Vitamin D and Your Health
How Much Do You Need?
Back in 2009, health magazines filled their pages with vitamin D articles. Supplement companies pushed high doses. The message was simple: everyone needs more. In 2025, we have better data. The picture is more nuanced than the headlines suggested.
What is vitamin D?
Vitamin D is a fat-soluble vitamin. Few foods contain it naturally. Food manufacturers add it to milk, cereals, and other products. You can also take it as a supplement.
Vitamin D helps your gut absorb calcium. Without enough, your bones weaken. In children, severe deficiency causes rickets. In adults, bones become brittle and prone to fracture.
Your body makes vitamin D when sunlight hits your skin. People call it the sunshine vitamin. You also get it from fatty fish, egg yolks, and fortified milk and cereals.
Vitamin D and Disease
In the 1920s, rickets was widespread among children. Their bones grew soft and deformed.
To combat rickets, manufacturers added vitamin D to milk in the 1930s and 1940s. Milk consumption rose from 34 gallons per person in 1909 to 45 gallons by 1945. Rickets virtually disappeared as a public health concern.
Then things changed.
Milk consumption dropped as soft drinks gained popularity and people worried about fat and cholesterol. By 2001, Americans drank just 23 gallons per year, half the 1945 peak.
At the same time, concerns about skin cancer prompted more people to avoid sun exposure and use sunscreen. Less sun meant less vitamin D production in the skin.
Weight trends made things worse. Obesity lowers measured vitamin D levels through dilution and storage in fat tissue. More than 40 percent of American adults are currently obese. Vitamin D insufficiency has become more common.
These trends created an opening. For years, supplement companies promoted vitamin D with claims that went beyond the evidence. Some of those claims have stuck around even as research has clarified what works and what does not.
Here are four persistent myths about vitamin D.
Myth 1: Everybody would benefit from taking a vitamin D supplement.
The supplement industry wants you to believe everyone needs extra vitamin D. The evidence shows otherwise.
Most healthy adults need 600 IU daily until age 70, then 800 IU after that. You get this primarily from fortified foods and supplements when needed.
Vitamin D is added to milk, orange juice, breakfast cereals, and some plant milks. