Vitamin D vs. D3: What’s the Difference?

Vitamin D is a fat-soluble vitamin that supports many body processes and vital organs. It is found in certain foods and dietary supplements. The body also produces vitamin D after exposure to sunlight, which is why you may hear people refer to it as the “sunshine vitamin.”

Two types of vitamin D are essential for human health: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Although both types are referred to as “vitamin D”, there are some key differences between the two.

This article examines the differences between vitamin D and D3, their sources and roles in the body. It also discusses ways to get enough vitamin D to support your health.

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What is vitamin D?

Vitamin D is an important micronutrient for human health. One of the most important functions of vitamin D is the absorption of calcium and phosphorus, which are essential for bone mineralization and density. In addition to calcium, vitamin D helps keep your bones strong and prevents osteoporosis. Vitamin D also plays a role in:

“Vitamin D” is an umbrella term for two different forms of the vitamin: vitamin D2 and vitamin D3. Although these two forms offer the same health benefits, they are obtained from different sources and have slightly different molecular structures.

Vitamin D2

Vitamin D2, or ergocalciferol, is found in mushrooms (mushrooms) and yeasts. Vitamin D2 is produced by exposing a yeast called ergosterol to ultraviolet (UV) radiation. Foods fortified with vitamin D, such as plant-based milk, cereal and orange juice, contain vitamin D2. Vitamin D2 is also available as a dietary supplement in capsules, sublingual tablets and liquid forms.

After vitamin D2 has been ingested, it is absorbed in the small intestine and transported to the liver, which converts it into 25-hydroxyvitamin D2. From there, it turns into the active form of vitamin D (calcitriol) in the kidneys. This process allows your body to use the vitamin and reap its health benefits.

Vitamin D3

Vitamin D3, or cholecalciferol, is produced in the body when the skin is exposed to sunlight. It is also found in several animal food sources, such as fatty fish (e.g. salmon, mackerel), egg yolks and beef liver. Cow’s milk and other dairy products are often supplemented with vitamin D3. Vitamin D3 is available as a dietary supplement in liquid drops, capsules and sublingual tablets.

When you spend time in the sun, your body converts the sunlight into vitamin D3, which is then transported to the liver and converted to 25-hydroxyvitamin D3. In the kidneys, it is converted to calcitriol – the active form of vitamin D, which your body uses to support overall health.

Vitamin D2 vs. D3

Although vitamin D2 and D3 have different molecular structures, they are metabolized into the same active form of vitamin D that the body needs to support your health: calcitriol.


When vitamins D2 and D3 are converted into bioactive vitamin D, it plays a vital role in many body processes. Vitamin D promotes the absorption of calcium and phosphorus and supports bone health and muscle strength. It also boosts immune function, reduces inflammation, supports cardiovascular health and can protect against cancer.

People who don’t eat enough vitamin D-rich foods or spend too little time in the sun can have a vitamin D deficiency. Certain populations are more likely to be vitamin D deficient, including those who:

  • Have limited exposure to the sun (e.g. you live in a cold climate, you live at home)
  • Use dark skin tones because dark skin absorbs less sunlight
  • you have certain diseases that affect the absorption of vitamin D (e.g. liver disease, cystic fibrosis, celiac disease)
  • Take medications that affect vitamin D metabolism (e.g. glucocorticoids, anticonvulsants)

Signs of vitamin D deficiency

Vitamin D deficiency does not always cause symptoms. However, when it does occur, symptoms may include:

  • Fatigue
  • Muscle pain and weakness
  • Bone pain
  • Mood changes (eg.
  • Rickets (in children), where the bones weaken and cause bowed or bowed bones (eg.

Vitamin D deficiency is associated with an increased risk of fractures, diabetes, cardiovascular disease and depression. Researchers are investigating a possible link between vitamin D deficiency and inflammatory and autoimmune diseases such as multiple sclerosis and rheumatoid arthritis.


If you are vitamin D deficient, you may be wondering if vitamin D2 or vitamin D3 supplements would be better for boosting your vitamin D levels. Although vitamin D2 and D3 both increase vitamin D in the body, studies show that vitamin D3 is more effective. Vitamin D3 is absorbed by the body more easily and helps to maintain a healthy vitamin D level for long periods of time.

