It’s not exactly an age-old question, but it’s an important one, especially if you care about your health. And if you’re wondering “is it better to take vitamin D3 or D2?” you’re not alone.
Let’s assume you’ve already decided that you should be getting more vitamin D. You’ve read about all the potential benefits for bone (and teeth) health, heart health, immune health, and all the other ways that vitamin D can protect and promote your health. You’re thinking about whether you need to proactively increase your vitamin D intake, beyond what you may or may not be getting from the sun’s rays.
You’re also aware that the current Dietary Guidelines for Americans, the government’s advice on what to eat and drink to meet nutrient needs, promote health and prevent disease, lists vitamin D, or actually the lack of it, as a public health concern—meaning we’re just not getting enough Vitamin D into our bodies.
And the problem exists worldwide, with some researchers calling Vitamin D deficiency a global public health issue. For instance, this recent research estimates 1 billion of us worldwide are vitamin D deficient, with ½ of the population vitamin D insufficient.
Plus, you may also know that it’s hard to get enough vitamin D from food alone. And concerns about skin cancer from spending too much time in the sun without proper sun protection means that many of us are choosing sunscreens as a preventive measure, resulting in our not even getting enough of the “sunshine vitamin” from the sun itself.
That’s where supplements, or even a prescription vitamin D drug, can come into play.
But which one? Vitamin D2 or Vitamin D3? Although they are similar molecules and each provide many of the same benefits, there are some differences between the two as well as advantages and disadvantages.
Vitamin D 101: Is it Better to Take Vitamin D3 or D2?
First, let’s quickly run through the ABC’s of vitamin D overall.
Four Things to Know About Vitamin D
- Technically, it’s not a vitamin, it’s a hormone pre-cursor, a steroid of sorts, that is categorized as one of the 13 vitamins that your body needs to function.
- It’s often referred to as the “sunshine vitamin” because when you are exposed to sunlight—specifically the ultraviolet rays (UV)—it triggers your body’s internal production of cholecalciferol, one of two forms of vitamin D.
- The fat-soluble vitamin takes two different forms: D3 (cholecalciferol) and D2 (ergocalciferol). D3 comes from animal (including people) sources while D2 is plant-based. Both are found in foods or dietary supplements, and D2 is also available in some fortified foods more commonly than D3.
- Without an adequate amount of vitamin D in your blood, you can damage your health, with deficiencies potentially leading to osteoporosis, fractures, and the rare (in the U.S.) condition (in children) known as rickets.
Why Take Vitamin D2 Over D3?
If you’re a vegetarian, D2 is for you. It’s plant-based and can be found in some fortified foods like orange juice, breakfast cereals, and plant-based milks (soy, almond, oat). Check the labels to be sure.
There aren’t a lot of conventional food sources that contain vitamin D2. Some mushrooms and yeast products, those that have been exposed naturally to sunlight or purposefully to UV radiation, can contain high levels of D2. Shiitake and portobello are thought to be good options.
There are also vitamin D2 supplements, suitable for vegans and vegetarians.
Why Do Doctors Prescribe D2 Over D3?
You may be aware that you can get your vitamin D through a doctor’s prescription and it’s usually something a doctor will recommend as a high dose, oral vitamin D regimen in order to treat deficiency or insufficiency—in short to help bring your vitamin D blood levels into the “normal” range.
A prescription-strength dose of vitamin D is typically 50,000 IU once a week for a period of time (often up to eight weeks) until your blood levels of the nutrient move into the adequate range. (Testing your blood levels is the only way to truly know if your prescription is increasing your vitamin D blood levels.) After your blood levels reach a desirable range your doctor may discontinue to prescription and suggest a vitamin D dietary supplement as a way to maintain (or continue to raise) those levels. Once again, regular testing will keep you in the right range.
Here’s the thing: while you can get a high-dose (50,000 IU) prescription vitamin D in both vitamin D2 and D3, you may find it is more readily available and easier to find in pharmacies in the D2 form; thus, the reason that many healthcare practitioners prescribe this concentrated high dose in D2, according to GoodRx Health.
It’s also likely your doctor might prescribe an oral high dose vitamin D2 regimen if you have hypoparathyroidism, hypocalcemia, osteomalacia or other specific bone diseases, chronic kidney disease; and in those cases, the dose may be even higher.
For dose comparison, over-the-counter dietary supplements of vitamin D range in daily doses of 400 IU to 10,000 IU. The RDA (Recommended Dietary Allowances) for vitamin D starts at birth at 400 IU to the first year of life, then increases to 600 IU through age 70 and increases again after age 70 to 800 IU. Some experts consider that to be too low a recommendation to achieve all the potential benefits of vitamin D.
