Why Care About Vitamin D Deficiency?

Why Care About Vitamin D Deficiency? https://www.thorne.com/products/dp/d-10-000

Updated from original post dated: September 30, 2014

Why has Vitamin D Deficiency been in the news and all over the web lately, and why should you care? For starters, according to a recent study published in the journal Nature, “Vitamin D deficiency markedly increases the chance of having severe disease after infection with SARS Cov-2 [COVID-19]. The intensity of inflammatory response is also higher in vitamin D deficient COVID-19 patients. This all translates to increase morbidity and mortality in COVID-19 patients who are deficient in vitamin D.”(1)(2) No bueno!

And that’s just the most current tip of the iceberg when it comes to vitamin D deficiency. Besides rickets, vitamin D deficiency has also been implicated in a wide variety of ailments ranging from enhanced intestinal permeability (a.k.a. Leaky Gut), osteopenia, and osteoporosis, to autoimmune conditions, Parkinson’s, and cancer. So as you can see, vitamin D is a VERY important nutrient.

So could you have Vitamin D Deficiency? How can you find out? And how can you safely supplement if you’re deficient? Let’s find out…

What is Vitamin D?

Vitamin D deficiency was first discovered in 1920 as a cause of rickets. And at that time “vitamin D” was originally thought to be a vitamin. According to more recent research cited by Dr. Perlmutter in the Grain Brain, “Vitamin D is actually a critically important fat-soluble antioxidant that acts like a steroid or a hormone in the brain.”(4) In fact, if it were discovered today scientists say it would be called a ‘pre-hormone’ not a vitamin, as it interacts with all of our other hormones and is not actually a ‘vitamin’ at all.

Why is Vitamin D So Important?

As mentioned above, vitamin D is a major contributor to our immune system and bone health. You may know that having healthy levels of Vitamin D prevents rickets and helps to build strong, healthy bones. But you might be surprised to learn Vitamin D also helps(5):

  • Boost your immune system, helping you fight off colds, flu, and COVID-19
  • Improve enhanced intestinal permeability and lead to healthier digestion overall
  • Fight off cancer cells and tumors
  • Promotes a healthy libido
  • Protects the brain from dementia
  • Aids in the prevention of heart disease, depression, osteoporosis, Multiple Sclerosis, and possibly even Autism and other diseases

What Are Optimally Healthy Levels of Vitamin D?

It’s long been known that Vitamin D is produced in the skin when exposed to sunlight. And according to Harvard Health, increasing evidence concludes that many people living in the northern hemisphere may be Vitamin D deficient. “Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37°N [north of San Francisco, CA] or below 37°S [south of Aukland, NZ]. People who live in these areas are at relatively greater risk for vitamin D deficiency.”(3)  And that’s if you don’t wear any sunscreen. If you’re a sunscreen fan, all bets are off on getting any natural vitamin D.

The current AMA “normal” reference range says 20 nanograms/milliliter (ng/mL) to 50 ng/mL is considered “adequate for healthy people”. However, we need to keep in mind that the “normal” range is defined as ‘the average of a population’. And if the majority of the population is vitamin D deficient, do you really want your values to be “normal”? Probably not!

Also, “normal” isn’t the same thing as “optimally healthy”. So functional medicine takes optimal health into account and therefore considers a reference range of 40-60 ng/mL of Vitamin D to be optimally healthy. Functional medicine references ranges are typically narrower (ie: higher lows and lower highs) and are based on more recent clinical research studies.

Conditions Associated With Various Vitamin D Levels

  • Increased risk of toxic symptoms: >100 ng/mL (e.g. hypercalcemia), especially if not matched with adequate Vitamin K2 and magnesium intake (see below).
  • Increased Risk of Autoimmune Disease: 80-100 ng/mL
  • Slowing of cancer growth in patients with diverse types of cancer: 70-80 ng/mL
  • 50% Reduction in breast cancer, decreased risk of all solid cancers: 50 ng/mL
  • Optimal levels: 40–60ng/mL (varying by individual)
  • 300% greater risk of of multiple sclerosis: <40 ng/mL
  • Increased high blood pressure: <36 ng/mL
  • 200% greater risk of heart attack: <34 ng/mL
  • Sub-optimally Deficient: <30 ng/mL (increased inflammation, calcium loss from bones, osteoporosis, poor wound healing, increased muscle, joint and back pain, greater risk of depression, increased risk of allergies, diabetes, migraines, and schizophrenia, and increase in autoimmune disease like lupus, scleroderma, thyroiditis)
  • 75% greater risk of colon cancer: <20 ng/mL
  • Risk of rickets: <15 ng/mL
  • Notably deficient: <12 ng/mL

Do You Have Vitamin D Deficiency?

