I have recently received so many questions surrounding vitamin D. Is it really that important? How much should you be taking? What types are best? Is it dangerous if you get too much? Can it harm your thyroid? All great questions.

The answers have a great deal of variation based upon you and your health. Today, I wanted to take some time to dive into vitamin D and what you should know about it. Consider this a primer of everything you need to know about vitamin D.

The Opening Case for Vitamin D

One of the things we know about vitamin D is that it strengthens the immune system.

We also know that those who are low in it are more likely to get ill, catch acute infections, and have additional complications.

And we know that vitamin D reduces the risk of respiratory infections, regulates cytokine production, and limits the risk of other viruses (such as influenza).

But how much is it a marker for good health otherwise?

You are more likely to have good vitamin D levels when you are outside more, when you are active, when you are younger, and healthier. These are all things that also help you have an easier time regulating body weight.

On the other hand, you are more likely to be low in vitamin D when you have a chronic illness, when you are spending more time indoors, and when you are more sedentary.

So, there are debates on how much is important unto itself. We do have good data though.

Coming specifically from medical trials, we know that vitamin D does make a difference. It likely is a marker for other habits, yet it is important on its own, too.1

Vitamin D: Units

An important thing to note here is that vitamin D abides by its own unique units.

One of these are the units most commonly used in medical research and journals. That is what we call nmol/L. The other is the most common unit found in blood tests, called ng/mL.

The conversion between the two is as follows:

  • ng/mL x 2.5 = nmol/L
  • nmol/L / 2.5 = ng/mL

I only say this because I have seen a lot of confusion when it comes to these units. For today’s conversion, I’m going to stick with ng/mL, because that is what you are going to see on your blood tests.

Key Insight: Please know, though, that I have seen many really good discussions around vitamin D, they didn’t realize they were conflating these two units. It is important to know these distinctions and follow recommendations accordingly.

Vitamin D & COVID-19

What we have seen with vitamin D and COVID-19 is a predictive effect of those who are low in vitamin D not only getting ill, but ending up with complications (Click Here: Staying Prepared During COVID-19).

That is because there is good evidence showing that serum levels of vitamin D (related to vitamin D intake) does have dramatic effects on risks of complications due to COVID-19.

It is interesting because, in some ways, this may explain why some groups have more complications than others.

As we discuss more about vitamin D, I will be mentioning how those who are heavier tend to have lower serum levels (which is the amount present in your blood).

That may also be why obesity causes greater risk factors for COVID-19 — potentially because they may have lower vitamin D levels.

And, there are also large differences in skin pigmentation. The more pigmented someone’s skin is, the more apt they are to be low in vitamin D. They are also more at risk for having complications, and even catching COVID-19

Bottom Line:  If you are sufficient in vitamin D, there is less of a likelihood of suffering from complications related to COVID-19.

What Does Sufficiency Look Like?

In terms of ng/mL, sufficiency is defined by around 30-50 ng/mL (this is a bit higher than past suggestions), specifically when it comes to preventing complications.

I have heard many health experts talk about people beginning higher and using nmol/L, and conflating that into ng/mL (another good reason to be conscious of the difference).

Key Insight: Thankfully, there is not a great disparity between the best amount of vitamin D for your health, vitamin D and thyroid health, and your long-term health.

What About Vitamin D and Thyroid Health?

We have good data that those who are low in vitamin D, are at a greater risk for developing and having complications from:

This situation also has a bit of a fascinating wrinkle involved with it.

It seems that adequate thyroid hormones are necessary to maintain vitamin D status. So, if your thyroid hormones are not right, that might be interfering with your vitamin D scores.2

So, was it really that vitamin D caused the thyroid to become abnormal, or was it that thyroid levels caused vitamin D to become abnormal?

We have evidence showing that supplemental vitamin D does have beneficial effects upon thyroid antibodies.

So, even independent of thyroid blood levels, you are more likely to have healthy thyroid antibody levels when you have reasonable vitamin D levels.

This is especially true for antithyroid peroxidase. Many papers have suggested that proper vitamin D levels can lower the risk for improper levels of it.3,4

What About Total Mortality Risk?

You could argue that this is the most important factor to take into account.

What we see here is a distinct C-shaped or J-shaped curve (which you can see below) that when you are really deficient in vitamin D, mortality rates go higher.

But, on the other hand, when there is way too much vitamin D rates also rise in this instance, too. I want to make a key distinct here.

The first is that there is toxicity at play here. There is a place where you are getting so much vitamin D that it is truly doing damage to your body.

Apart from toxicity, though, which is at one extreme, there is a point where above a certain threshold the benefits of vitamin D are no longer apparent.

