Vitamin D vs D3

Vitamin D is commonly known as the ‘sunshine vitamin’. It is one of the nutrients that is gathering a lot of attention from scientists recently, and various studies have now shown that it is incredibly beneficial for mood, immune health and controlling blood sugar levels. As a result, vitamin D supplements are now some of the most popular on the market. However, many don’t quite understand what it is, and they certainly don’t know that it is actually a group of vitamins.

Having a vitamin D deficiency, which can be caused by a variety of factors, is a real health issue. Yet it now seems that around 50% of people in the developed world suffer from it. If you were to look into this, however, you would be forgiven for becoming confused, not in the least because there are two kinds of vitamin D: D2 and D3. Let’s try to shed some light.

All About the D Group of Vitamins

Vitamin D2 is the type of vitamin D that is found in cereals, juices, milks and other fortified foods. D3, by contrast, is the vitamin that the skin synthesizes through sun (or UV light/UVB) exposure. D2’s medical name is ‘ergocalciferol’ and it naturally occurs in a number of fungi and plants. D3’s medical name is cholecalciferol, which is produced with the help of sunlight but it can also be manufactured by some animals. Because D3 is naturally produced by the body, D3 is more like a hormone than a vitamin. D2 and D3, together, regulate the levels of phosphorus and calcium in the body. They do this by converting into calcitriol, which is a hormone.

The debate is on which one of the two is most effective, with many saying D3 is better. This is because just 10 to 15 minutes of sun exposure, three to four times a week is enough, so long as you don’t wear sunscreen. If you cannot achieve this, then it is recommended to take a supplement. The recommended levels are 1,000 IUs for anyone over 20. The supplements are usually created using lamb wool fat.

At the same time, however, a 2008 clinical study showed that D2 is equally effective. D2 is what is found in many supplements and it is gained from irradiated fungus. D2 is also often found in prescription medication, because it is very potent. This is also why it is important to tell a physician if you are taking supplements, as you may not need them.

What Is Vitamin D2?

Certain plants produce vitamin D2 as a response to the rays of the sun. This is most strongly found in certain mushrooms. When these are irradiated, their nutrient content increases. The vitamin is often added to fortified foods in order to improve its nutrient quantity. This is particularly important for those who follow a dairy-free diet.

What Is Vitamin D3?

When the skin is exposed to the sun, it converts UVB rays into pre-vitamin D-3, which then goes to the liver. The liver transforms it into calcidiol and proteins then carry this to the kidney, where it is turned into calcitriol. The more sunlight you are exposed to, the more calcitriol you will be able to have. Wearing an SPF factor 8 sunscreen lowers the body’s ability to produce calcitriol by as much as 95%.

D3 is the most active biological form of vitamin D. It is vital to have sufficient levels of this in order for the bones to absorb calcium. Scientists uncovered this when they found that cod liver oil helped to prevent rickets, a bone weakening disease common in children towards the end of the 19th century, as they were not exposed to sunlight due to living and working conditions.

What Is It For?

If you do not have sufficient levels of vitamin D, no amount of calcium could keep your bones strong, because calcium can only be absorbed with the assistance of vitamin D. Furthermore, this vitamin regulates how cells grow, including those responsible for killing bacteria and for the immune system. There is now also some research to suggest that vitamin D can lower blood pressure and prevent certain types of cancer.

Vitamin D Is Synonymous with Health

In almost all studies that have looked into vitamin D, the results have been virtually the same: vitamin D3 is what our body needs in order to be healthy. There is a lot of evidence to show that the body finds it easier to absorb D3 compared to D2. In fact, it is approximately 300% more effective than vitamin D2. Additionally, it is better at reducing death rates overall and it helps to maintain the overall vitamin D levels, which is important during darker, winter months.

Sources of Vitamin D

There are just a few sources of vitamin D. Interestingly, most of these sources are avoided by people, albeit unintentionally. By knowing the sources, you can naturally increase your levels of vitamin D.

There are just a few sources of vitamin D. Interestingly, most of these sources are avoided by people, albeit unintentionally. By knowing the sources, you can naturally increase your levels of vitamin D.

Source  Effect
Sunlight Simply exposing your skin to the sun each day is a great way to increase your levels of vitamin D. This is not because the rays of the sun contain the vitamin, but rather that it helps the body to synthesize it. This is the most natural way to increase levels of the vitamin. Unfortunately, because we spend most of our days inside now, most people no longer have sufficient sun exposure.
Food A number of both natural and processed foods contain vitamin D. However, people often find that there is not enough variety in these foods, and that they can also be difficult to access. This is particularly true for vegetarians and vegans, as many of the sources of vitamin D are animal based.

Fortified sources include:

·         Cereals

·         Cow’s milk

·         Certain grain products
Whole foods that include vitamin D naturally include:


·         Egg yolk

·         Fish

·         Pork

·         Fermented soy


This clearly shows that vegans will find it very difficult to get vitamin D from natural sources. Additionally, non-organic fortified food types often include a range of pesticides, preservatives and additives that can lower vitamin D levels, and there is some suggestion that genetically modified food also has lower levels of vitamin D. Hence, it is vital to always choose organic foods.


Only a few food sources contain natural levels of vitamin D. This is why most milk is now fortified with extra vitamin D, and many other dairy products are also enriched. However, this is not a legal requirement, so make sure you read the label if you want to find out whether you are getting enough units of vitamin D.

Supplements By far the best way to make sure you get sufficient vitamin D is to supplement your diet. This is a really easy way to make sure that you have enough levels. It is recommended to choose a vitamin D3 supplement and not vitamin D2. Vegans and vegetarians must check whether the supplement is suitable for them.

Vitamin D vs. Vitamin D3 – A Comparison

1. Vitamin D3 is more natural, as it is created in our body. Vitamin D2 is not naturally produced by our body.
2. There is no difference in cost between the two vitamins.
3. There is a suggestion that D3 is less toxic than D2. This is because we consume quite a lot of D2 through other products.
4. D3 binds to human tissue receptors better than D2.
5. D3 is highly potent, which can make it more beneficial.
6. D3 has a more stable shelf life, meaning it will stay active for long regardless of environmental factors.
7. D3 has been most commonly tested in clinical trials, so more is known about it.
8. D3 helps not just to raise but also to maintain levels in the blood because it circulates properly in the body.

The Bottom Line

While there has been one study that showed D2 was as effective as D3, this study has not been replicated yet and is therefore inconclusive. By comparison, there is a lot of data available about the effectiveness of vitamin D3 and how it can benefit the entire body. Vitamin D3, therefore, is the necessary nutrient for the human body. Take a look at your daily food consumption and sunlight exposure to work out whether or not you get sufficient vitamin D in your body, or whether you may need to supplement.

Resource and References:

Dietary Reference Intakes for Calcium and Vitamin D – Diet sources of calcium and vitamin D. (National Academies Press)
Vitamin D Regulation of Immune Function – How vitamin D regulates the immune system. (
Vitamin D Supplementation for Prevention of Mortality in Adults – Relationship between vitamin D and mortality. (
Vitamin D(3) Is More Potent than Vitamin D(2) in Humans – Potency of vitamins D2 and D3. (
Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans – Comparison of Vitamins D2 and D3. (Endocrine Society)
Vitamin D Supports Healthy Blood Sugar – Effect of vitamin D on blood sugar level. (Life Extension Magazine)