Written by Pliro
Jul 15, 2019 Last updated: Jul 17, 2019

When someone mentions vitamin D they really are not talking about a single thing. Vitamin D is a family of compounds originally composed of: D1, D2 and D3. Over the years it became clear that D1 wasn’t actually a single thing, but a mix of different reagents, so, at the moment only D2 and 3 exist officially.

D2 and D3 are very similar and in essence they have the same function in the human body. Manly, vitamin D is needed for calcium (Ca+2) to be absorbed to the bones and for it to be retained for long periods of time (prevents loss of calcium), without this vitamin the bones would become weaker over time.

Specific Functions of Vitamin D

  • Maintenance of bone strength
  • Regulation of blood levels of calcium and phosphorus
  • Normal muscle function
  • Regulation of the immune system

Health Benefits of Vitamin D

Vitamin D should be used with care; its excess in blood can cause a lot of problems that would make any benefit irrelevant.

The main benefits of maintaining normal vitamin levels include:

  • Protection of bones and prevention of osteoporosis
  • Diabetes prevention
  • Prevention of dementia
  • Prevention of cancer (specially in postmenopausal women)

D2 or D3: Which is better?

As we mentioned before, D2 and D3 belong to the vitamin D family. They have many similarities, in fact, many sources don’t even make a distinction between these chemicals, but they have differences that may be important if you are planning to take vitamin D supplements.

  1. Vitamin D2 is called ergocalciferol while D3 is cholecalciferol   
  2. D2 is found only in plants while D3 is only found in animals
  3. Humans get a great part of the D3 they need not from their diet but from the sun. When human skin is exposed to sunlight it produces D3 naturally
  4. D3 is 3 times more potent than D2 and therefore is preferred for medical purposes
  5. The effects caused by D3 last longer

WARNING: D3 is recommended as a supplement for people with vit D deficiency, but it should not be taken without medical supervision or if you suffer from an allergy to D3, problems with the absorption of nutrients or have abnormally high blood levels of calcium. Pregnant women and people with a heart or kidney condition should also avoid this vitamin.

Side Effects

Among the possible side effects we have:

  • Chest pains
  • Shortness of breath

Signs of overdose: arrhythmia, loss of appetite, body pain, stiffness and confusion.

Sources of Vitamin D3


  • Tuna
  • Salmon
  • Mackerel
  • Beef liver
  • Egg yolk


  • Mushrooms
  • Soymilk
  • Rice
  • Cereal

This vitamin can be dangerous in excess and should not be ingested in the form of supplements unless a specialist (like a nutritionist) recommends it. If you want to keep yourself healthy and have normal levels of vitamin D3, try expose your skin to the sun with regularity and follow a healthy diet including fish. For regular checkup and appointment bookings you can always contact us.