Vitamin D2, vitamin D3 or just vitamin D? In everyday life, people often only talk about vitamin D. But what is the difference between vitamin D and vitamin D3? We will get to the bottom of this question in this article and provide answers to the most important questions on the subject.
In addition to essential background information about vitamin D and its subgroups, we have also dealt with the four most important differences between vitamin D and vitamin D3. We want to ensure that you are informed in detail about the topic and finally get clarity. Have fun while reading!
the essentials in brief
- Strictly speaking, vitamin D is not a vitamin, but a hormone that the body mainly needs to strengthen the bones.
- It can exist in two forms, vitamin D2 and vitamin D3. While vitamin D2 is only absorbed through food and supplements, vitamin D3 can also be produced through exposure to the sun on the skin.
- Compared to other vitamin D groups, vitamin D3 proves to be the most effective form and helps the body to increase vitamin D levels as best as possible.
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Definition: What is vitamin D?
Because vitamin D has the word vitamin in its name, many people understandably assume it is a vitamin. Strictly speaking, however, this is not the case, as one can speak of a hormone rather than a vitamin.
Because vitamins are organic compounds that the body cannot produce itself, or only to a small extent, but urgently needs to survive. In order to be able to produce these vital compounds, vitamins must be ingested through food.
The vitamin D mentioned, on the other hand, cannot only be supplied to the body through food like other vitamins, but also through other methods such as sufficient sunlight, which stimulates the body to produce vitamin D. In addition, vitamin D is also often supplemented (1).
Vitamin D is primarily used in the body to strengthen bones. Good vitamin D levels can prevent serious falls and fractures. (Image sources: Dariusz Czapski / unsplash)
Vitamin D is primarily needed in the body to support bone metabolism. This is made possible by the positive effects of vitamin D on the absorption of calcium and phosphate (2). The two main forms in which vitamin D can occur are vitamin D2 and vitamin D3, both of which are also known as calciferols.
What is vitamin D2?
Vitamin D2, also known as ergocalciferol, is a vitamin D group that can be found primarily in plant foods. Said plants can ideally use daylight to trigger a photochemical reaction that leads to the formation of vitamin D2.
After ingestion through food, vitamin D2 is transported to the liver where it is converted to calcidiol. It is then sent to the kidneys where calcitriol is produced. This is needed to supply the bones with calcium and to support the intestines in absorbing calcium and phosphate (1).
Since vitamin D2 is only found in plant products such as mushrooms, this source of vitamin D is particularly suitable for vegans and vegetarians. In addition, vitamin D2 can also be ingested through supplements.
At this point, however, it must be mentioned that vitamin D2 preparations are hardly used in Europe. However, the picture is different in the US, where vitamin D2 is commonly administered to patients.
The fact that vitamin D2 is used less frequently than vitamin D3 in Europe may be due to the fact that vitamin D3 is considered to be the more effective vitamin D group. Because if you want to achieve the same effects with vitamin D2, vitamin D2 must be administered in significantly higher doses (3).
What is vitamin D3?
Unlike vitamin D2, vitamin D3, also known as cholecalciferol, can only be found in animal products. The foods that contain the most vitamin D include deep-sea fish, dairy products and offal. Just like vitamin D2, vitamin D3 is also used primarily by the liver and kidneys to produce the hormone calcitriol (1).
But vitamin D3 can not only be absorbed well through food, but also through direct sunlight. In winter, however, this is only possible to a limited extent due to the short hours of sunshine and the weak rays of the sun.
A visit to the solarium can remedy this, but caution is advised, as the intensity of the rays can also be too strong and this can increase the risk of developing skin cancer (4).
As already mentioned, vitamin D3 is mainly used in Europe because it has proven to be more effective than vitamin D2. Vitamin D3 tends to increase the vitamin D value in the blood more than vitamin D2, sometimes even doubling it. Thus, no equivalence can be ascribed to the two forms with regard to their effect (5.6).
Background: What you should know about vitamin D and vitamin D3
Before we present you with the specific differences between vitamin D and vitamin D3, we have summarized the most important background information on the subject in the following sections.
Why does the body need vitamin D and vitamin D3?
As previously mentioned, vitamin D is needed to strengthen bones, which is facilitated by improved absorption of calcium and phosphate in the gut. Vitamin D is therefore used to make the bones harder and therefore more stable (2).
