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Truly Optimal Vitamin D Levels Are Higher Than You Might Think

Lauren Del Turco, CPT
September 19, 2021
Lauren Del Turco, CPT
Written by
Lauren Del Turco, CPT
Lauren Del Turco, CPT is a freelance health and wellness writer, editor, and content strategist who covers everything from nutrition to mental health to spirituality.
September 19, 2021

Vitamin D is a hot topic these days, and given the many (really, many!) roles it plays in the body, it's well-deserving of the attention. The thing is, though, there's still a bit of confusion out there about how much vitamin D we really need—and what levels we should maintain in our body for truly optimal health for life.

To help you achieve vitamin D sufficiency for life (which all good science shows requires supplementation), let's clear up just where you want your vitamin D levels to be—and stay.*

What is vitamin D?

Vitamin D is a fat-soluble vitamin, preprohormone, and full-on hormone (i.e., in its active form in the body) that's essential for whole-body health.* Vitamin D3 is synthesized in our skin from UVB sunlight exposure, which is how it earned its nickname "the sunshine vitamin."

We can also get some vitamin D from specific foods (though, not nearly enough to support sufficient vitamin D status).

Vitamin D supplements are also popular (and critical) for people who aren't able to get enough from sunshine or food (i.e., pretty much all of us) and individuals interested in reaching and maintaining vitamin D sufficiency throughout life.*

How vitamin D levels are measured.

Let's begin with a quick breakdown of how doctors and researchers measure vitamin D levels (aka, your vitamin D status) in the body. When you ask your doc to test your vitamin D, they perform a blood test to measure your serum total 25-hydroxyvitamin D, or 25(OH)D, for short, explains mbg's director of scientific affairs Ashley Jordan Ferira, Ph.D., RDN.

Quantified in nanograms per milliliter (ng/ml) units, Ferira explains that, "your 25(OH)D level is a biomarker that reflects your whole-body vitamin D status from circulating blood levels. Vitamin D is the starting vitamin input, and that essential micronutrient is hydroxylated in your liver to 25(OH)D to travel around the body, available to your various organs for a variety of critical health functions."*

She goes on to say, "Some people track their blood pressure as an indication of cardiovascular health. I'm one of those people, but I also track my 25(OH)D level at least annually to inform my vitamin D health state. It's that important."

The confusion around optimal vitamin D levels.

If you've ever had your serum vitamin D levels tested or done a quick search online about healthy levels, you've probably come across the idea that 30 ng/ml is the goal—but that's not really the case. In truth, 30 ng/ml is just the bottom cutoff for vitamin D "sufficiency."1

Ferira puts it this way: "I personally don't like to confuse folks by even mentioning 30 ng/ml in the same breath as 'vitamin D sufficiency.' I prefer to think of 30 as the risk or warning zone. It's the cutoff for inadequacy, so you don't strive for it, you avoid it with intention."

"This is the bare minimum level to avoid major issues known to occur with vitamin D deficiency, including bone issues and poor thyroid health," explains board-certified endocrinologist Brittany Henderson, M.D., who specializes in hormones (including vitamin D) in her clinical practice. That said, "higher levels of serum 25(OH)D have consistently been associated with improvements in mood, enhancement of the immune system, and more." 

Unfortunately, a large chunk (41%) of the U.S. adult population2 is in the "warning zone" (< 30 ng/ml), and they probably don't even know it. This means they are vitamin D insufficient. Another term used is hypovitaminosis D. To make it simple, not enough vitamin D.


While the clinical 25(OH)D level is 30 ng/ml, leading functional medicine experts recommend achieving and maintaining vitamin D levels of 50 ng/ml or higher for optimal whole-body health.

Why 50 ng/ml is the vitamin D goal for life.

So if 30 ng/ml really doesn't cut it for optimally supporting your health and well-being, what vitamin D levels should you strive to achieve and maintain?

"As an endocrinologist, I know that achieving optimal serum 25(OH)D levels in the 50+ ng/ml range is imperative for immune health, bone health, and more," Henderson says. "This is the average or median level at which most association studies show various benefits, including immune health, balanced mood, and more."

