Published on January 24, 2022

The Front Line COVID-19 Critical Care Alliance (FLCCC) emphasizes the extreme importance of optimizing vitamin D levels to >50 ng/ml with a recommended vitamin D treatment schedule

Key Points

  • Vitamin D is listed as the first priority nutritional supplement in the pre-and post-exposure (I-MASK+) protocol for COVID-19
  • It is extremely important to dose vitamin D based on the baseline vitamin D level in order to reach the target vitamin D level, suggested to be a minimum of 50 ng/ml (125 nmol/L) for the greatest protection against COVID-19 disease severity and death
  • Two new tables have been included to help individuals determine a safe and practical vitamin D treatment schedule for increasing vitamin D levels

The Front Line COVID-19 Critical Care Alliance (FLCCC), a non-profit organization formed by leading critical care specialists in March 2020, continually updates their recommended approach to COVID-19 prevention, treatment, and recovery based on findings from the most recent research. Their protocol for treatment is meant as a guideline for physicians, and while they suggest that individuals consult with their health care providers before starting the medical treatments suggested, there are several therapies recommended that can be utilized safely from home for prevention and early treatment – including the newly updated protocol for optimizing vitamin D.

Vitamin D Listed as First Priority Nutritional Supplement

Vitamin D is listed as the first priority nutritional supplement in the pre-and post-exposure (I-MASK+) protocol for COVID-19. According to the FLCCC Alliance – COVID-19 Management Protocol overview document, “Vitamin D has numerous immunological properties that play a vital role in limiting the acquisition and severity of COVID-19.” Many studies have demonstrated the effect of vitamin D supplementation and serum level on COVID-19 outcomes and support the concept of the greatest benefit from vitamin D being among those who are currently deficient or insufficient in vitamin D – making the testing of vitamin D levels of incredible importance.

“The OPTIMAL Target Vitamin D Level is >50 ng/ml”

In their latest guide, the FLCCC recognizes the unique dosing requirements needed for each individual, and that dosing amounts should be based on a person’s baseline vitamin D level. “It is therefore EXTREMELY IMPORTANT to stress that the optimal regimen for vitamin D supplementation for both the prophylaxis and treatment of COVID-19 should be based on the baseline vitamin D level.” The target vitamin D level suggested is a minimum of 50 ng/ml (125 nmol/L) for the greatest protection against COVID-19 disease severity and death.

The table below gives an example of a “safe and practical treatment schedule” to increasing vitamin D levels in non-urgent situations when a baseline vitamin D level is known. Large doses, such as those listed as an Initial Dose, are suggested to be broken down into doses of 50,000 IU per day over several days to help improve bioavailability and conversion. (For example, the 200,000 IU Initial Dose could be taken as 4 daily doses of 50,000 IU at the beginning of the first week of supplementation.)  The Weekly Dose can then begin the first day of the second week of supplementation, taken as indicated (50,000 IU each day for X days each week).  Re-testing vitamin D levels after 2-4 weeks is suggested by the authors when using the following treatment schedules to assure a vitamin D level of at least 50 ng/ml has been achieved.  It is also important to maintain the achieved vitamin D level with a daily maintenance dose of vitamin D, and follow up with vitamin D testing every 6 months to make sure the level remains within target.

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The following vitamin D treatment schedule is suggested when the baseline vitamin D level is not known.

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In addition, the authors suggest supplementing with vitamin K2 and 250-500 mg per day of magnesium, when taking more than 8000 IU of vitamin D per day.  Also note that several other nutrients, such as vitamin C and zinc, are important to include for the best immune health and protection against COVID-19.

The same treatment schedule is recommended as a first line therapy for those with post-COVID syndrome or long-haul COVID.

For the full, current I-MASK+ protocol (version 19, updated on JANUARY 19, 2022) in multiple languages, click here.

Using the Vitamin D*Calculator

Another personalized vitamin D dose calculation option is to use the GrassrootsHealth Vitamin D*calculator, which calculates customized daily vitamin D doses based on an individual’s current vitamin D level (if available), target vitamin D level, weight, and current vitamin D intake. One difference between the tables provided above and the calculator is that the customized loading dose given by the D*calculator is divided into doses of 25,000 IU spread over a number of days to achieve the initial increase in vitamin D level. The calculated maintenance dose can then be taken on a daily basis to help maintain the achieved level, which is capped at 10,000 IU per day to match the No Observed Adverse Effect Level (NOAEL).

When Might Vitamin D Toxicity be a Concern?