Key Insight: The benefits of vitamin D plateau around 50 ng/mL, and they even begin to decrease the further you get above that benchmark. Over 70 ng/mL, though, the benefits truly plummet.5

Where Can You Get Vitamin D?

Primarily, your skin makes vitamin D based on sun exposure. You can get it from dietary sources, too. Let’s begin with the dietary sources.

Vitamin D Food Sources

When it comes to dietary sources, there are only a few vitamin D food sources that you are going to find, which include:

The thing is, these are not particularly high amounts here. There simply isn’t enough to make a big enough difference to change your blood levels.

One vitamin D food source that does have higher amounts is cod liver oil. However, it also has a lot of vitamin A, and essential fats. However, it is not something I recommend.

Why is that? Basically, the concern is what we call hypervitaminosis A. This involves getting a toxic amount of vitamin A in your system.

While vitamins may be safer or safeish, they are not harmless.

I consider safety to be a huge priority in my approach, and that really comes down to the fact that there are no do-overs in life. We only get one shot, so we should approach what we do — and what we do to our bodies — with caution and with care.

While you may think you are trying to help your health, and doing all the right things and going above and beyond, you may be unintentionally doing irreparable damage to your system.

It is for that reason that I don’t recommend cod liver oil. The risk is too great when it comes to potentially shortening your lifespan, and I think that matters. It matters to be cautious.

Other Sources of Vitamin D

Beyond food, where else can we get vitamin D? The answer is likely illuminating the world around you right now (unless it’s nighttime). It’s vitamin D from sunlight!

The first thing we have to think about is: how much vitamin D from sunlight are you getting at this moment?

This is especially important to evaluate when we are under quarantine, or sheltering in place.

All of this will be influenced by:

  • Where you live
  • Your skin pigments
  • Skin exposure

Let’s break each of these down to help you understand how much sun you’re getting (and what it all means)…

Sunlight Where You Live

Simply put, this is going to be affected by the latitude of where you live.

Basically, not everyone experiences sunlight the same way. Let me illustrate what I mean with the below chat…

This is what we call the “Sunshine Calendar.” Depending on where you live, and the time of year, you’ll be able to see just how readily you may be able to form vitamin D.

Let’s break it down: imagine that you live, or maybe you do, in the bar that is defined by New York, NY. Across that latitudinal “bar,” in the month of January and February, it’s blank — this means you aren’t going to get sufficient vitamin D from sunlight.

That is just the way of the world and where you live, you simply won’t get enough from the sun shining in the great outdoors.

Then, if you look simply one bar down you’ll have the southern United States. This is where you’ll get vitamin D from the sun all year long, and with larger amounts in the summer.

Bottom Line: Depending on where you live, and the time of year, it is going to greatly affect your ability to garner vitamin D from the sun. You’ll simply have to find other ways to get it, which we will profile later on in this article.

Sunlight and Skin Types

Now, I want to discuss skin types and what that means for your vitamin D absorption.

There is something called the “Fitzpatrick Scale,” which is commonly used in the practice of dermatology. We basically have six different types, which you can see in the image below…

By and large, these are simply differences in the pigmentation of the skin. If we wanted to use an example of people, let’s look at this one…6

The point of the Fitzpatrick Scale is that the melanin, the pigment, is protecting you from vitamin D overdose. So, the more pigment you have, the less vitamin D sunlight is able to provide.

Why would this be a thing? Because, vitamin D is formed at the expensive of a fair amount of free radical exposure to UV light.

You need a lot of free radical formulation to make vitamin D. If you are making vitamin D unchecked, you would make huge amounts of free radicals.

If you are living somewhere like Northern Europe, you’re likely getting too little sun exposure throughout the year.

This ultimately results in very little pigment to block vitamin D formation, because you need that based on where you live!

On the other hand, if you are somewhere like sub-saharan Africa, you have a lot of sun constantly. In that case, if you were making vitamin D all the time you would not be able to function well.

Key Insight: The more pigmented your skin, the more apt you are to be vitamin D deficient.

The sun is really tricky in this way. If you are really fair, you are managing your risk of both vitamin D deficiency and potential skin cancer almost at all times. If you are the opposite, you would need massive amounts of sunlight to keep your vitamin D levels where you need them.

Sunlight Exposure

The next thing to ask is just how much sun you’re getting based on how much time you spend in the sun, and how exposed you are during that time in the sun.

Once you have identified your skin type as per the Fitzpatrick scale, we need to think about how much exposure you are getting. Here’s a helpful image to help you out…7

As you can see, going from left to right can vary dramatically — and, it’s not as likely that we’ll be dressed like the farthest right of the spectrum on a daily basis.

