Vitamin D vs D2 vs D3: What's the difference between them?

Vitamin D (also known as calciferol) is an important nutrient that your body needs to absorb calcium, fight off infections, and to move your muscles. It has many other roles in the body as well. When your skin is exposed to the sun, your body makes vitamin D. Some foods contain vitamin D naturally, while others are fortified with vitamin D. When people are not able to make enough vitamin D, supplements can help raise vitamin D levels in the body.

The two forms of vitamin D found in foods and dietary supplements include ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). While both forms of vitamin D raise vitamin D levels in your blood, vitamin D3 might increase it more and for a longer period of time compared to D2. The active form of vitamin D is called 1,25-dihydroxycholecalciferol (also known as calcitriol), and is available with a prescription.

Another form of vitamin D, 25(OH)D₃, has been used in studies and is thought to be three to five times as strong as vitamin D3. Currently, there are not any dietary supplements available that contain 25(OH)D₃.

How is vitamin D made?

The natural form of vitamin D we get from sun exposure is vitamin D3. When the skin is exposed to ultraviolet rays in sunlight, a substance called 7-dehydrocholesterol is converted to vitamin D3. The liver and kidneys convert vitamin D3 into the active form that our bodies can use.

Vitamin D2 and vitamin D3 that are found in supplements are made differently:

• Vitamin D2 is made using UV irradiation of ergosterol in yeast. If you follow a vegan or vegetarian diet, vitamin D2 supplements are a suitable option.
• Vitamin D3 is made using irradiation of 7-dehydrocholesterol from lanolin (from sheep wool). It is also made from lichen and marketed as vegan or animal-free when it is sourced this way.

No matter which form of vitamin D you take (vitamin D2 or D3), they both need to get converted into the active form of vitamin D in your body. This happens in two steps. First, the liver converts vitamin D2 and D3 into 25-hydroxyvitamin D. Then, the kidneys convert 25-hydroxyvitamin D into the active form of vitamin D, calcitriol.

Are vitamin D2 and vitamin D3 found in foods?

Not many foods contain vitamin D naturally, and many foods are fortified with vitamin D. This means vitamin D is added to the food. Small amounts of vitamin D3 are found in beef, salmon, cheese, eggs, and liver. Many milks and cereals are fortified with vitamin D3. Vitamin D2 can be found in mushrooms, but the amounts vary.

Does vitamin D2 or vitamin D3 work better?

Both vitamin D2 and vitamin D3 are well absorbed after taking them by mouth, whether they are taken in food, drinks, or dietary supplements. They can also both successfully cure rickets, a condition caused by low vitamin D levels. However, evidence suggests that vitamin D3 raises vitamin D levels higher and maintains them longer when compared to vitamin D2. For most people, it does not matter which form of vitamin D you take.

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Do I need a prescription for vitamin D2 or vitamin D3?

Both vitamin D2 and vitamin D3 can be found over the counter in different strengths. They are commonly available as capsules and as an oral liquid, but are in other forms as well. Many times, vitamin D is combined with other vitamins and minerals in supplements found over the counter. Higher strengths of vitamin D or injectable forms require a prescription from a healthcare provider.

What are the side effects of vitamin D2 and vitamin D3?

Side effects from taking vitamin D at recommended doses are rare. You may notice a metallic taste in your mouth with some forms, or get an upset stomach if you are sensitive to pills. It is more common to experience side effects with higher doses of vitamin D. This might be a sign that you are taking too much.

Contact your healthcare provider if you feel nauseous, are eating less, feel more thirsty, or experience muscle weakness. These are all signs of taking too much vitamin D.

Is too much vitamin D bad for you?

Yes. Too much of any form of vitamin D is toxic, because this can lead to too much calcium in the body.

Symptoms of having too much vitamin D in the body include:

• Nausea
• Vomiting
• Muscle weakness
• Confusion
• Poor appetite
• Feeling thirsty
• Excessive urination

Having too much vitamin D in your body can also lead to kidney stones and irregular heartbeat.

Adults should not take more than 100 mcg (4,000 IU) of vitamin D per day unless they are under the supervision of a healthcare professional. The maximum recommended daily amount for children depends on their age, so ask your child’s healthcare provider about what a safe amount for them is to take.

Your healthcare provider may recommend taking a higher dose of vitamin D than what is typically recommended if you have certain medical conditions.

Is it OK to take vitamin D2 or D3 everyday?

Yes, as long as you do not take more than the maximum recommended amount of vitamin D each day. Since many people do not get enough vitamin D from the sun, it can be helpful to take a vitamin D supplement every day. If you are pregnant or breastfeeding, it is recommended to take a daily vitamin D supplement between September and March when people typically do not get enough vitamin D from the sun.

Ask your healthcare provider if taking a vitamin D supplement daily is right for you. They can help you determine the ideal daily amount of vitamin D required for you based on your age and health conditions.

If you have questions about which form of vitamin D would work best for you or what dose you should take, talk to your healthcare provider.

Read Next → The Vitamin D Guide