Why taking a “summer vacation” from your vitamin D supplement is a BIG mistake

According to experts, up to 75 percent of Americans don’t get enough vitamin D each day. And that’s major problem, as having optimal blood levels of this crucial nutrient can protect you against just about every chronic disease on the planet.  

And now, a new study just found that supplementing with even miniscule doses of the “sunshine vitamin” offers significant protection against respiratory infections, like those caused by the coronavirus. 

Let’s get right to it…  

New meta-analysis includes unpublished data 

Four years ago, researchers from Karolinska Institute in Sweden, Harvard Medical School, and Queen Mary University in London analyzed the impact of vitamin D supplementation on respiratory infectionsusing data from 25 previously published clinical trials 

Their initial analysis showed that vitamin D supplementation did indeed have a protective effect against respiratory infections. However, the researchers felt they couldn’t fully embrace the results since most studies only get published if they show a clear, positive effect…and, in contrast, most of the studies showing no effect never get published. 

So, last year, they went back to the drawing board and included 18 unpublished studies into their analysis to alleviate any possible “publication bias.” 

This second analysis was published in The Lancet. It included data from 43 clinical trials and nearly 49,000 participants.  

Overall, the researchers found that: 

  • People who took daily doses of just 10 mcg (400 IU) to 25 mcg (1,000 IU) of vitamin D had a 42 percent lower risk of getting aacute respiratory infection(Note: That daily dose is far lower than the optimal amount you should take daily, year-round. Keep reading for my exact dosing recommendations.) 
  • Daily doses were much more effective than were weekly or monthly doses of vitamin D. (Isome medical practices, doctors will give vitamin D in weekly or monthly doses for convenience.) 

The new study did not confirm a prior finding that protection was more pronounced in those who had the lowest vitamin D blood levels at the start of the trials(So, apparently, you don’t have to have a deficiency to get a major boost.) However, it did confirm, once again, that vitamin D supplementation does not cause any adverse side effects or reactions. 

Vitamin D supports a “balanced” immune response 

According to lead researcher, Dr. Adrian Martineau, vitamin supplementation seems to prevent infections in three ways: 

1.) It supports balanced immune response. 

2.) It boosts a range of helpful anti-microbial immune actions. 

3.) It dampens intense and potentially harmful excess immune reactions.  

Put another way, it seems that vitamin D helps the body go after the harmful, invading microbes…but it doesn’t cause the body to overreact to the invasion. And that’s key, especially when it comes to the coronavirus.  

In fact, according to the frontline workers and researchers, people who develop the most severe cases of COVID-19 seem to have an intense, overreaction by their immune system to the virus.  

To learn more about vitamin D’s effect on coronavirus, specificallyDr. Martineau and his team are currently conducting a study with 6,200 participants in the U.K. And while I’m pleased to hear that this research is taking place, I have to wonder why they can conduct these types of important studies in the U.K., but not in the U.S.? 

What does it all mean for you? 

In addition to helping you guard against colds and viruses, it’s clear that vitamin D helps prevent and fight against just about every chronic disease in the book. So, do yourself a huge favor and take action toward bettering your health—starting today.  

You can get started with these three simple steps:  

1.) Ask your doctor to check your vitamin D levels twice a yearI recommend getting your vitamin D levels checked once toward the end of winter and again toward the end of summer. Just ask for a simple blood test called the 25(OH)D (25-hydroxy vitamin D) test. Optimal blood levels are between 50 and 75 nanograms per milliliter (ng/mL).   

2.) Supplement daily with 250 mcg (10,000 IU) of vitamin D3. You can now find this dose in a convenient, highly absorbable liquid form—together with the potent marine carotenoid astaxanthin for added benefits. (For more information, simply type “astaxanthin” into the topright search bar of my website, www.DrMicozzi.com.) 

3.) Spend 15 minutes a day in the sunwithout sunscreenNow, I know at this time of year, you may spend more time in the sun and think it’s okay to take a “summer vacation” from supplementing with vitamin D. But that’s a big mistake. Here’s why…  

For one, even with some summertime sun exposure, most people still don’t get enough vitamin D to reach optimal blood levels of this critical nutrient. Secondly, since vitamin D is a fat-soluble vitamin, you can and should supplement year-round to store it away (literally) for a rainy day. Third, theres no risk of “overdose.” Even at this time of year, your skin cannot make too much vitamin D from sun exposure, since there is an automatic, biological “shut-off” mechanism when you get enough. 

At the end of the day, vitamin D is hands-down one of the most important supplements. In fact, if you could only take only one supplement from here on out, it would absolutely be the one.  

To learn more about vitamin D3 and its disease-fighting benefits, I encourage you to visit my website, where I’ve written about it for nearly 10 years now, right here in my Daily Dispatch and in my monthly Insiders’ Curesnewsletter. (And keep an eye out for my newest feature on the subject in the upcoming June issue!)  


Vitamin D supplementation to prevent acute respiratory infections: a systemic review and meta-analysis of aggregate data from randomized controlled trials.” The Lancet, 3/30/21; 9(5):276-292. doi.org/10.1016/S2213-8587(21)00051-6