Most people will likely be hovering around somewhere between 16% to 40% based on everyday clothing that we might find ourselves wearing across the globe.

Bottom Line: Sun exposure is incredibly tricky. You are either not getting enough, due to a whole host of factors, or getting too much and putting yourself at risk in other ways.

Body Size & Vitamin D

As we continue to think about the different ways that we “individualize” or tailor our vitamin D needs, we also need to consider our body size and how that plays a role.

What happens here is that body fat, subcutaneous fat especially, stores and sequesters vitamin D. This is based upon the body mass index (BMI), and I want to share this chart to help you self-identify where you may fall on it…

While this scale does have its own limitations, and is not perfect, it can help us predict vitamin D status per intake or percent exposure. This isn’t just sun, but also pills.

Key Insight: The higher your BMI, the more vitamin D you would need to get to the same level.

What we have seen from some papers is that those who have a BMI above 30, their need for vitamin D can be two or three times higher than someone with a lower BMI.

Take a look at this chart for easy reference…

As you can see from the above, someone may need two or even three times as much vitamin D simply based on their body size and nothing more.

What we have also seen is that this is a big part of why a different dose of vitamin D can lead to different blood levels for the same people.8

To get to this ideal point, let’s also look at this chart…

This just shows the variety of needs at play when it comes to vitamin D. Some may need a lot less, and others may need a lot more, to hit their optimal amount.9

Bottom Line: The major takeaway here is that everyone’s needs will differ, and the biggest reasons those shifts are based on body size, pigmentation, and sun exposure, which is why not everyone needs the same amounts.

The Best Vitamin D Supplement For You

Before we really dive into your ideal vitamin D targets, I want to touch on supplementation. Specifically, I want to address the different forms where you can get vitamin D.

The version of vitamin D that is most biologically-active is called vitamin D3. That is the one that has the most consistent effects on benefitting the blood levels — as well as doing all the things that vitamin D seems to do in the body (which is a lot).

We have known for a long time that vitamin D is critical for things like:

  • Bone health
  • Brain health
  • Gut function
  • Immune response
  • Chronic inflammation
  • Chronic pain
  • Tissue regeneration
  • Basal metabolic rate

We now know that vitamin D is working in so many ways, throughout our body, and how crucial it can be to get it in the right amounts.

Key Insight: In that context, D3 is the best vitamin D supplement that you are going to be able to find.

We also know that food sources are not super relevant, and sunshine itself is an imperfect medium, we need to think about supplementation.

What Is Your Best Target For Vitamin D?

Let’s pivot to talking about targets. Now that we understand the importance of supplementation, and how we might want to seek it out, we need to know how much we truly need.

When we talk about targets, we are talking about infectious disease risk, thyroid health, and longevity overall. You don’t want to give up any of these, because they are all important.

Thankfully, your best targets are not going to be that different from one to the next. Really, 30-50 ng/mL is the sweet spot here.

Now, while I wish that was larger, this is a rather exacting target. It is a narrower range that I would like, but that simply is how it has to be.

How Do You Predict Your Vitamin D Needs?

What I typically encourage is having a baseline dosage of vitamin D that is in the context of your multivitamin supplementation. We’ll talk more about that later, but this is a start.

You also need a healthy diet. Supplementation and a good diet are not mutually exclusive — they need to work together and complement one another to really be effective for you.

Key Insight: I would encourage a baseline dosage of 2000 IUs for any adult.

Ultimately, you’ll need more vitamin D if you are:

  • Overweight
  • Obese
  • Fitzpatrick 3 (or higher)
  • Living on a higher latitude
  • Not outside for a half-hour during midday
  • 40% or less skin exposure

Another wrinkle here: stomach function may affect vitamin D absorption. This means that you will want to have vitamin D with a solid meal, and this is especially relevant for anything beyond your baseline dose (where absorption becomes more difficult).

For those who have thyroid disease, this may involve dealing with autoimmune gastritis. This means that they cannot absorb nutrients as well, from supplements, as they may be able to otherwise.

In those cases, the liquid form of vitamin D is typically a great way to go.

Vitamin D and Other Nutrients

So, let’s think about how vitamin D works in the context of other micronutrients.

Let’s use the incredibly-detailed chart below for reference…

It may seem like a lot, but what this chart is illustrating is how vital each nutrient is to your overall immune system (and how your body goes about protecting itself). Every nutrient plays its own role.

If we start by thinking about this collection of nutrients that contribute to the integrity of our immune response it will include:10

  • Vitamin D
  • Vitamin A
  • Vitamin C
  • Vitamin E
  • Vitamin B6
  • Vitamin B12
  • Folate
  • Iron
  • Zinc
  • And More…

It does not mean that you need to take all of those things together, it means you cannot be lacking in any of them.

