A PhD & RD Debunks 4 Common Vitamin D Myths

Another pet peeve of Ferira’s? When people declare that vitamin D is toxic simply because it’s fat soluble. “That is like a 1982 science textbook. We’re in 2021—we need to stop making these sweeping statements,” she says. While vitamin D toxicity is possible, it’s much more challenging to reach than you might think, and it’s not even relevant at useful, science-backed supplement doses (like 5,000 IU per day). 

We explain the reasoning in full here, but let’s go over the highlights: Unless you’re taking mega, mega amounts of vitamin D, toxicity isn’t actually a concern. Clinical trials have found that toxicity considerations can happen with a serum 25(OH)D concentration greater than 150 ng/ml. That is three times higher than the range clinicians typically recommend (50 ng/ml) for vitamin D sufficiency. 

“The actual clinical science shows that you could even take 20,000 to 50,000 IU of D3 a day, and not only is it not toxic, but these amounts helped the participants actually raise their blood levels to sufficiency,”* says Ferira. “I’m not saying that’s your level, but it was successful—not scary.” 

The takeaway? Getting too much vitamin D is extremely difficult, and it’s high time brands offer formulas with realistic apprehensions for toxicity, rather than erring on the low, low side of the spectrum (and not helping folks meet their vitamin D needs as a result).