coldflu_updated 090616In an analysis of GrassrootsHealth D*action data, participants who have a vitamin D level of at least 40ng/ml (100 nmol/L), cut their risk of cold and flu by 15% and 41% respectively compared to those with levels <20 ng/ml.

What does other research say?

Listen to this webinar  by one of our international scientist panel members, Dr. Carlos Camargo, as he explains four key randomized controlled trials done in 2012 on vitamin D and respiratory infections.

The first trial he covers has over 3,000 children, aged 1-11 months. The children were given a bolus dose, 100,000 IU, every 3 months for 18 months. There was no change in infection rates between the vitamin D group and the control group.

Dr. Camargo participated in the research in the  second study presented which involved 744 children in Mongolia. The study team gave the children a daily serving a milk; the study group received  milk that was fortified with 300 IU of vitamin D, and the control group had milk with no added vitamin D. At the start of the trial the average vitamin D level of the children was 7 ng/ml;  over the three-month trial the vitamin D group moved to 19 ng/ml. The result was that the vitamin D group had about half the infections of the control group – it worked! There are two key points that contribute to the success of this study, the first is the children were all very deficient at the start and the second was the daily, rather than monthly, dosing.

Dr. Camargo was also involved in the third study presented in which 322 healthy adult New Zealanders were given 100,000 IU per month for 18 months. There was no difference in this study between the vitamin D group and the control group. Camargo surmises it is because the subjects were so healthy, had an average vitamin D level at the start of  29 ng/ml, and possibly because of the bolus dosing.

The last study presented used data from 140 adult patients at an immunodeficiency clinic. Each participant in the vitamin D group took 4000 IU/day for 12 months while the control group were given placebo, no vitamin D). The researchers looked at their “infection score” which was defined by five different factors, vitamin D level was considered a secondary endpoint. The average level at the start of the study was about 20 ng/ml and moved up to 50 ng/ml in the vitamin D group by the end. After a year the vitamin D group did have a lower rate of infections and the difference was statistically significant.

Bolus vs. Daily dosing

It seems from these studies that daily dosing is better than bolus dosing when it comes to protection against respiratory infections. There is also a difference between a starting level of 15 ng/ml and one of 40 ng/ml. The lower you start, the more benefit vitamin D will have.

How can you reduce your chance of colds and flu?

We recommend you take, or get, your vitamin D daily – as nature intended – and pair it with a healthy lifestyle. It is recommended that you test your level twice a year, at the end of summer and the end of winter, until you know what routine will work for you to maintain your level between 40-60 ng/ml (100-150 nmol/L).

carmargo - vitamin D quote


Scientists Answer Your Questions
Webinar hosted by GrassrootsHealth
What vitamin D level helps prevent upper respiratory infections?
Dr. Carlos Camargo
February 2013
Watch Part 1 (30 minutes – 15 minutes then Q&A)
Watch Part 2 (8 minutes – continued Q&A)

Effect on the incidence of pneumonia of vitamin D supplementation by quarterly bolus dose to infants in Kabul: A randomized controlled superiority trial
Negative study – bolus dosing
Manaseki-Holland et al.
Lancet 2012
Read Study

Randomized Trial of Vitamin D Supplementation and Risk of Acute Respiratory Tract Infection in Mongolia
Positive study – 50% less infections in vitamin D group
Camargo et al.
Pediatrics 2012
Read Paper

Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy Adults
Negative study – bolus dosing and high starting vitamin D values
Murdoch et al.
JAMA 2012
Read Paper

Vitamin D3 supplementation in patients with frequent respiratory tract infections: A randomized and double-blind intervention study
Positive study – lower infection, daily dosing for one year
Bergman et al.
BMJ Open 2012
Read Paper

Important Message

NEWS ALERT: States, Governments Acknowledge the Need for Vitamin D to Build the Immune System; Vitamin D*action has achieved a major milestone of ‘Moving Research into PRACTICE’!

EVERYONE needs to know about the benefits of vitamin D... We need your help to do this. Donating $25.00 today will positively affect millions of lives!

We will take this opportunity to use our extensive network to get pertinent information on vitamin D to the new US COVID Panel as well as local and state government representatives around the world.

Donate $25 today to help support this outreach effort (and, let us know if your employer could match the donations made by individuals from now until January 1, 2021!). You can also "text-to-give" by simply texting Daction to 44321.

Donations made through GiveLively are received in full by GrassrootsHealth.

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!