Think of your nutrients as your body’s physical “barriers” to disease. It helps to keep things from getting in, and in effect keeping you safe from harm.

Bottom Line: The gist of this is that your immune system needs all of your nutrients. There is really not a role where you need only vitamin D — they are all critical and relevant. None of them benefit you in huge amounts, either, it’s all about how they work with one another.

Vitamin D and Bone Health

I love to talk about this because it is critical in understanding how vitamin D works in context, but how it can be bad when things are out of this same context.

So, we think about nutrients that affect bone metabolism. The below chart is one that showcased the different nutrients and how vital they are for bone health…11

First and foremost here was protein. But, as we work our way down we can see the various nutrients and how they interact in various amounts (and not simply more amounts).

Key Insight:  It is always going to be about having these nutrients in the proper spectrum. In my life, this is why I created the Daily Reset Pack.

Action Steps: Vitamin D

So, what should you do when it comes to vitamin D?

As I mentioned, I formulated the Daily Reset Pack with this in mind. This overarching idea that you need to have a full spectrum of nutrients, and that they need to work in concert with one another — including vitamin D — to ensure you’re getting the right amounts.

That includes things like:

  • Vitamin K 450 mcg
  • K1 phytonadione, K2 menaquinone-4, MenaQ7 – MK-6, MK-7, MK-9
  • Zinc 15 mg bisglycinate
  • Manganese – 1 mg bisglycinate
  • Copper – 1 mg bisglycinate
  • Calcium – 350 mg dicalcium malate
  • Magnesium – 300 mg dimagnesium malate
  • Vitamin D3 2000 IU
  • Vitamin C – 400 mg

In here, you get that baseline amount of vitamin D that I mentioned earlier (2000 IU). This is a great starting dose for someone (and then building from there with individual requirements).

Ultimately, you would want to serve the Daily Reset Pack with food.

So, what should you do about that extra vitamin D? I would recommend liquid forms of it, and prefer 1000 IU/drop. This makes it easier to absorb overall.

How do you take it? Simply take the drops, put them right in your mouth, and you can wash them down with water and enjoy them with a meal. They need to go together.

Key Insight: Do not mix in vitamin D with liquids or smoothies. This simply isn’t a good idea, and they need to be taken straight (do not mix them into water).

How Much Vitamin D Should You Start With?

The fact of the matter is that your situation is going to be different.

This is going to be influenced by a whole host of factors, and this does not constitute medical advice at the end of the day.

First, it is important to test your blood levels after 3-6 months to see if you need an adjustment to your dose. But, to help you get started, here is an easy way to think about reasonable starting doses:

Check the box if you:

The starting dose for most adults is 2000 IU. What you will want to do is add one drop of Vitamin D (1000 IU) for each box you checked (If using our Sunny D Vitamin D drops, keep in mind, they are 1000 IU per drop).

For example, if you live in New York, NY, have Fitzpatrick skin type 3, are not outside for an hour per day, have a BMI of 28 and are not known to be low in iron, zinc or B12, you would have checked 4 boxes. You would take your baseline dose of 2000 IU Vitamin D and add 4 drops of Vitamin D to it.

Key Insight: Consider re-testing every 3-12 months, and even try to take advantage of some available home testing that is currently on the market. Your overall goal should be 30-50 ng/mL, and staying within that range is super important for the reasons we detailed today.

A Deep Dive Into Your Health

First, I want to thank you for taking the time to read through our deep dive into vitamin D. I sincerely hope it helped you, and helped add some clarity to the subject.

It is so important that you know you’re getting the right things your body needs, and that you’re getting them in the correct amounts.

If you’re interested in learning more about your body, and your thyroid, please consider taking the Thyroid Quiz (Click Here: Take The Quiz) today.


1 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618598/
2 – https://www.jstage.jst.go.jp/article/endocrj/65/10/65_EJ18-0166/_article
3 – https://sci-hub.tw/https:/doi.org/10.1055/s-0042-123038
4 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618598/
5 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312926/
6 – Image courtesy of laradevganmd.com
7 – Image courtesy of https://www.slideshare.net/Alannmd/clipboards/my-clips
8 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4220998/
9 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4220998/
10 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/figure/nutrients-12-00236-f002/?report=objectonly
11 – Source: Tayel, Dalia & Amine, Ali & Elzawi, Amina. (2013). Dietary Intake of Nutrients Related to Bone Health among Alexandria University Female Students, Egypt. Food and Public Health. 3. 329-335. 10.5923/j.fph.20130306.10.

P.S. Whenever you are ready, here is how I can help you now:

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Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.

Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.