Debunking D: 5 Myths About Vitamin D That Even We Were Duped By

Although vitamin D is known as the "sunshine vitamin," it's simply not possible to get all the vitamin D we need from sunlight while following safe sun exposure practices. 

So if we're working an office job and spending most of our time indoors, we should increase the number of vitamin-D-rich foods in our diet, right? In most situations, this is a very logical and effective approach to filling nutrient gaps—but vitamin D sufficiency isn't so easily achieved.

Unfortunately, even the foods richest in vitamin D don't provide high enough quantities to meet our daily needs. For example: Trout is the richest food source of vitamin D available and only provides 645 IU of D per 3-ounce serving. Each day, you'd need to eat approximately 23 ounces of trout, 7 cups of irradiated (UV-treated) mushrooms, or 125 slices of cheese to meet 5,000 IU of vitamin D—a dose level tied to vitamin D sufficiency in adults with a normal BMI.

Clinically speaking, these ranges are the standard—and we have a few qualms with that. Trusted nutrition and health experts agree that we need levels at or above 50 ng/ml to provide the vitamin D our bodies need to optimally carry out physiological functions. 

The fact is that 30 ng/ml is simply the cutoff for threat of deficiency, not the number you want to aim for. Many health care providers take folks off of their vitamin D supplement once they reach 30 ng/ml. This leads to what mbg's vice president of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, calls yo-yoing, or bouncing back and forth between vitamin D insufficiency and sufficiency. 

While 1,000 IU of vitamin D a day might seem like a large quantity, if the goal is achieving and maintaining vitamin D sufficiency, this dose is sub-efficacious when compared to higher potency dosages like 5,000 IU and 10,000 IU. And if your current vitamin D status is below 30 ng/ml, a low dose like 1,000 IU simply isn't enough to get your levels above 30 ng/ml, much less in the winning range of around 50 ng/ml. (Ferira previously explained the vitamin D math here.)

Research published by the Clinical Journal of the American Society of Nephrology3 reporting on the important research by the late vitamin D advocate and bone health expert Robert P. Heaney, M.D.,4 demonstrates that taking 1,000 IU daily (of D3, not D2, which is less potent) will only raise 25(OH)D levels approximately 10 ng/ml. This simply isn't enough if you're dealing with vitamin D insufficiency or deficiency—or trying to maintain vitamin D sufficiency, for that matter.*

Indeed, a high-potency vitamin D supplement of 5,000 IU per day is ideal for most people; or doubling up may be necessary, as individuals may require more or less depending on their unique biology, body composition, and health considerations. 

While vitamin D toxicity (aka hypervitaminosis D) is possible, actually reaching toxic levels of vitamin D is an absurdly difficult thing to do. Let's bust this myth, shall we?

As you can see in this 2018 review published in Frontiers in Endocrinology5, the Institute of Medicine and the Endocrine Society have both concluded that 25(OH)D concentrations in our blood need to exceed 150 ng/ml to ignite a legitimate concern of vitamin D toxicity. That's three times higher than the goal for true sufficiency (and it would take some serious effort or an accident to get there)! 

If you haven't caught on by now, vitamin D supplementation at the proper dosage is vital to achieving vitamin D sufficiency.* It's not all about the IU, though—form and function play a massive role in how effective your vitamin D supplement can be.

When it comes to bioavailability, choose vitamin D3 (cholecalciferol) over D2 (ergocalciferol) every time. The efficacy and stability of D3 simply can't be matched by D2. You may also want to consider the sustainability of your vitamin D3 source. There are plant-origin, organic options now—like the organic vitamin D3 derived from algae in mbg's vitamin D product.

To further support the absorption and effectiveness of your D3 supplement, make sure you're taking this fat-soluble micronutrient with a fat source. Or better yet, choose a thoughtfully designed supplement with healthy fats built right in—like mindbodygreen's vitamin D3 potency+, which includes an organic trio of olive, avocado, and flaxseed oils to aid absorption.* For more supplement recommendations, check out our vitamin D roundup.

There's a lot of folklore out there about vitamin D. Figuring out best practices can be a little confusing when it comes to getting enough vitamin D, but a high-quality supplement—like mindbodygreen's vitamin D3 potency+—can help cover all the bases.