Take Vitamin D*Action!

By Moving Vitamin D Research into Practice

Join scientists, healthcare practitioners, advocates, and individuals working together to advance Vitamin D knowledge, improve public health, and create measurable health outcomes worldwide.

🧮 Vitamin D*Calculator

Calculate your personal daily dose of vitamin D.

🩺 Your Risk of Deficiency

Take the quiz to see if you have a high risk of low vitamin D levels.

Join Our New Vitamin D*Community

A membership-based collaborative online community where researchers, practitioners, policy makers, advocates, and individuals can connect, learn, and take action.

Participants & Individuals

  • Ask questions
  • Learn from experts
  • Health topic communities
  • Live Webinars & Group Discussions

Practitioners

  • Practitioner support
  • Continuing education
  • Certification programs
  • Wholesale testing 

Scientists

  • Collaborate on studies
  • Access research groups
  • Share publications
  • Connect & innovate

Advocates & Leaders

  • Advocacy Support
  • Leadership Framework
  • Public Health & Policy Support
  • Team Spaces & Local Connection

Specials & Spotlights

GrassrootsHealth Testing Options

Optimize your health with accurate testing and personalized protocols.

D*action Study

Join the world's largest vitamin D research study while tracking your own vitamin D status.

Check Your D

Monitor your vitamin D level with a convenient home test kit—no study enrollment required.

Interested in measuring more than vitamin D?

How Vitamin D Changed the Life of a Doctor with MS – Her Journey and an Interview

The following is a narrative by Satya L. Nahu, MD. The Coimbra Protocol has helped thousands around the world overcome their autoimmune diseases using extremely high doses of vitamin D. Do not treat yourself without the guidance of a skilled practitioner…Read More

Satya L. Nahu, MD Participant

Disturbing Trends among Teenagers – How Nutrients CAN Help

“Mom… I feel like I’m dying.” The latest statistics show that almost 60% of teenage female students experienced persistent feelings of sadness or hopelessness and nearly 25% made a suicide plan. One mom’s story could help many others. Read More

Beth (North Dakota) Participant

Participant Story: Why I Keep My Vitamin D Above 100 ng/ml

The GrassrootsHealth panel of scientists recommends a vitamin D level between 40-60 ng/ml; what happens when higher levels are maintained? Bob is a long-time participant in the GrassrootsHealth D*action project who shares his story here. Read More

Bob Participant

Vitamin D Can Turn Your Health Around

Vitamin D has helped me to walk, to sleep, to get off medication; After many years of research and personal use of vitamin D, I strongly believe in the preventive and curative powers of vitamin D for cancer and other health problems. Read More

Zuleika Jamal Participant
Testimonials

Real People. Real Results.

Read inspiring stories from our community.

Our Mission

Eliminating Worldwide Vitamin D Deficiency and Its Health Consequences

GrassrootsHealth advances public health through research, education, testing, and community collaboration. Together with scientists, healthcare professionals, and individuals around the world, we are creating a future where evidence-based knowledge leads to healthier lives.

Our Experts

Meet the Vitamin D Scientists & Experts

The world’s leading vitamin D scientists and experts dedicated to advancing vitamin D research into public health and practice.

Cedric F. Garland, Dr.P.H., F.A.C.E.

Principal Investigator

William B. Grant, Ph.D.

Director & Senior Researcher

Michael F. Holick, Ph.D., M.D.

Vitamin D Researcher & Physician

Carol L. Wagner, M.D.

Pediatrician and Neonatologist

"Meet the distinguished scientists, physicians, and health experts whose research, expertise, and commitment are helping shape the future of Vitamin D education, prevention, and wellness across the globe."

Research Hub

Explore the Science Behind Better Health

Cancer Prevention with Vitamin D

The Vitamin D Deficiency Epidemic 40-75% of the entire world’s population is vitamin D deficient. The causal link between severe vitamin D deficiency and rickets

Learn More

Cancer Prevention and Vitamin D

Vitamin D Supplement Doses and Serum 25-Hydroxyvitamin D in the Range Associated with Cancer Prevention Cedric F. Garland, Christine B. French, Leo L. Baggerly, and

Learn More

Achievements Timeline

From running the world’s largest population field trial on vitamin D and contributing to groundbreaking nutrient research, to award-winning initiatives empowering individuals and health practitioners with education and evidence-based resources.

2007

GrassrootsHealth Founded

Founded by Carole Baggerly with the mission of moving vitamin D research into practice.

2008

D*action Study Begins

Enrollment opens and the first Scientists' Call to D*action is signed by 40 international vitamin D scientists.

2011

First Published Research

The first scientific paper using D*action study data is published.

2015

Prenatal Health Project

Large prenatal vitamin D project launches to improve prenatal & neonatal health.

2016

Humanitarian Award

GrassrootsHealth receives the American College of Nutrition Humanitarian Award.

2021

PLOS ONE Top 10% Paper

Our paper on breast cancer risk and vitamin D serum level is awarded the top 10% of 2018 papers published in PLOS ONE for being cited in other research

2018

National Recognition

Receives the NBJ Award for Excellence in Education and the Mercola Achievement Award.

2020

Top-Cited Vitamin D & COVID Paper

Publication of Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths, now the top-cited paper on vitamin D and COVID

2025

Capitol Hill Advocacy

GrassrootsHealth visits Capitol Hill in Washington DC to advocate for vitamin D and maternal health.

2023

Education Expansion

Launch of CEU-approved online course and Vitamin D Best Practices Toolkit.

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YEARS OF RESEARCH

Since 2007

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COUNTRIES

Represented

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STUDY PARTICIPANTS

And growing every day

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SCIENTIFIC EXPERTS

Worldwide collaborators

Blog

Latest News, Research & Insights

Stay informed with the latest Vitamin D research, scientific discoveries, health insights, and community updates from GrassrootsHealth and leading experts around the world.

Webinars, Events & Meetings

Webinars, Summits & Live Education

Join us to learn more from the experts, get your questions answered, hear the latest research, and collaborate with our advocacy and outreach teams.

20

May

Vitamin D & Diabetes Prevention: New Research Findings

Tuesday, May 20, 2005-100 PM ST

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June

Therapeutic Vitamin D for Practitioners

Tuesday, June 10,2025 12:00 PM

24

June

Researcher Roundtable: Global Collaboration

Tuesday, June 24, 2025, at 1:00 PM ET

Learn More About Vitamin D: Open Group Q&A

Free Webinar: Know Your “D” Number

Vitamin D Dosing Policy Update: An Expert Panel Discussion

Home Testing

GrassrootsHealth Testing Options

Optimize your health with accurate testing and personalized protocols.

Ask Sunny AI

Ask Sunny Anything About Vitamin D

Sunny Hippocrates is our Al assistant trained exclusively on Grassroots Health research, publications, FAQs, and resources.

Click Sunny in the lower right corner anytime to start a conversation! Sunny is always here to help.

Sponsors, Partners & Affiliates

Together we can advance public health with vitamin D.

Empowering Better Health Worldwide

Join the Global Vitamin D*Action Movement

Whether you’re a scientist, healthcare professional, advocate, or someone seeking better health, GrassrootsHealth provides the research, education, testing, and community to help you make informed decisions about vitamin D for yourself, your loved ones, and your patients.