Disclaimer: This is a well-researched article based on scientific sources listed at the end of the article. However, I am not a doctor. Please, always consult with your doctor or local pharmacist before taking Vitamin D supplements.
Hey friends. Let's kickstart this series with one of the most widely discussed Vitamins out there - Vitamin D. Over the past century, Vitamin D. has gained great prominence. But do you know why? Do you know why we need the Vitamin so urgently and why doctors, pharmacists and nutritional experts altogether promote the surveillance and adequate supplementation for a constant proper supply of Vitamin D? Not yet? - Then read on and learn all you need to know about Vitamin D.
The article is structured as follows:
1. What is Vitamin D & Why Do We Need Vitamin D?
2. Vitamin D - That's A Thing For Vegans Only?!
3. Why Can't We Just Absorb Vitamin D From Food?
5. Optional Vitamin D Intake - International Recommendations on Vitamin D intake
6. Vitamin D Rich Foods
7. What Should I Do If I Want To Check My Vitamin D Level?
8. What Is The Best Way To Supplement Vitamin D & How Much Vitamin D Do I Need?
9. Vitamin D3, Vitamin D2 & What Is The Role Of Vitamin K2?
Vitamin D differs from all the other vitamins we know and takes a sort of "special role" in the vitamin category. In fact, if we take a closer look at how Vitamin D functions in our body, we could draw the conclusion that the famous "sun vitamin" should be considered a hormone rather than a vitamin as, in theory, our body should be able to synthesize or "produce" enough Vitamin D by itself if exposed to just the right amount of sunlight every day. However, as many of us don't live in places of the world where they can get "just the perfect" dose of sunlight every day or lead a lifestyle (demanding jobs and inside work, stress, lack of exercise) that doesn't allow for an "adequate sunlight exposure", many of us suffer from Vitamin D deficiency.
Why is this a problem? Vitamin D is very important for proper calcium absorbency, which is one of the main components of our bones. A lack of vitamin D can lead to bone diseases such as osteoporosis, in which the bone loses density, becoming prone to fractures. In growing children, it can be a cause of rickets, a disease that causes stunted growth, weakness and pain of the bones. Other "milder" symptoms of an inadequate Vitamin D supply are increased susceptibility to infections, chronic fatigue, fertility disorders and various forms of depression just to name a few.
Although vegans need to watch their vitamin D consumption closely to make sure they don’t get any health problems, they are not alone. For starters, any person not getting enough sunlight exposure in their daily life, can get Vitamin D deficiency. Though, there are social groups that are affected more than others. Darker-skinned people for example, are prone to this problem, as high concentrations of melanin lower the skin’s ability to make vitamin D from sunlight exposure. Older adults suffer from the same problem, because aging causes the skin to become less capable of producing the vitamin. Breastfed infants do not get enough vitamin D through their mother’s milk, and pediatricians often recommend vitamin D for babies. Lastly, any person with conditions that can affect the absorption of this vitamin, such as diabetes, liver diseases, cystic fibrosis and Chrohn’s disease can suffer from Vitamin D deficiency.
As an interesting side note, according to a study (NVS II) published by the DGE (German Nutrition Society), around 82% of German men and 91% of women (across all social groups; no matter if vegan or not) suffer from a vitamin D deficiency. In addition, the German Robert-Koch-Institut recently published a rounded average of 90% of Germans across all age groups who suffer from Vitamin D deficiency. Causes mentioned were Germany's geographic location (from October to March the sun is not high enough in the sky to supply our skin with the necessary UVB rays UV-index <3), limited storage capacity of Vitamin D, usage of sun blockers, lifestyle choices and the physical state of the individual (age, body weight and skin color).
As mentioned above, Vitamin D differs greatly from all other vitamins with regards to its absorption. On average, only 10-20% of our vitamin D demand can be covered by the food we eat. The remaining 80% should come from our body's own vitamin D synthesis. Hence, our Vitamin D demand, unfortunately, CAN NOT be covered exclusively through food. What therefore matters isn't only the amount of Vitamin D rich foods we include in our diet, but the time we spend in "optimal sunlight exposure" on a daily basis. But watch out, as the storage capacity of vitamin D is limited, too extensive sun baths or "too much sunlight exposure" doesn't help either to fill up our Vitamin D reserves. Instead, it may lead to premature aging of the skin and, in the worst case, skin cancer.
