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Your Vitamin D Supplement Might Not Be As Effective As You Think

Lauren Del Turco, CPT
May 23, 2023
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.
Portrait of a Young Woman With Eyes Closed and Enjoying The Sun
Image by W2 Photography / Stocksy
May 23, 2023

As awareness around the importance of vitamin D for a bunch of different aspects of our health grows, more and more people might consider adding a supplement to their daily routine. Seems like an easy enough investment in your health, right?

While the right vitamin D supplement can totally help you get your levels to an optimal place (and keep them there!), you won't reap much benefit from popping the wrong form of the important nutrient—or too little of it. And, sad but true: Research actually suggests that many of us might be making one or both of these supplement mistakes—and that they're keeping us from achieving the vitamin D status we need to feel our best.*

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Why optimal vitamin D status is so rare

Here's the deal, folks: Nationally representative data and robustly designed research1 on more than 26,000 adults in the U.S. (called the National Health and Nutrition Examination Survey, or NHANES) show that 41% of Americans are vitamin D "insufficient" [meaning they have serum 25(OH)D levels less than 30 ng/ml], while 29% are flat-out "deficient" (their levels are less than 20 ng/ml).

Note: Optimal vitamin D status is 50 ng/ml plus (for more info, check out this article).

The numbers are pretty alarming—and what's even more alarming is that they take into account all of the different ways we can get vitamin D, including foods and drinks (including fortified products like milk and OJ), the sunand supplements.

"This raises the question: How insufficient are most people's vitamin D supplements? Very," says mbg's VP of scientific affairs Ashley Jordan Ferira, Ph.D., RDN. "This national statistic suggests that many people aren't supplementing and are instead relying on vitamin-D-scant diets and unreliable sun exposure and that those who are taking supplements are consuming sub-efficacious supplement doses."

Basically, the current state of vitamin D supplementation in the U.S. clearly isn't doing enough to prevent these staggering rates of insufficiency and deficiency (which are most likely to affect minorities, people who have overweight or obesity, and the physically inactive, by the way).

A few factors that might explain why taking supplements may not be enough to move the needle on our vitamin D status:

  • A too-low dose: "The minimum effective dose for an adult with optimal blood levels of vitamin D is about 3,000 IU, with many supplements including less than this," explains functional nutrition dietitian Whitney Crouch, RDN, CLT. "Given that about 70% of Americans are insufficient or deficient, the actual need for most people is likely 5,000 to 10,000 IU daily until blood levels are optimal.*"
  • The wrong form: "Many vitamin D prescriptions given by doctors are vitamin D2, which is not a form of vitamin D that the body can easily use," Crouch notes. Here's why the D3 form triumphs over D2 every time.*
  • Improper administration: "Many people aren't aware that vitamin D is a fat-soluble vitamin, meaning that it either needs to be taken with food that contains some fat or be designed to include healthy fat in the formula," she adds. (mbg's vitamin D3 potency+ is expertly formulated with three organic oils so that you can take it anytime, with or without food.)*
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Bottom line: These statistics suggest that we can't expect willy-nilly vitamin D supplementation to guarantee healthy levels and—that many of us need to take a much more diligent, specific approach to boosting our intake of the sunshine vitamin.

The takeaway

"For people with known low vitamin D levels, I typically recommend choosing a vitamin D3 supplement of 5,000 IU and taking it daily for eight to 12 weeks before retesting blood levels," suggests Crouch. "That said, seasons of the year, typical sun exposure, skin tone, and body fat should all be considered, as these traits could increase a person's supplement needs."*

Of course, there is a place for some of the lower-dose vitamin D supplements you see out there (think anything less than 3,000 IU)—specifically when someone is taking multiple supplements that contain vitamin D3, like a multivitamin and a bone or immune health supplement, highlights dietitian Jess Cording, M.S., R.D., CDN.* A lower-dose product can also be an easy way to augment your current D routine in the winter months, she suggests.

In these cases of multiple D inputs, Ferira explains that you'll want to "think of your daily D3 supplement as your critical foundation to achieve and maintain healthy vitamin D levels, and approach the lesser but useful bits of vitamin D from a multivitamin, immune complex, diet, and sunshine as a complementary, extra bonus if you will."*

Generally, though, you probably need to take more vitamin D than you thinkespecially if you have insufficient or deficient levels since even those with already-healthy levels need 3,000 IU per day just to avoid dipping into a state of insufficiency. Consider a high-potency option, such as mbg's vitamin D3 potency+ (which offers 5,000 IU of sustainable organic algal vitamin D3) or another one of our favorite vitamin D supplements.* (And for more product recommendations, check out our vitamin D supplement roundup.)

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.