In Articles +tips/ Nutrition

Should you take vitamin D3 or D2? Which one is better?

As a nutritionist, I often recommend supplements to clients when necessary. I am all for getting vitamins and minerals from your diet, but in some cases, a supplement is vital. There’s no other way out.

One such supplement is vitamin D. It’s hard to get enough vitamin D from the diet and if you live in a country with limited sunshine (especially in the winter), you could be vitamin D deficient [1]. So your best bet is to take a supplement.

There are different kinds of supplements available and one question I get asked is:

Should I take vitamin D2 or vitamin D3? Which is bettter?

Years ago, the answer would have been “it doesn’t matter”. It was thought that vitamin D2 and vitamin D3 were interchangeable and the type of supplement you took made no difference. But is that really the case?

Let’s dig a little deeper.



Before we begin, let’s do a short vitamin D 101.

What is vitamin D?

Vitamin D is a fat soluble vitamin that is essential for good health, especially for bone health.  It’s one of the few vitamins that the body can make itself, so we don’t need to rely completely on our diet to get enough vitamin D. Given that very few foods (e.g eggs and fatty fish) have vitamin D, it’s a good thing that our bodies can make it.

How does the body make vitamin D? When sunlight hits your skin, a substance in your skin called 7-dehydrocholesterol turns into vitamin D3, which is carried to your liver and then your kidneys to transform it to active vitamin D.

Now if you live in a place like Canada which there is not enough sunlight exposure for most of the year, you could have low vitamin D levels. What does that mean for your health?

Why do we need vitamin D?

Vitamin D is required for a number of functions in the body. We may think it’s mainly for bone health, but that is not the case. It’s so much more than that!

  • Bone health
  • Immunity
  • Muscle function
  • Cardiovascular health
  • Anti-cancer effects
  • Respiratory health

Should I take a supplement?

If you get adequate sun exposure throughout the year (e.g. if you live in a warm place close to the equator) and have been tested to have good vitamin D levels, you probably don’t need a supplement.  Talk to your health care professional to help you make the best decision.

Now if you live in a climate which doesn’t allow for year-round sun exposure, you might have low level of vitamin D. Ideally, you should ask your family doctor to get your vitamin D levels tested so you can get a clearer picture. That way you’ll know exactly how much you need to supplement with.

What if your doctor refuses to get the test done? Tough call, but there’s no harm in taking a daily supplement to be on the safe side, especially if sun exposure is limited. The current recommended daily allowance is 600-800 IU per day for adults [2]. But there is ongoing research stating that the current RDA is on the lower side and we actually need more [3,4,5].

I personally take 2000 IU per day in the summer and 3000 IU per day in the winter. This because I have limited sunlight exposure throughout most of the year. I also have darker skin, which means my body can’t produce as much vitamin D when exposed to sunlight as person with fairer skin.

I leave it up to you to decide what works best for you.

Just remember that the upper tolerable limit is 4000 IU per day [6], so if you plan on taking more than 4000 IU a day, definitely speak to a health care professional about getting your vitamin D levels monitored.

What are the different kinds of vitamin D supplements?

At your local pharmacy, you’ll most commonly see vitamin D2 and vitamin D3 supplements.

Vitamin D2 is called ergocalciferol and is made by irradiating plant matter with UV rays. Vitamin D3, known as cholecalciferol is typically made by irradiating lanolin from sheep’s wool with UV rays [7].

Note: Given the method of production, vitamin D2 is more suitable for vegans who choose not to include any products made from animals. Just to be clear, the flesh of the animals is not typically used in vitamin D3 production, so vitamin D3 made from lanolin is still suitable for vegetarians (but not for vegans).

Between vitamin D2 and vitamin D3, which one is more effective?

Let me share my personal story before we delve further.

In late 2011, I went back home on vacation and met with one of my dad’s friends who happens to be an orthopedic specialist. He recommended that both my husband and I should take vitamin D supplements because we live in Canada and aren’t getting enough sun exposure. He prescribed a three-week mega-dose of vitamin D2 which both of us took diligently. I also maintained my daily intake of milk at about 3 cups a day in order to get enough vitamin D. Six months later, I got a blood test done, hoping my levels would be normal. Were they? No way!

In spite of taking a mega-dose supplement and drinking so much milk, my vitamin D levels were dismally low (18 ng/mL)! The same for my hubby. It made no difference to the two of us.

Vitamin D2 didn’t work for us, but what does the research say about it?

Recent research shows that vitamin D3 is MORE EFFECTIVE than vitamin D2 in increasing and maintaining vitamin D levels in the body. That probably explains why vitamin D2 was not that effective for us.

  • A review from November 2011 [8] stated that vitamin D3 reduced mortality in adults, while other forms of vitamin D did not.
  • Another study from 2010 [9] stated that D3 is approximately 87% more potent in raising and maintaining vitamin D levels.  They even went on to conclude:

Given its greater potency and lower cost, D3 should be the preferred treatment option when correcting vitamin D deficiency.

  • In a study from 2013 [10], researchers found that daily supplementation of vitamin D3 over the winter months was more effective than D2.

I’ve just highlighted a few studies here, but there are countless studies that show evidence that vitamin D3 is more effective [11,12,13,14]. As with anything, you’re bound to find a study or two that has different results, such as this one [15].

But the vast majority of studies on this matter, as well as this meta-analysis of several studies [16], confirm that vitamin D3 is a better choice.

Bottom line?

If you’re thinking of supplementing with vitamin D, go for vitamin D3 as it’s more potent. If you’re vegan, go with vitamin D2, but do speak to your doctor about getting your levels tested regularly so you can up the dose if required.

Do you take vitamin D? What has your experience been? Leave us a comment below!

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