Furthermore, vitamin D is also said to have positive effects on the immune system and the inhibition of diseases. Since vitamin D contributes to the formation of new T cells, which are needed to fight off disease, the immune system can be sustainably strengthened (7).
In this table you will find a brief overview of the influence of vitamin D on different diseases:
| Illness | Effect |
|---|---|
| depressions | Vitamin D stimulates the production of the happiness hormone serotonin. The lower the serotonin, the more prone you are to depressive moods. Vitamin D therefore has a positive effect on mood and helps to alleviate signs of depression (8). |
| Cancer | Vitamin D also has an impact on cancer risk when combined with calcium. This combination may lower the risk of developing cancer (9). |
| cardiovascular diseases | Adequate vitamin D levels can prevent HDL concentrations in the blood from falling and, as a result, increase the risk of cardiovascular disease (10). |
| asthma | It has been found that lung function worsens in people who have very low levels of vitamin D, as does the glucocorticoid response. At the same time, there is increased airway hyperreactivity. Vitamin D can help improve these levels, treat asthma, and slow the progression of the disease (11). |
| type 2 diabetes | One study found that low levels of vitamin D could be associated with worse insulin resistance. As a result, type 2 diabetes can easily be triggered (12). |
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How much vitamin D and D3 does the body need?
The need for vitamin D can vary from person to person. However, the International Osteoporosis Foundation (IOF) has published some guidelines based on the Institute of Medicine (IOM) on its website (13). At the same time, however, it is pointed out that there is no optimal and universal value.
Ideally, the vitamin D level should be around 70-80 nmol/l (13).
Older people are particularly prone to vitamin D deficiency because they spend a lot of time at home and little exposure to the sun when their mobility is restricted. In order to achieve the ideal vitamin D level of 70-80 nmol/l, the IOF recommends a dose of 800-1000 IU per day for these people (13).
Looking at the guidelines for the other age groups shows that infants under one year old should consume around 400 IU per day, while people aged 1-60 years are recommended to take around 600 IU of vitamin D per day (13).
Vitamin D can either be ingested through food or, in the case of vitamin D3, through exposure to the sun. In addition, there is the possibility of using dietary supplements. However, these should be clarified with a doctor.
What happens with a vitamin D or vitamin D3 deficiency?
While a blood concentration of 50 nmol/l or more is a good vitamin D value, a concentration below 30 nmol/l is considered too low. In this case, one also speaks of a vitamin D deficiency (4). Contrary to all assumptions, however, poor vitamin D levels are not uncommon.
People who spend little time outside their own four walls and who cover a large part of their skin are particularly affected. In addition, the color of the skin also plays a role, since vitamin D can be formed more easily on lighter skin than on darker skin. In addition to people who spend a lot of time at home, infants can also be assigned to the risk group because they should be protected from the sun (4).
The consequences of a vitamin D deficiency can manifest themselves in different ways.
In young people, such as infants and children, not enough vitamin D can prevent bones from being strengthened. As a result, they remain soft and can also be easily deformed. In this context one speaks of a so-called rickets (14).
The consequences of vitamin D deficiency can also be seen in adults. Since the bones are not sufficiently mineralized, they can become soft again, which is also known as osteomalacia. In addition, a disorder of the bone metabolism is also often found. A direct consequence can be osteoporosis, especially in older people (14).
How can vitamin D and vitamin D3 be absorbed?
Vitamin D can be absorbed in different ways. While vitamin D2 is primarily ingested through plant foods that have been exposed to sunlight, vitamin D3 is only found in animal products. In addition, vitamin D3 can be absorbed transdermally through the skin with the help of direct sunlight.
How much vitamin D actually gets into the body is determined by several factors. These include, for example, the geographical location, the season, the position of the sun and clothing.
In addition to food and sunlight, there are also tablets and drops as well as oils and creams that can help with vitamin D absorption. How well which method works also depends on the type of person. However, supplementation can also have side effects, so caution is warranted (16).
Should you supplement vitamin D and D3?
Basically, the vitamin D level is highest between March and October, since a lot of vitamin D can be absorbed from the sun at this time. In the winter months, on the other hand, the body falls back on vitamin D stores in which it has built up reserves over the course of the year. These are found in fat and muscle tissue (17).
In order to absorb vitamin D, natural methods such as food and sunlight should be used whenever possible. If you still have low vitamin D levels despite taking vitamin D from the sun and food, you can also use oral and transdermal supplements.