As you can see, finding the "sweet spot for an optimal Vitamin D supply" isn't easy at all and one of the main reasons why doctors, pharmacists and nutritionists altogether recommend to supplement the special Vitamin D. But before we deep dive into Vitamin D supplementation, let's first take a look how much Vitamin D is recommended as an optimal daily Vitamin D supply and the foods that may aid to reach this goal.
Just like with nearly every topic in this world, expert opinions differ. Plus, as so many people around the world are Vitamin D deficient, some experts have a very strong opinion on how to solve the Vitamin D deficiency "pandemic" and take very opinionated stands. For example, there is a big ongoing discussion in Germany whether or not the D-A-CH intake recommendations are too low. Hence, independent expert recommendations started to list alternative "standardized intake recommendations". Both are listed below.
The D-A-CH reference values recommend a daily intake of 800 international units (IE/IU) (also known as cholecalciferol) between the age of 1 and 100 years, including pregnant women and elders. In contrast the alternative reference values recommend 1000 IE/IU between the age of 1-15 years and 2000 IE/IU between 15-18 years as well as 18-65 years. For people older than 65 years, they recommend 4000 IE/IU of vitamin D per day.
Even though Vitamin D differs from all other vitamins trough the natural sun synthesis and demands can't be met exclusively through natural foods, it may help to know which foods naturally contain vitamin D. (I'm talking about these highly unlikely emergency situations in which you are stuck in a grey and cold place without access to sun or Vitamin D supplements ;)). In those cases, you can turn to the following foods:
Vitamin D rich foods are mostly animal based and include egg yolks (218 I.E.), herring fish (1040 I.E.), salmon (680 I.E.), sardines (440 I.E.) and butter (48 I.E.). "Theoretical vegan options" are mushrooms, such as porcini mushrooms (120 I.E.) and Champignons (76 I.E.). The chart below, illustrates the Vitamin D amount of various Vegan- and non-Vegan Foods.
As you can see, non of these options are adequate for meeting our daily needs - especially not the vegan Vitamin D food options - well unless a vegan would start following a pretty crazy died with 1.7-3.4 kg of porcini mushrooms or 2.7-5.4 kg of champignons to cover our daily Vitamin D demand of 2000-4000 I.E. daily. I am pretty sure though that someone following this died would slowly but surely encounter other, undesired side effects and therefore wouldn't recommend any vegan to consider the mushroom diet option for an adequate Vitamin D supply. Sadly, there are currently no other Vitamin D rich vegetables or fruits in the market, so it's important to either rely on the natural sun synthesis or, if this isn't possible fall back on to vitamin D supplements.
As a little sidetone, there have been studies with mushrooms exposed to extensive sunlight which lead to an increased Vitamin D content of the plant and a higher Vitamin D content. Though, these research projects are in "baby stage" and will probably have to wait a few more years until we encounter the first "adequate go-to-market mushroom concepts that aid the management of an adequate vitamin D level.
Generally you can make sure you ingest the right amount of Vitamin D by getting some sunlight exposure every day (not too much! Keep in mind that UV light exposure increases the risk of skin cancer) and a close eye on the intake of vitamin D rich foods. Though, the proper way of making sure your Vitamin D levels are where you want them to be, it’s visiting the doctor’s office and getting your blood analyzed as there are so many factors influencing our natural vitamin D synthesis and an overdose of Vitamin D can also lead to harm our body and lead to severe side effects.
Especially during the cold German winter months I can't recommend it more to pay your doctor or nearby pharmacy a visit and make sure your Vitamin D level is in balance. Not only does it help to prevent long-term bone diseases, adequate Vitamin D supply also prevents infections (colds), counteract fatigue and can have a major impact on our overall mental health and wellbeing.
As a sidetone for all Germans: In Germany you don't even have to visit the doctor. Many pharmacists have educated themselves, offer high-quality consulting and may even be able to make a blood test on site (the pharmacy). I don't know about any other countries. Comment below if you would like to share your experience! :)
If you decide to supplement Vitamin D you can choose between pills and various kinds of liquid Vitamin D supplement options. Personally, I would always recommend to go for a liquid option rather than a pill as liquid Vitamin D options typically come in a oily liquid that supports the Vitamin D absorption. If however, you choose to supplement Vitamin D as a pill, make sure to take it with healthy fats, such as avocado or nuts because it is a fat-soluble vitamin that requires fat for a proper absorption.
