Vitamin D2 Uses, Benefits, Sources, Side Effects, More - Dr. Axe

Fact Checked

This Dr. Axe content is medically reviewed or fact checked to ensure factually accurate information.

With strict editorial sourcing guidelines, we only link to academic research institutions, reputable media sites and, when research is available, medically peer-reviewed studies. Note that the numbers in parentheses (1, 2, etc.) are clickable links to these studies.

The information in our articles is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

This article is based on scientific evidence, written by experts and fact checked by our trained editorial staff. Note that the numbers in parentheses (1, 2, etc.) are clickable links to medically peer-reviewed studies.

Our team includes licensed nutritionists and dietitians, certified health education specialists, as well as certified strength and conditioning specialists, personal trainers and corrective exercise specialists. Our team aims to be not only thorough with its research, but also objective and unbiased.

The information in our articles is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

Does Vitamin D2 Offer Benefits? Ergocalciferol Uses, Side Effects & More


Vitamin D2 - Dr. Axe

Vitamin D — which comes in various forms, including two known as cholecalciferol and ergocalciferol (aka D3 and D2) — plays a role in bone health, immune function, growth and development, absorption of calcium, and much more. There are actually five different types of vitamin D found in both food sources and supplements, with the two most common being vitamin D2 and vitamin D3.

How do they differ, and which one is better to supplement with?

As explained more below, vitamin D2 still offers benefits, however D3 is believed to be much more absorbable. Let’s find out below where you’ll find these two different types in your diet, plus how to choose the best vitamin D supplement to help you maintain normal levels.

Vitamin D2 vs. D3

Vitamin D, an essential fat-soluble nutrient that is actually a prohormone, has been nicknamed the “sunshine vitamin” because the best way for us to obtain enough of it this essential nutrient is to expose our bare skin to the sun.

That’s right, our skin actually produces its own vitamin D when it comes into contact with UV rays. However, the key here is that you need to actually spend time in the sun regularly without wearing sunscreen for this happen.


When someone doesn’t get all the vitamin D needed from the sun plus food sources, supplements are a great backup option. When shopping for vitamin D supplements you’ll find two types: D2 and D3.

Once you take either form as a supplement, it goes through a conversion process in order to become active. Vitamin D then acts like an active hormone, binding to receptors around our bodies.

What’s the difference between vitamin D2 vs. D3?

The major differences between the two types of this vitamin are where they are sourced from and how the body absorbs them.

Vitamin D2 comes from plant sources and is not as easily absorbed, while D3 comes from animal sources.

The type of vitamin D that our own bodies make is closest to D3, also known as cholecalciferol. D3 is the “preferred type” to supplement with because it’s converted more easily to 1,25-dihydroxyvitamin D, the active form of vitamin D.


Maintaining normal levels of vitamin D is linked to better overall health and enhanced protection against certain chronic diseases—including heart disease, some types of cancer, infections, viruses and autoimmune diseases.

Some of the major benefits of vitamin D include:

  • Promoting the absorption of calcium, which is essential to maintaining bone density
  • Supporting immune defenses and normal responses to inflammation
  • Aiding in metabolism of phosphorus, which assists in maintenance of healthy tissues, bones, cells and DNA
  • Boosting mental health, supporting cognitive function and assisting in mood stabilization
  • Potentially fighting cancer development, including by slowing tumor growth and promoting cell death
  • Helping maintain a healthy body weight


Where can you find vitamin D2? It’s available naturally from certain foods, including some species of mushrooms, yeasts and fortified foods, such as cereals and milk/dairy products.

Additionally, it’s available in supplement form, most often as a capsule.

While D2 is obtained from plant foods, D3 is primarily found in animal foods, including some fish, organ meats like liver, eggs and cod liver oil.

No matter which type of vitamin D you take, including from supplements and/or food, it’s important to consume it with a source of fat, since this helps your body to actually absorb and utilize it.

Supplements and Dosage

Vitamin D supplements are a convenient way to meet your needs for this essential nutrient, particularly if you’re prone to vitamin D deficiency.

How do you know if you should supplement? It’s recommended most for people who:

  • Lack regular sunshine exposure
  • Don’t consume vitamin D food sources, such as dairy or fish
  • Have darker skin, which makes it harder for enough vitamin D to be synthesized from the sun

To help maximize absorption, it’s generally recommended to select a vitamin D3 supplement over one containing vitamin D2. However, if D2 is your only option, taking a D2 supplement can still help to bring your blood (serum) level up.


Dosage Recommendations:

Below are the recommended dietary allowance for vitamin D, depending on your age:

  • Infants 0–12 months: at least 400 international units (IU) per day
  • Children and adults 1-70 years: at least 600 IU/day
  • Adults over 70 years: at least 800 IU/day

While the amounts above are the minimum needed dosage to maintain normal vitamin D levels, consuming a higher amount of D (up to 4,000 IU per day) may be helpful for people prone to having low levels.  Speak to your doctor about the right dosage for you deepening on your medical history.

Risks, Side Effects and Interactions

Vitamin D2 (and D3) are generally safe to take and well-tolerated, but it’s still important to stick to recommended amounts to limit the risk for side effects. If you take a high dose, especially for many months,  you may potentially develop vitamin D side effects, such as abdominal pain, vomiting, nausea and confusion.

Consult with your health care provider before beginning to supplement with vitamin D if you have any underlying health conditions, especially those affecting the kidneys and thyroid.


  • Vitamin D2, also known as ergocalciferol, is a fat-soluble vitamin that is involved in bone health, immune function, cell growth and more.
  • You’ll find D2 in some mushrooms and fortified foods, such as grains and dairy products, plus supplements.
  • Compared to D3, D2 tends to be less easily absorbed. Therefore D3 is a better option when choosing a supplement.
  • The recommended daily amount is between 600 to 800 IU per day for adults, although higher doses may be helpful. Speak to your doctor if you’re prone to deficiency about how much to take each day.
  • Also boost your intake of this essential vitamin with help from sunlight exposure and foods such as fish, eggs and liver.

More Nutrition