At the same time, however, it is important to note that there are a number of factors that determine how well vitamin D is absorbed. In addition to body weight, movement, skin pigmentation, age and genetic predisposition also play an important role. Furthermore, the dosage and the vitamin D group used for supplementation must also be considered (16).
What happens with a vitamin D or vitamin D3 overdose?
As already mentioned, a vitamin D deficiency can have serious consequences for the body. However, the situation is similar at the other extreme, namely vitamin D overdose. This can easily lead to vitamin D poisoning (intoxication).
Intoxication can be caused by different factors. Probably the most common cause of vitamin D poisoning is too long or too much intake of vitamin D via supplements. In addition, a malfunctioning metabolism can also lead to vitamin D intoxication (18).
Too high a vitamin D level leads to a calcium overdose, also known as hypercalcemia. The direct consequences include dizziness, disorientation, nausea and vomiting, abdominal cramps, and severe thirst and dehydration. However, the intoxication can also take a much more severe course and cause kidney damage or even death (18).
What is the difference between vitamin D and vitamin D3?
If you inform yourself about vitamin D, you will notice that vitamin D and vitamin D3 are often used interchangeably. Since vitamin D3 and not vitamin D2 is used almost exclusively in Europe, vitamin D3 is actually often meant. Nevertheless, a distinction should be made between the two terms.
The differences between vitamin D, especially vitamin D2, and vitamin D3 manifest themselves on different levels. In order to bring them a little closer to you, we have worked out and briefly summarized them in the following sections.
Difference 1: food
The production of vitamin D3 is primarily stimulated by the sun's rays on the skin. Furthermore, vitamin D3 can also be ingested through food. Vitamin D3 can mainly be found in animal products.
The foods (19) that contain the most vitamin D3 include:
- Fatty fish such as salmon, mackerel or herring
- Egg yolk
- Meat
- offal such as liver and kidneys
In addition, there is also vitamin D3, which is obtained from plants, including certain types of lichen. Therefore, vitamin D3 is also available in vegan form (19).
Vitamin D, on the other hand, can be obtained from both animal and plant products because it can consist of several vitamin D groups. As already described, these include either vitamin D3 or vitamin D2, which comes purely from plant production. Leading the way are mushrooms, which grow in the wild and enjoy plenty of sunlight (19).
In addition, there are also some foods that are fortified with vitamin D2 or D3. This primarily includes dairy products such as yoghurt, milk and margarine, but muesli or juices can also contain vitamin D. These products are primarily available in the US and UK (19).
In the following table we have summarized the most important products and their vitamin D values:
| product | Vitamin D values per 100 grams |
|---|---|
| herring | ≈ 31 micrograms |
| Salmon | ≈ 16 micrograms |
| oysters | ≈ 8 micrograms |
| smoked eel | ≈ 90 micrograms |
| cod liver oil | ≈ 300 micrograms |
| beef liver | ≈ 1.7 micrograms |
| chicken liver | ≈ 1.3 micrograms |
| Gouda cheese | ≈ 1.3 micrograms |
| porcini mushrooms | ≈ 3.1 micrograms |
| mushrooms | ≈ 1.9 micrograms |
Difference 2: recording
But the intake of vitamin D can also look different. One way is to get vitamin D through food. Because, as already described above, small doses of vitamin D2 and vitamin D3 are found in certain foods.
In the case of vitamin D3, however, there is another possibility, namely vitamin D formation through exposure to the sun on the skin. In this context, the 7-dehydrocholesterol present in one of the layers of the skin plays a major role.
When the skin is exposed to sufficient sunlight, the 7-dehydrocholesterol is converted into cholecalciferol, i.e. vitamin D3, via photolysis and absorbed into the body (20,21).
In order to absorb enough vitamin D, 15-30 minutes in the sun is often enough. However, you should be careful not to get sunburned or apply too much sunscreen, as this can inhibit vitamin D absorption. (Image sources: Herbert Goetsch / unsplash)
In contrast to other forms of vitamin D, vitamin D3 can therefore be absorbed through sunlight or food and supplements. However, other vitamin D groups such as vitamin D2 can only be supplied through food or supplements. How vitamin D is absorbed is therefore strongly related to the respective vitamin D group.
Difference 3: conversion
If you take a closer look at the conversion of the vitamin groups in the body, you will notice that these can vary greatly. Compared to vitamin D2, vitamin D3 can be transported more easily and quickly through the blood. This is due to the fact that vitamin D3 has better binding in terms of transport molecules. Thus, vitamin D3 is also better metabolized than other forms of vitamin D (22).