The Tolerable Upper Intake Level for vitamin D, according to the National Academy of Medicine—the maximum daily intake unlikely to cause harmful health effects—is 4,000 IU daily for adults (and children ages 9+). Still, other experts have suggested an even higher safe upper level of 10,000 IU daily, stating that “collectively, given the absence of toxicity in trials conducted in healthy adults of > or = 250 microg/d (10,000 IU vitamin D3) supports the confident selection of this value as the UL.”
Here, at OmegaQuant, we say, yes, the dose matters, but it especially matters in conjunction with testing so you can determine if your dose is working for you by helping keep your vitamin D blood levels in adequate or optimal range. (More on that later.)
Can You Take Vitamin D2 and D3 Together?
We have to admit there is an irony involved in healthcare practitioners being more likely to recommend D2 versus D3 for raising blood levels of vitamin D. That’s because in that regard, it appears that vitamin D3 has an advantage over vitamin D2.
This article explains that while both D2 and D3 are effectively absorbed into your bloodstream, one of them—and that’s D3—does a better job of raising your vitamin D levels. Another study, this one in 32 older women, found (a very large dose of) D3 was twice as effective as (the same very large dose of) D2 in doing just that.
Other research, including this systematic review/meta-analysis of 24 studies, found that vitamin D3 is more effective in how your body uses the nutrient, specifically at raising and maintaining the vitamin D levels in your body.
And why are these studies important?
Your vitamin D status, which can be accessed through testing your vitamin D levels, with a blood draw in a lab ordered by your doctor or through at home-testing, is a means to avoid vitamin D deficiency or insufficiency and ensure you’re on track—and stay on track—with adequate (sufficient) or even optimal vitamin D blood levels.
You want to be vitamin D sufficient or at optimal levels in order to best be in a position to reap the benefits of vitamin D.
As there don’t appear to be any negative interactions between the two forms of D, the answer is “yes,” you can take them together. Because vitamin D2 may be less effective in raising your blood levels of vitamin D (and research has also shown that D3 can maintain your levels longer than D2), your doctor might recommend that you take a weekly prescribed concentrated dose of vitamin D2 and add a daily low-dose D3 supplement. Just remember to take them both with food, preferably food with some (good) fat.
Are There Other Advantages of Vitamin D3 vs. D2?
This form of vitamin D is more readily available in more foods than D2. For example, good sources of D3 include fatty fish such as salmon, tuna and herring; cheese; and beef liver; and you can also find D3 in smaller amounts in egg yolks and mushrooms. (But keep in mind, food alone may still not be enough to get you to the right blood levels of the vitamin.)
Both D3 and D2 perform the same basic functions in the body and for the most part provide many of the same benefits. There may—or may not—be a few exceptions.
For example, this fact sheet from the National Osteoporosis Foundation—now known as the Bone Health & Osteoporosis Foundation—states that while it was previously thought that D3 was a better choice than D2, more recent studies show that the two forms of D are fairly equal when it comes to bone health. But research changes, so it may have flipped back since this fact sheet was first published.
And this article states that “researchers say vitamin D3 bolsters the immune system better than vitamin D2,” noting that is in conflict with previous research that rated both forms about the same. But, then again, this piece says that one study found D3 to be more potent than D2 in regulating how the genes involved in innate and acquired immunity actually work, a nod toward D3.
That same article nodded back at D2, noting that another study gave the upper hand to that form versus D3 as being more effective for people with autoimmune conditions who were on low-dose steroid therapy.
What you’re likely to find if you search for yourself is that many experts when talking to the non-scientific community are really not actively distinguishing between the two forms, but rather urging for people to just get enough vitamin D, in general.
The one exception: the seeming consensus that vitamin D3 may just be better at raising and maintaining vitamin D levels in the body.
So, perhaps, unless you are a vegan or vegetarian, that last point alone tips the scales to D3.
The bottom line: We know that too many people are not even reaching the sufficiency levels for vitamin D, let alone optimal levels. At OmegaQuant, we offer a convenient and easy prick-of-the-finger dried blood spot test to determine your vitamin D status.
Start with a base level test so you “know your numbers.” If you are in the optimal range (30-50 ng/mL), you don’t need to change your vitamin D habits, but we recommend you retest every 6 months to make sure you stay in that range. The same is true for test results in the sufficient range (20-30 ng/mL), if you are satisfied with that level. (Note: if your results show you’re at >90 ng/mL, you might be getting too much vitamin D. Discuss that with your doctor.)
If you test at insufficient (10-20 ng/mL) or deficient (<10 ng/mL), your test results will give you some suggestions for how to raise that level. In these cases, we recommend testing once every 3 months or so to see if the changes you decide to make are making a difference. We further recommend bringing your doctor into the conversation before making any changes to your diet or supplement routine or moving to unprotected sun exposure.