Next: What Doses of Vitamin D would I recommend and should I take it all year? Well, since I am not a doctor, I don't want to give you any advices on how much Vitamin D you should take on a daily basis aside from the public recommendations I listed in the chart above. What I can share is my personal intake which is around 2.000-5.000 per day throughout the winter months (October-March). I usually start slow with 1.000 I.E. in the beginning and then increase the amount slowly as the winter days get shorter and darker. And as a tip: What confused me a lot when I started to take with Vitamin D was the secret behind the I.U./I.E. Coding on the Vitamin D label. If, for example, your vitamin D label says 1000 I.E./I.U. this means that one drop contains the equivalent of 1000 I.E.. Therefore, if you'd like to double your dose and take 2000 I.E./I.U., you can just take two drops and your're done. No need to look for a higher-dosed Vitamin D supplement.
And lastly, which brands would I recommend? Well, I'd generally say - any brand with a trustworthy ingredient panel. From personal experience, I can recommend Sunday Natural for example. I truly love their product quality and can recommend it to anyone. However, if you want to purchase local or need immediate access, you can just pay a visit to your local pharmacy and purchase the Vitamin D supplement there.
When purchasing Vitamin D, you can typically choose between Vitamin D3, Vitamin D2 and the combination of Vitamin D with other Vitamins, such as K2.
Vitamin D3 is usually what the doctor would prescribe you as a dietary supplement when the amount of vitamin D in your body is not enough. It’s also the natural form of vitamin D that our bodies make when our skin is exposed to sunlight. However, supplements containing D3 are often (not always) made with the fat of lamb’s wool which makes it an inadequate option for vegans.
The best vitamin D supplement alternative would be Vitamin D2, which comes from mushrooms exposed to sunlight. A study published in 2008 states that this form of the vitamin is as effective as vitamin D3 to meet our daily needs.
We have talked a lot about Vitamin D, but what about Vitamin K2, its essential companion? Articles mentioning Vitamin D and its importance for calcium absorbency often forget to mention Vitamin K2, which intervenes in a crucial step of the task. The way they work together is that Vitamin D enhances the calcium absorption capability of the bone and Vitamin K2 activates the protein that integrates calcium to the bone. On its own, Vitamin K2 is very important, because it helps with blood clotting.
Also, there is a concern, strongly evidence based but not conclusive, that Vitamin D could be harmful without Vitamin K2. It comes from the observation that Vitamin D in high doses promotes calcification of the blood vessels, and Vitamin K can prevent this from happening. Therefore, many companies sell vitamin D supplements as a Vitamin D2 or D3 + K2 "combo-preparation".
I hope you enjoyed this little intro into the world of Vitamin D3. As stated above, there are tons of people out there who suffer from Vitamin D deficiency without being aware. Therefore, feel free to share this post, put in your thoughts and help to spread the word. Because - Sharing is Caring! If you feel like bouncing off your thoughts, get in touch with me through Instagram, Pinterest, Youtube or Facebook. Besides, if you have any feedback for me, questions with regards to the post or if you just want to say "hey", comment below or shoot me a personal message through my contact form.
Love & Plants, Karo
1. Medline Plus (2021): Vitamin D (08.04.2021)
2. Healthline (2020): 6 Great Sources of Vitamin D for Vegetarians (08.04.2021)
3. Research Paper - Meehan/Penckofer (2014): The Role of Vitamin D in Aging Adults (08.04.2021)
4. WebMD (2021): The Truth about Vitamin D and What kind of Vitamin D is best (08.04.2021)
5. Research Paper - Holick et al. (2018): Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D (08.04.2021)
6. Research Paper -van Ballegooijen et al. (2017): The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review (08.04.2021)
7. Healthline (2021): Is Vitamin D harmful without Vitamin K? (08.04.2021)
8. Wissenschaftliche Verlagsgesellschaft Stuttgart (2018): Vitamin D - Die Heilkraft des Sonnenvitamins. 6. Auflage (08.04.2021)
9. Niko Rittenau (2020): Vegan-Klischee ade! Wissenschaftliche Antworten auf kritische Fragen zu veganer Ernährung. 7. Auflage 2020 (08.04.2021)
Note: The advertisement of Sunday Natural products in this article is UNPAID.