The Sunday Leader

Good advice from Dr. Harold

Difference between vitamin D2 and D3

I was asked, “What is the difference between vitamin D2 and D3?”

Vitamin D3 is produced in your skin from cholesterol (7-dehydrocholesterol) triggered due to exposure to the UVB radiation from the sun. But unfortunately, Sri Lankans even in Sri Lanka may not get sufficient vitamin D3, being a tropical country with full day sunshine, because they are indoors at home and at workplace, travel in air-conditioned vehicles, and always attempts to avoid the direct sun. Traditionally, Sri Lankans don’t seem to wear hats.

You need at least half hour exposure to direct UVB rays of the sun for pigmented people and twenty minutes exposure for light skin individuals. Light skin people could get sunburnt if over-exposed and becomes a major risk factor for skin cancer. The alternative is to take vitamin D capsules as a supplement.

This ‘sunshine’ vitamin comes in two forms: Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol).

Now, you want to know the difference?

-          Both are fat soluble and needs to take foods with fats.

-          Vitamin D3 comes from animals and D2 from plants.

-          Animal sources are oily fish, liver, egg yolk, butter and dietary supplements.

-          Vitamin D2 is found in plant sources, like mushroom, fortified foods and dietary supplements.

Both D2 and D3 supplements and foods are absorbed into the bloodstream through your gut quite efficiently. The liver seems to metabolise the two differently.

Bit technical now: Vitamin D2 is broken down into 25-hydroxyvitamin D2, and vitamin D3 into 25-hydroxyvitamin D3. They are collectively referred to as calcifediol.

It is calcifediol that circulates in your blood, and on routine blood test for vitamin D level, it is the cacifediol level that is estimated.

It is observed that Vitamin D2 seems to produce less calcifediol, and vitamin D3 seems to raise the level more.

So, when you buy vitamin D from your pharmacist check that you are buying D3 and not D2.

You need to check your blood vitamin D level annually. Deficiency can cause problems without your knowing.

Vitamin D also functions as a steroid hormone which helps you to avoid erectile deficiency for men. This vitamin as a steroid hormone gets into the nuclei of every cell in your body to activate gene function, or switch off.

It is also revealed that deficiency can activate cancer development at cellular level.

It is observed that deficiency in vitamin D can lead to increased risk factor for heart disease.

Children need to be fed with adequate amounts of vitamin D to avoid Type 1 Diabetes. Type 1 diabetes is caused due to your body immune system destroying the cells in the pancreas that produces insulin. Children should be given 2,000 IU per day to lower the risk of developing type 1 diabetes.

Adults also need to take vitamin D supplements to avoid developing diabetes. Adults need to take these supplements to avoid falls and fractures of bones among the elderly. They should take at least 800 IU per day.

Children and adults suffering from asthma and frequent attacks of flu need to take vitamin D daily. It is shown that taking vitamin D supplements reduces the risk of respiratory infections and other diseases affecting the bronchial tubes and lung tissue.

Taking vitamin D supplements also extends your life span and reduces total mortality by over 6 per cent.


Get your vitamin D level in your blood checked annually and take remedial measures, if required.

Hope this article is useful. (Some reference to the article on Healthline)

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