Published on August 2, 2021

Our paper on breast cancer and vitamin D has been named as one of the top 10% most cited PLOS ONE papers published in 2018!

Exciting news!! Our paper, titled Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥ 60 vs < 20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort, is among the top 10% of 2018 papers published in PLOS ONE for being cited in other research.

Download the Paper

What Did This Paper Look At?

The study pooled and analyzed data from two randomized controlled trials (RCTs), led by Dr. Joan Lappe at Creighton University (2007, N=1129 and 2016, N=2196), combined with data from the GrassrootsHealth Breast Cancer Prevention Study cohort (N=1713). This analysis aimed to investigate the relationship between vitamin D level and breast cancer risk across a broad range of vitamin D concentrations among women aged 55 years or older.

The first RCT was published in 2007 and is summarized in our blog here. This study followed 1,179 healthy, postmenopausal women, aged 55 or older for four years and put them in one of three groups – taking a daily dose of 1,100 IU vitamin D and 1,400-1,500 mg calcium; calcium only; or placebo only. The study found that the vitamin D and calcium group had a 77% reduced risk of cancer as compared to the placebo group.

The second RCT focused solely on cancer. The 2,303 women enrolled in this study received either 2,000 IU/day of vitamin D and 1,500 mg/day of calcium or placebo. This study found a 30% reduction in cancer incidence with the vitamin D + calcium group, as compared to the placebo group. (paper here, blog here)

The third set of women comes from the GrassrootsHealth Breast Cancer Prevention Project. This group of women self-select to be in the study. To match the entry requirements of the RCTs, data from women aged 55 or older with no current cancer and not in treatment for cancer were included. They are asked to conduct an at-home blood test every six months (they prick their finger and drop blood on a special card) and answer a health questionnaire. At the time of this paper, there were 1,713 women enrolled whose data could be included in the analysis.

What were the Findings of this Paper?

Within the pooled cohort (N=5038), 77 women were diagnosed with breast cancer during the observation periods (median follow-up time: 4.0 years) with an age-adjusted incidence of 512 cases per 100,000 person-years. Comparing incidence rates of breast cancer by vitamin D level showed an 82% lower rate for women with 25(OH)D concentrations of at least 60 ng/ml (150 nmol/L) compared to less than 20 ng/ml (50 nmol/L; P = 0.006).

Click to Enlarge & Print

As you can see, vitamin D levels have a significant correlation with breast cancer incidence. The horizontal, or x-axis, records increasing vitamin D levels, from 0 to 100 ng/ml (250 nmol/L). Keep in mind that the average vitamin D level for all women in the US is 29 ng/ml, for African Americans, 21 ng/ml.

The vertical axis on the left-hand side shows the number of people in the blue bars that fall into each 10-ng/ml block of vitamin D levels. The white dots represent breast cancer occurrence; note that most of the dots (69%) are below 40 ng/ml (100 nmol/L), and very rarely above 60 ng/ml (150 nmol/L).

What Makes this Research Unique?

A big difference in this research is that the analysis assessed breast cancer risk across a broad range of vitamin D levels, including levels higher than 40 ng/ml (most previous studies focused on the lower ranges).

Also, most vitamin D clinical trials are designed and interpreted by assigned treatment dose, not by blood levels of vitamin D. Not all people react the same to a specific dosage nor does this capture vitamin D from the sun, food and personal supplements. Therefore, it is better to report on blood levels achieved, than the dosage given.

Download the Paper

Measure Your Level of Vitamin D and Other Important Nutrients

Having and maintaining healthy vitamin D levels and other nutrient levels can help improve your health now and for your future. Choose which to measure, such as your vitamin D, 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.

Help everyone Move Research into Practice with vitamin D and other nutrients! As a special birthday gift to everyone, in honor of the science, we have created a special scholarship fund for anyone to donate to that will go towards helping others participate. Your donation will allow anyone to get help with funding their participation when they need it.

Text-to-give: Text Daction to 44321 to add to our Scholarship Fund.

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!