Can You Get Vitamin D From Your Diet?

Vitamin D is found in large quantities in fortified cereals. It’s also added to dairy products and a few other processed/packaged foods. However, it’s important to note that fortified foods use the cheaper version of this nutrient, Vitamin D2, rather than the more bio-available D3 form that the body actually needs. And unfortunately both D2 and D3 uptake in the same receptors in the body. So the more D2 you ingest, the less D3 your body can uptake. This can leave you with vitamin D deficiency if you eat a lot of fortified, processed foods or dairy that contain Vitamin D2.

You can also get a bit of Vitamin D3 in some whole foods. But with the exception of egg yokes and fish, many people these days aren’t eating a lot of the foods which are high in vitamin D3. Foods that are naturally high in vitamin D3 include:

  • Oily fish like herring, wild caught salmon, halibut, mackerel, and sardines
  • Cod liver oil (also has real vitamin A so this is a good way to get both, see below)
  • Egg yolks
  • Beer liver

Therefore, it is generally hard to get enough Vitamin D from food alone as it’s typically the wrong type (D2). Also, prescription vitamin D is usually D2, not D3. So if your doctor prescribes you Vitamin D in a prescription form, make sure to ask for D3.

Are you getting enough Vitamin D?

The USDA guidelines for adults recommend 600 IU per day. But those guidelines are old and much scientific research has been done since then. So today, many doctors and scientists believe that recommendation is too low. In fact, the government is currently looking at increasing that number to 1,000 IU per day with a high-end limit of 4,000 IU per day. And according to Chris Kresser, “The overwhelming majority of studies have shown that there is no risk of taking up to 8,000 IU of vitamin D per day.”(6)

If you live in North America or Europe, there’s a good chance you have vitamin D deficiency. The propensity for sunscreen use in the past 50-years has significantly reduced the amount of Vitamin D that people are producing through their skin from direct exposure to sunshine. Sunscreen aside, as mentioned above, most of the northern hemisphere and some of the southern hemisphere doesn’t get enough sunlight for most of the year for skin to create much Vitamin D at all. Many people in the United States, Canada, Europe, southern parts of South America and Australia, and New Zealand don’t ever get enough sunlight for their skin to produce enough vitamin D to stay healthy, even in the summer!

And after age 50 your body starts to produce less Vitamin D, even with optimal sun exposure. Plus, the darker your skin or the more skin you cover up with clothing or sunscreen, the less vitamin D your body will naturally be able to create through sun exposure.

According to a study by the Mayo Clinic(7), “The prevalence of patients with vitamin D deficiency is highest in the elderly, obese patients, nursing home residents, and hospitalized patients. The prevalence of vitamin D deficiency was 35% higher in obese subjects irrespective of latitude and age.” People with a Body Mass Index (BMI) of over 30 are typically vitamin D deficient. If you don’t know your BMI, you can calculate it with this BMI calculator.

So How Much Vitamin D Do You Really Need?

That’s a great question. And the answer is “it depends.” Bioindividuality – every BODY is different. Even two people living in the same house, eating the same diet, exposed to the same amounts of sun, may have very different needs. So it’s a great idea to have your doctor test you for Vitamin D deficiency with a blood lab for 25-hydroxyvitamin D, or 25(OH)D before you start supplementing. Since vitamin D is considered a ‘pre-hormone’ and interacts with ALL of your other hormones, you don’t want to supplement if you don’t need it.

When I had my Vitamin D levels tested about 10 years ago was shocked to find out I was extremely deficient. But in hindsight, it actually made sense, being a vegan at that time and living in the Pacific Northwest where we didn’t get much sun. My naturopath prescribed 10,000 IU per day of Vitamin D3. I’ve recently had my vitamin D levels re-tested, and even living in Mexico for five years, and taking 10,000 IU 3-4x a week, my levels are still at the low end of normal. So possibly I don’t absorb it well. Bioindividuality!

Unfortunately, some MDs who haven’t had much nutrition training may balk at this amount. One friend recently had her MD tell her she’d go into a coma if she took 10,000 IU. This is NOT true! Do your own research on pubmed.gov, and you’ll see it is very hard to get too much vitamin D if you live in the northern hemisphere.

