Vitamin D2 vs. D3: Which One Is Right for You?

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If you need to take vitamin D supplements, you may encounter two different types on the drugstore shelf: vitamin D2 and vitamin D3. These two types are mainly differentiated by the fact that one is found in plants and the other is found in animals.

Both aid in the absorption of calcium, reduce the risk of bone loss (osteoporosis), and help prevent vitamin D deficiency. But there are subtle differences that may inform your choice.

Vitamin D Benefits

Vitamin D has multiple benefits. It is a fat-soluble nutrient, meaning it is best consumed alongside high-fat foods (much like oil, it does not dissolve in water). Vitamin D is necessary for absorbing calcium and maintaining bone health. It can help you avoid developing osteoporosis, a disease that weakens and thins your bones, increasing the risk of them breaking.

Vitamin D can help treat those with a parathyroid hormone deficiency, called hypoparathyroidism, since low parathyroid hormone levels can decrease calcium absorption. It also helps prevent rickets in children, which is characterized by softening and weakening bones due to a lack of vitamin D. Additionally, vitamin D helps your muscles move, your immune system fight off viruses and bacteria, and carry messages between your body and your brain.

Some research has linked low levels of vitamin D with a greater risk of depression, although clinical trials have not proven that vitamin D supplements can prevent or relieve symptoms.

Vitamin D2

Vitamin D2 is also known as ergocalciferol. It was first described in medical literature in 1936 and has been on the World Health Organization's List of Essential Medicines since this list was first published in 1977.

The ergocalciferol found in vitamin D2 supplements is derived from certain mushrooms (portobello, shiitake, crimini) as well as alfalfa and a type of moss known as Cladina arbuscula. When these plants are exposed to an industrial ultraviolet lamp, the ergocalciferol content increases to higher levels. Some foods are also fortified with vitamin D2.

Vitamin D3

Vitamin D3 is also known as cholecalciferol. It is the type of vitamin D found in animal sources and created naturally in the human body when skin is exposed to sunlight. It was first described in 1936 and is also on the WHO's List of Essential Medicines.

The cholecalciferol in vitamin D3 supplements is a type of cholesterol derived from the lanolin in sheep's wool. There are also vegan-friendly D3 supplements available made from lichen.

In addition to fortified foods, vitamin D3 can be found in:

  • Beef liver
  • Cheese
  • Egg yolks
  • Fatty fish (such as trout, salmon, and tuna)

Vitamin D Deficiency

Approximately one billion people around the world have hypovitaminosis D, otherwise known as a vitamin D deficiency. Most people who are deficient don't experience symptoms. However, some symptoms can include:

  • Bone pain
  • Depression
  • Fatigue
  • Headaches
  • Muscle pain

People who have limited sunlight exposure, have darker skin, have conditions that affect fat absorption, or have obesity are more at risk of developing a vitamin D deficiency and may want to consider supplementing. Older adults and children are also less likely to get enough vitamin D.

Children who are deficient in vitamin D are at risk of developing a skeletal disorder called rickets. Rickets can cause weak, soft bones, stunted growth, and deformities in severe cases.

Because vitamin D is vital for calcium and phosphorus absorption—two essential nutrients for bone health—not having enough can make it challenging to maintain proper nutrient levels in the bones. Increasing vitamin D levels by spending more time in the sun, eating vitamin D-fortified foods, or taking vitamin D supplements can help treat rickets.

If you are taking or planning to take vitamin D as a means to treat or prevent a disease, it is best to discuss the appropriate option with your doctor or healthcare provider beforehand.

Vitamin D Toxicity

It is possible to ingest too much vitamin D. High vitamin D levels are mainly the result of consuming an excessive amount through supplements. Experts agree that you cannot get too much vitamin D from the sun.

Too much vitamin D can cause:

  • Confusion
  • Dehydration
  • Excessive urination
  • Loss of appetite
  • Muscle pain
  • Nausea
  • Thirst
  • Vomiting

In severe cases, vitamin D toxicity can cause kidney failure, irregular heartbeat, and potentially death.

Which Is More Effective?

Whether you take vitamin D2 or vitamin D3, the supplement will be converted in the liver and kidneys into the active form of vitamin D.

According to research published in the American Journal of Clinical Nutrition, vitamin D3 has a potency that is between 1.7 and 3 times greater than that of vitamin D2, which means:

  • Vitamin D3 has a longer duration of effectiveness compared to vitamin D2.
  • In order to achieve equal potency and duration, vitamin D2 supplements need to be formulated up to 10 times the international units (IUs) per dose that vitamin D3 supplements are for certain health conditions.
  • Vitamin D2 supplements may have a shorter shelf life than vitamin D3.

Whether this makes one version of the vitamin "better" than the other is up for debate. Given that your body doesn't care whether it's taking more vitamin D2 or less vitamin D3—as long as it's within the recommended dose—either type could be fine if you're taking it for general health.

However, if you need it for a specific health condition, the differences between the two are relevant. According to many experts, the two supplements are not bioequivalent. If you have osteoporosis or other bone-weakening diseases (such as osteomalacia and osteopenia), vitamin D2 may not be "just as good" as vitamin D3.

At the same time, when prescribed at a 50,000-IU dose, vitamin D2 can be extremely effective in aiding in the treatment of rickets, hypoparathyroidism, and hypophosphatemia (low phosphate levels).

Vitamin D3 tends to bind more effectively than vitamin D2, which means is that vitamin D3 supplements are more potent and require lower doses to achieve the same health benefits.

A Word From Verywell

If you're at risk of osteoporosis and concerned about your vitamin D levels, the best thing to do is go to your doctor to have your blood levels checked. If they're low, you can take either form of vitamin D and, after a few weeks, have your blood checked again to see if the supplements are working.

In the meantime, try to bolster your diet with vitamin D-rich foods, such as certain mushrooms, fish, milk, and eggs, and spend ample time in the sun (with the appropriate sunblock, of course). Never exceed the recommended dose on the supplement label unless your doctor tells you otherwise.​

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