Don’t “fall back” on your vitamin D intake this winter

As we creep further into the cold, dark days of winter, there’s another urgent health concern—outside of seasonal affective disorder (SAD)—that you should be aware of.

Of course, I’m talking about a heightened risk of vitamin D deficiency.

But today, I won’t be focusing on the usual dangers of low D levels—like an increased risk of cancer, fractures, or heart disease. Instead, I’d like to share with you the results of another new study that shines a spotlight on a particularly urgent threat facing us this winter…

Most COVID-19 patients are D deficient 

I’ve talked before about the unique threat that low levels of vitamin D pose in this pandemic—from a higher risk of severe complications to a higher risk of infection in general. And today’s research underscores that lethal link in bold, red ink.

A recent study in the Journal of Clinical Endocrinology & Metabolism reported on more than 200 COVID-19 patients at Hospital Universitario Marqués de Valdecilla in Spain. And researchers found that more than 80 percent of these patients were critically deficient in vitamin D.

On the whole, men had lower levels of vitamin D than women. And COVID-19 patients with low vitamin D levels were also more likely to have higher levels of key inflammatory markers, like ferritin and D-dimer.

Of course, there’s absolutely nothing surprising in these findings. But with another daylight savings behind us, I’ll use this stark opportunity to remind you that you should consider resetting your supplement dosage right alongside your clocks.

High doses aren’t just safe—they’re necessary

It’s no wonder that rates of D deficiency double during the winter. (If you’re suffering through a New York winter like me, there will be days when you don’t even see the sun at all.)

So first things first: Get your current blood levels tested to get an idea of where you’re starting. If your doctor hasn’t given you a 25-hydroxyvitamin D test recently (or ever), I encourage you to make an appointment now and ask for one. (I also recommend getting your levels screened every 6 months to ensure you are maintaining optimal levels.)

Just bear in mind that most labs will indicate a level of 30 ng/mL is sufficient. But if you’ve been a reader of mine for a while now, then you know that isn’t good enough. I like my patients’ levels to be between 80 and 100 ng/mL—because really, that’s where all the health benefits kick in. You’ll most likely need at least 2,000 to 5,000 IU of D3 per day to maintain those levels.

But I often prescribe as much as 10,000 IU of vitamin D3 daily to my patients. (I personally take 10,000 IU every day myself.) Higher doses are particularly necessary in the winter, when sunlight exposure takes a nosedive.

Supplementing with vitamin D—even in “high doses”—is very safe. And if you’re working closely with your doctor (as you should), there’s really no reason to take any less.

I test my D deficient patients every six weeks until they get where they need to be—and I test the rest of my patients twice per year. So, make sure your doctor does the same. Because this winter, the stakes are simply too high to cut corners.

In addition to supplementing with optimal levels of vitamin D, I also outline all of my top immune health recommendations to help battle the upcoming cold, flu, and coronavirus season in my Complete Guide to Year-Round Immunity. To learn more about this comprehensive guide, click here now!


“Over 80 percent of COVID-19 patients have vitamin D deficiency, study finds: Vitamin D deficiency was more prevalent in men.” Science Daily, 10/27/2020. (