Do yourself and your body a favor, and get your Vitamin D levels tested today. Then bone-up on your Vitamin D supplements if you are deficient.

Other Important Considerations When Supplementing with Vitamin D

If supplementing with vitamin D, you may also need to supplement with vitamin A, vitamin K, and magnesium which all work synergistically with each other. The body likes to be in homeostasis (balance). So if you supplement just with D, it can skew the values of the other nutrients your body needs.

For example, if you decide to supplement with Vitamin D3, it’s very important to ensure adequate levels of magnesium. Many Americans are deficient in magnesium, a vital mineral. According to the Journal of American Osteopathic Association, “Magnesium assists in the activation of vitamin D, which helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones.”(8) Magnesium is crucially important in the biochemical process to convert Vitamin D3 into its final usable form in the body.

And vitamin D and vitamin A also uptake in the same receptors. Because of this, it’s especially important to supplement with vitamin A if supplementing with Vitamin D.

Take Fat-soluable Supplements with Healthy Fats

Also, it’s important to note that vitamin D, A, and K are all fat-soluble vitamins and must be taken with healthy fats to absorb them. Healthy fats include olive oil, olives, avocados, avocado oil, coconut oil, nuts, seeds, and wild-caught fish. So if you’ve had your gallbladder removed or have congested bile ducts, gallstones, or hypothyroidism, you may not digest fats well. This means that even if you take fat-soluble supplements, you may not digest and absorb them without assistance from some digestive enxymes or ox bile. You may also need to consider sublingual forms of vitamin D or higher doses.

Last but not least, because vitamin D is a pre-hormone, it’s very important to titrate (ramp-up) slowly when you start taking supplements. This allows the body (and its vitamin D receptors) to adjust gradually over time. If you need more information or assistance with your vitamins, minerals, or other supplements, please reach out to schedule a coaching session. I’m happy to help.

Please leave a comment to let us know your experience with Vitamin D. Have you been tested? Were you diagnosed with vitamin D deficiency? Did supplements help increase your levels of vitamin D?


  1. https://www.nature.com/articles/s41598-020-77093-z
  2. https://crossfitsanitas.com/blog/vitamin-d-covid-19-chris-kresser
  3. https://www.health.harvard.edu/staying-healthy/time-for-more-vitamin-d
  4. https://www.drperlmutter.com/vitamin-d-parkinsons-disease/
  5. http://www.ncbi.nlm.nih.gov/pubmed/?term=vitamin+d+deficiency
  6. https://crossfitsanitas.com/blog/vitamin-d-covid-19-chris-kresser
  7. https://www.ncbi.nlm.nih.gov/books/NBK532266/
  8. https://jaoa.org/article.aspx?articleid=2673882

8 Responses to “Why Care About Vitamin D Deficiency?”

  1. Pam

    Great article Heidi…thanks

    • Heidi

      Thanks for your comment Pam, glad you liked the Vitamin D article! 🙂

  2. Kirsten

    I started taking vitamin D (in addition to my multivitamin and fish oil) because of this post and it has totally changed my life! I have so much more energy and my boyfriend noticed a big change in my cheerfulness. I’ve really enjoyed your posts and hope you keep sending them out.

    • Heidi

      Wow, thanks so much for the great feedback Kirsten! I’m so happy to hear what a positive difference Vitamin D has made in your life. Keep up the great self-care! 🙂

  3. magdalena

    I just read about the vit. D- that if we take to much, that increase the risk of kidney stones.
    Dr. Jennifer Ashton says that 1000 ui/day is enough.
    What’s your opinion about this?

    • Heidi

      Hi Magdalena, thanks for your comment. I’m not a doctor, so do not make recommendations on dosage. However, from what I have read and studied it appears to be very hard for people in North America and Northern Europe to get too much Vitamin D. With so many people wearing sunscreen these days, most people’s skin is unable to synthesize Vitamin D as it used to in the past. Personally, I take 5,000 IU/day from May through September, and 10,000 IU/day from October through April. I have been taking this amount for about 5 years now, get my levels checked once a year, and they are within the normal range. I recommend talking with your health care provider to determine what works best for your particular situation and geographical location, as well as getting 15 minutes of sunshine a day.

  4. Lybby moore

    Great info Heidi. Thank you

    • Heidi

      Glad you found it helpful Lybby! Thanks for reading and sharing.


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