Furthermore, vitamin D in the form of vitamin D2 is said to have a less lasting effect than vitamin D3. In contrast to vitamin D2, vitamin D3 keeps the blood levels high and thus ensures that the vitamin D3 can work for a long time.(23)
A closer look at the liver, where both vitamin D groups are processed and converted, shows that the organ is more responsive to vitamin D3. The enzymes responsible for converting vitamins D2 and D3 into vitamin D convert vitamin D3 more easily than other forms of vitamin D such as vitamin D2 (24).
Difference 4: Effectiveness
There is a lot of discussion and research going on, especially with regard to the effectiveness of the different vitamin D groups. In the course of a study, it was found that the 25(OH)D values, i.e. the calcidiol values, can be increased more with vitamin D3 than with vitamin D2, which means that the two vitamin D groups are not of equal value (25) .
Vitamin D3 is significantly more effective in the body than other vitamin D groups (22).
A study by the British University of Surrey came to a similar conclusion. It was shown that a test group that had taken vitamin D3 was able to achieve a significantly higher increase in vitamin D levels than the group that had received vitamin D2.
Furthermore, the vitamin D levels in the blood of the vitamin D2 subjects were only half those of the vitamin D3 group (26).
The higher effectiveness is probably related to the fact that vitamin D3 is easily absorbed and transported into the blood. Furthermore, vitamin D3 can last longer than other vitamin D groups because it is not eliminated as quickly (22).
Conclusion
So is vitamin D3 the same as vitamin D? no Although vitamin D3 is vitamin D, it is only a subgroup of the hormone. Since vitamin D can also be formed from vitamin D2, not every vitamin D is automatically and exclusively vitamin D3. Therefore, care should be taken when using the terms synonymously.
As has been shown, there are significant differences between vitamin D3 and vitamin D. While vitamin D from subgroups such as vitamin D2 can only be ingested through food and supplements, vitamin D3 is also formed on the skin through exposure to the sun. Furthermore, the vitamin D level in the body can be increased very quickly and effectively with the help of vitamin D3.
Individual proofs(26)
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- Khazai N, Judd SE, Tangpricha V. Calcium and vitamin D: skeletal and extraskeletal health. Curr Rheumatol Rep. 2008;10(2):110-117. doi:10.1007/s11926-008-0020-y Source
- Glendenning, Paul, et al. "Calculated Free and Bioavailable Vitamin D Metabolite Concentrations in Vitamin D-deficient Hip Fracture Patients After Supplementation With Cholecalciferol and Ergocalciferol." Bone, vol. 56, no. 2, 2013, pp. 271-5. Source
- Selected questions and answers about vitamin D Common FAQ of the BfR, the DGE and the MRI from October 22, 2012 Source
- HM Trang, DE Cole, LA Rubin, A Pierratos, S Siu, R Vieth, Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2, The American Journal of Clinical Nutrition, Volume 68, Issue 4, October 1998 , Pages 854-858, https://doi.org/10.1093/ajcn/68.4.854Source
- Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012;95(6):1357-1364. doi:10.3945/ ajcn.111.031070Source
- Konijeti GG, Arora P, Boylan MR, et al. Vitamin D Supplementation Modulates T Cell-Mediated Immunity in Humans: Results from a Randomized Control Trial. J Clin Endocrinol Metab. 2016;101(2):533-538. doi:10.1210/jc.2015-3599 Source
- Khoraminya N, Tehrani-Doost M, Jazayeri S, Hosseini A, Djazayery A. Therapeutic effects of vitamin D as adjunctive therapy to fluoxetine in patients with major depressive disorder. Aust NZJ Psychiatry. 2013;47(3):271-275. doi:10.1177/0004867412465022 Source
- Joan M Lappe, Dianne Travers-Gustafson, K Michael Davies, Robert R Recker, Robert P Heaney, Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial, The American Journal of Clinical Nutrition, Volume 85, Issue 6, June 2007, Pages 1586-1591, https://doi.org/10.1093/ajcn/85.6.1586Source
- Maki KC, Rubin MR, Wong LG, et al. Serum 25-hydroxyvitamin D is independently associated with high-density lipoprotein cholesterol and the metabolic syndrome in men and women. J Clin Lipidol. 2009;3(4):289-296. doi:10.1016/j.jacl.2009.07.003 Source
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- Vitamin D, IOF International Osteoporosis Foundation Source
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