse from the supposed background radiation levels that they say are normal every time they talk about it
my dr has me taking 50,000 iu of D2 for over a year. my blood level has gone from 12 to 15.9. i too asked about D3, but she said to stay the course for now. i really am not much of a pill popper…there needs to be a reason and it needs to work.
Thanks vitamins d3 is for me
Had Psoriasis. Calf of right leg was black. Started D3, 10,000 units. Problem solved in a week. Have a small, about 1/2 by 1/2 inch, on back of my head. I use coal tar salve once a week.
I was prescribed (prescription) D2 by Hopkins for low vitamin D. A couple blood tests later I noticed the exact trend talked about above, despite eating foods like fish and getting sun, D3 levels were still low. I mentioned it to my doctor who agreed and was switched to D3 supplement. Now everything is where it should be.
Thanks vitamins d3 the one.
Yeah, not buying any of this bs.
None of us should take anybody’s word we all need to do our own research, but I know for a fact, D3 in K2 go together D2 should never ever be prescribed to anyone.
vitamins d3 the one.
My doctor was prescribing this for me to I mean I thought something was weird bou it that’s all he wanted to give me was this vitamin d now I know and now I feel weak like crazy some times
Yes I think vitamin D plays a role in our over all health mine was down to 7 took the 50,000 mg for few months I could tell a difference in how I felt after few months
50,000 per week?
Assassinate him 🥺
Not to mention that the often-prescribed synthetic D2 can be toxic. You also need to be taking K2 with your D3 for optimum effect.
Dr Kerry why do you need to also take K2 with your D3? THANK hou in advance
K2 works with D3. vitamin K2 can work synergistically with vitamin D to improve bone health. When taken together, these vitamins can help to:
Increase calcium absorption and deposition in bones
Prevent calcium from accumulating in soft tissues, such as the arteries
Reduce the risk of osteoporosis and fractures
Where can you obtain K2? Pharmacy ? Do you need prescription for it?
No – it’s available at Vitamin Shoppe, GNC, or Walmart
Any pharmacy. You really need the K2 for the vitamin D3 to bind in your body
I get it at Krogers, Walmart, Meijers grocery, vitamin stores, Walgreens. CVS, etc..
It’s solda vitamin D2 with Mk7
Alternative facts.
VA blood work said I have a vitamin D deficiency and prescribed 2000 IU of vitamin D2 . I’m not a vaccine person.
Science – arguably the most corrupt institution on planet Earth
Hmmm, at some point it can be.
🤔
just fax it 😉
👌🏼
It’s not previously unknown, it’s been known for decades. D2 competes with D3, and D3 works better.
True. Not unknown. D2 is toxic. Not sure why doctors prescribe it? To make tell people D is “useless”?
Yes me 2 I’m on 50.000 mg of D 2 Ben taking for months now n still taken it I take 5.000 mg of B12 every day n 1.000 mg of vitamin C like 4 days a week n cromeum everyday
The flat earthers on here need to go back to X.
Vitamin D2/3 are rat poison they leach calcium from bones and place in the arteries where corrtid arteries become blocked. Vitamin K2 reverses that and pulls calcium from the arteries and into the bones.
Where can I get info with proof that is correct… of what you’re saying about Vitamin K2 ?
Life extension.com, Mercola.com, pubmed
Pray to the Almighty Google and you may find your answer 🧘🏼♂️🙏🏼
Evolution has shown preference for humans that can synthesize rat poison using sunlight and cholesterol in our skin. Good to know.
In an age of Ai someone doesn’t know how to find medical studies on a specific subject. Look for studies performed by nonprofits or at least multiple research facilities with opposing political veiws/ties.
The biggest problem with science at this point is these articles that only site one viewpoint of a given subject. It’s easy to skew any research by adjusting the data used for statistics related to it. I could probably prove that the majority of people know the sun is green if I needed to.
Yes finally someone who recognizes the corruption in the science itself. Big Pharma goes with companies that give them the results they want to sell products, then they’re fined when they kill, and no one ever goes to jail, those bastards
You do know humans can’t survive without vitamin D? Rat poison lol I think you’ve paid too much attention to Trumpton.
if you cannot contribute with standard medicine research and facts, then don’t. you could say something that someone may adopt, and their health could be at risk.
D3 is good.
I take calcium and zinc as well.
Plus I make a Tumeric, Ginger, Cinnamon , Black Pepper Rosemary in a base of olive oil a couple days a week .
I like to add peanut butter for flavor.
“straight facts”
Keep taking your D3 and ignore the rhetoric above. Remember they only speak against or attack what matters.
There’s a lot of uninformed comment in this vitamin D chat. It should be moderated to weed out errors and provide more accurate information. Thanks.