Vitamin D levels above 150 ng/ml (375 nmol/L) begin to raise the concern for vitamin D toxicity, which is most frequently diagnosed when levels are over 200 ng/ml (500 nmol/L), though not everyone who reaches that level experiences toxicity. Vitamin D toxicity occurs when high vitamin D levels cause high calcium levels, called hypercalcemia. Symptoms of hypercalcemia include loss of appetite, feeling very thirsty, weight loss, constipation or diarrhea, abdominal pain, musculoskeletal pain, or feeling sick, confused, or tired.

According to a Mayo Clinic publication, “There is enough evidence that vitamin D toxicity is one of the rarest medical conditions and is typically due to intentional or inadvertent intake of extremely high doses of vitamin D (usually in the range of >50,000 – 100,000 IU/day for months to years) without monitoring for hypercalcemia.” In fact, a meta-analysis of 15 clinical trials found no toxicity below a vitamin D level of 200 ng/ml (500 nmol/L) or below a vitamin D intake of 30,000 IU/day.

Measure Your Vitamin D Level At Home through the GrassrootsHealth Project

Having and maintaining healthy vitamin D levels and other nutrient levels can help improve your health now and for your future. Choose which additional nutrients to measure, such as your omega-3s and essential minerals including magnesium and zinc, by creating your custom home test kit today. Take steps to improve the status of each of these measurements to benefit your overall health. You can also track your own intakes, symptoms and results to see what works best for YOU.

Enroll and test your levels today, learn what steps to take to improve your status of vitamin D (see below) and other nutrients and blood markers, and take action! By enrolling in the GrassrootsHealth projects, you are not only contributing valuable information to everyone, you are also gaining knowledge about how you could improve your own health through measuring and tracking your nutrient status, and educating yourself on how to improve it.

What Does it Take YOU to Get Your D to 40 ng/ml (100 nmol/L)?

Did you know your health could be greatly affected by making sure you have a vitamin D level of at least 40 ng/ml (100 nmol/L)? Help us help you.

STEP 1 - Do you know what your vitamin D level is? If not, be sure to test today to find out.

STEP 2 – Determine your target level. Are you at your target level? Experts recommend a level of at least 40-60 ng/ml (100-150 nmol/L).

STEP 3 – Need to boost your level? Use the D*calculator to see how much vitamin D it may take to reach your target. Opt for the Loading Dose for a quicker boost.

STEP 4 – Optimize how your body absorbs and utilizes vitamin D with co-nutrients and these simple steps.

STEP 5 – Re-Test! This is an important step to make sure you have reached your target level, and to ensure you are not taking too much! Re-testing after 3-4 months is recommended.

STEP 6 – Adjust, Repeat…

Give your immune system the nutrients it needs to support a healthy you and protect yourself from unnecessary diseases, especially COVID-19.


The first Randomized Controlled Trial on vitamin D and COVID-19 has shown a 96% lower risk of ICU admission for those receiving vitamin D (as 25(OH)D to quickly boost vitamin D blood levels) along with the standard treatment, compared to those receiving standard treatment alone.

These results support many previous observational studies showing a relationship between vitamin D levels and intake and COVID-19 severity.

Review the Latest Nutrient Research for COVID-19

GrassrootsHealth Nutrient Research Institute has launched the new Immune Boost project with the use of our myData-myAnswers nutrient health system that nearly 15,000 people are already using for their health. Specific markers that influence immune health are suggested for testing as part of this project including:

  • Vitamin D
  • Omega-3 Index
  • Essential elements magnesium, selenium, and zinc
  • hsCRP

Our goal is to demonstrate how one can use the Nutrient Research Model established by Dr. Robert Heaney to show the effect of vitamin D serum levels of at least 40 ng/ml (100 nmol/L) on risk reduction for all ethnicities in the population. Status and intake of other nutrients will also be analyzed for any type of relationship to immune status and symptom severity. Join the project today!

Please let us know if you're interested in helping sponsor this project.

CLICK HERE for updates and new information about the project.

Through GrassrootsHealth Nutrient Research Institute, you can also test your essential elements magnesium, copper, zinc and selenium, toxins such as lead, mercury and cadmium, as well as your omega-3 levels, inflammation levels and thyroid stimulating hormone (TSH) level. Find out your levels today! Log on to the test selection page (click the link below) to get your tests and see for yourself if your levels can be improved.

Make sure you track your results before and after, about every 6 months!

Click Here to Access the Test Page

How can I track my nutrient intake and levels over time?

To help you track your supplement use and nutrient levels, GrassrootsHealth has created the Personal Health Nutrient Decision System called

For each specific supplement, you can track what days you take it, how much, and many other details.  This will help you know your true supplemental intake and what patterns of use work for you to reach and maintain optimum nutrient levels. Check it out today!