And the tool to achieve that level of 50 ng/ml is clearly vitamin D3 supplementation, according to Henderson's clinical expertise with hundreds of patients (plus, the collective D science to date).*

While hitting 30 ng/ml is a start (especially if you're starting out with levels below 20 ng/ml, which means you're clinically deficient1), it's not the goal.

"We are consistently undertreating patients when we stop at 30 ng/ml," Henderson continues. "Our population is heavily vitamin D deficient and targeting an optimal level of 50 ng/ml has an enormous impact on all aspects of human health."

Ferira adds this analogy: "Aiming for 30 ng/ml is like signing up and paying for four years of college but never attending any classes, taking any tests, or graduating. It's a bad investment, aims too low, and is going to hurt eventually."

How to actually hit (and maintain) 50 ng/ml.

If you think relying on food and sun alone will help you reach that 50 ng/ml mark (and stay there), newsflash for you: It's just not possible (with food) and unwise (with sun).

Ready for a little math? Ferira breaks it down for us: "Pharmacokinetic research3 shows that it takes 100 IU of vitamin D to increase a normal-weight adult's serum D levels by about 10 ng/ml. So, that means that in order to achieve 50 ng/ml, you need 5,000 IU of vitamin D per day."

Considering a three-ounce serving of trout4 (which is the best whole-food source of vitamin D out there) only offers 645 IU and that a number of factors (such as your skin tone and where you live) prevent most people from getting significant amounts of vitamin D from the sun, you're left with one stellar option: a high-quality, high-potency vitamin D supplement.*

That means vitamin D3, which is the body's preferred form.* "The formulation of vitamin D3 is the most important variable," says Henderson. "It has to be packaged as highly bioavailable or it just won't work!"

Specifically, "since vitamin D is a fat-soluble vitamin, it is important that it be packaged with fats for maximal absorption,"* she adds. And, remember, you'll need 5,000 IU per day to hit that 50 ng/ml mark.

Not many supplements check all of these boxes, which is why mbg formulated vitamin D3 potency+ to provide 5,000 IU of vitamin D3 (from a sustainable, plant-origin source: algae!), plus a trio of healthy organic fats from extra-virgin olive, flaxseed, and avocado oils.*

When should I test my vitamin D levels?

So, how often should your doc test your vitamin D status? You might be surprised by the answer. It turns out that you can start a vitamin D3 supplement routine before or after you test your 25(OH)D level. Ferira explains: "Getting a baseline 25(OH)D test result is informative but in no way imperative. In reality, the daily D3 supplementation practice is way more important than an overzealous tracking of your serum status."

If you're able to get a baseline 25(OH)D test, great. It will help you track the progress of the supplement so your health care provider can help pivot and individualize your dosing as needed. "For example, folks with more body fat will require proportionately more vitamin D1, about two to three times more, per the science,"* says Ferira.

In terms of follow-up testing, Henderson recommends retesting your vitamin D status every eight to 12 weeks and working with your health care practitioner to make any tweaks needed.


Once starting your supplementation regimen, board-certified endocrinologist Brittany Henderson, M.D. recommends testing your vitamin D status every eight to 12 weeks.

The takeaway.

Scientific literature and health experts assert that 50+ ng/ml, not 30 ng/ml, is the optimal serum vitamin D level we should all strive for to support our health and well-being. Achieving it requires supplementation with a high-potency vitamin D3 product (like mindbodygreen's vitamin D3 potency+) that either provides or is taken alongside healthy fats to support optimal absorption.*

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
Lauren Del Turco, CPT author page.
Lauren Del Turco, CPT

Lauren Del Turco, CPT is a freelance health and wellness writer, editor, and content strategist who covers everything from nutrition to mental health to spirituality. Del Turco is also an ACE-certified personal trainer. She graduated from The College of New Jersey with a Bachelor of Arts in English and Creative Writing. When she’s not on deadline, you’ll find Del Turco hiking with her dogs, experimenting with new plant-based recipes, or curled up with a book and tea.