Although vitamins D2 and D3 are more similar than different, they can affect gene expression differently, especially with genes related to immune functions. Research suggests that vitamin D3 more effectively regulates gene expression and helps stimulate the immune system to fight bacteria and viruses to stay healthy.


The recommended dosage of vitamin D2 and D3 supplements varies based on age, weight and general health. Before supplementing with vitamin D, talk to your healthcare provider who can determine the appropriate dose for your needs.

The Recommended Daily Allowance (RDA) of vitamin D is listed in international units (IU) and micrograms (mcg) based on your age:

  • Infants 0-12 months: 400 IU (10 microg)
  • Children 1-18 years: 600 IU (15 mcg)
  • Adults 19-70 years: 600 IU (15 mcg)
  • Adults 71 years or older: 800 IU (20 mcg)

If your healthcare provider has diagnosed you with a vitamin D deficiency, they may recommend higher doses until your body’s vitamin D levels are restored.

Drug interactions and warnings

Both forms of vitamin D are considered safe and well tolerated at recommended doses. Vitamin D is fat-soluble, which means it is stored in the body. Excessive consumption can accumulate in the body and lead to vitamin D poisoning, which can harm your health. Symptoms of vitamin D poisoning include:

  • Nausea
  • Vomiting
  • Decreased appetite
  • Constipation
  • Weakness
  • Unintentional weight loss

An excessive level of vitamin D in the body also increases the blood calcium concentration (hypercalcemia), which in severe cases can cause irregular heartbeat, excessive thirst, dehydration, confusion, delirium and coma. Contact your healthcare provider if you experience these symptoms while taking a vitamin D supplement.


Vitamin D supplements can interact with certain prescription drugs or supplements and change how these drugs work in your body or cause harmful side effects. Talk to your healthcare provider before starting vitamin D therapy if you are taking any of the following medications or supplements:


Vitamin D supplementation is not recommended for everyone, and some people should exercise caution or avoid vitamin D supplementation. Do not use a vitamin D supplement if:

  • Are you allergic to aspirin or ergocalciferol (vitamin D2)
  • you have malabsorption (a disorder in which the small intestine cannot absorb enough nutrients from food)
  • you have hypercalcemia (high blood calcium)

What is the best way to get vitamin D?

Sunlight exposure and food sources are the best ways to get vitamin D as follows:

  • Exposure to sunlight: Your body converts sunlight into vitamin D when your skin is exposed to the sun. Just 10-15 minutes in the sun without sunscreen a few times a week can help your body produce enough vitamin D.
  • Dietary sources: Vitamin D is found in fatty fish, egg yolks, organ meats and fortified foods such as milk, cereals and orange juice. Getting enough vitamin D through diet alone can be challenging, especially for people who follow a vegetarian or vegan diet.
  • Supplements: Vitamin D supplements can help make sure you get enough vitamin D to support your health, especially if you have limited sun exposure or if you have trouble absorbing vitamin D from food sources.

Which is better: D2 or D3?

Vitamin D3 is converted to the active form of vitamin D (calcitriol) by ingestion or time spent in the sun. Both D2 and D3 vitamins effectively increase the vitamin D concentration in the blood. However, studies show that vitamin D3 is more easily absorbed and maintains healthy vitamin D levels better than vitamin D2.

Vitamin D3 is the form that the body produces naturally after exposure to sunlight, which may explain why the body seems to absorb and use it more efficiently than vitamin D2.

Ultimately, the best vitamin D supplement depends on your health and needs. Talk to your healthcare provider to find out which form and dose of vitamin D is best for you.


Vitamin D is an essential micronutrient that is crucial for maintaining bone health, the immune system and general health. There are two main forms of vitamin D: vitamin D2 and vitamin D3. Vitamin D3 is the form of vitamin D that the body produces after exposure to sunlight. It appears to be more effective than vitamin D2 in raising and maintaining vitamin D levels in the blood.

Vitamin D can be obtained from sunlight, dietary supplements, and dietary supplements. The recommended daily intake of vitamin D varies according to age and general health. Talk to your healthcare provider to find out which form of vitamin D is best for your needs.

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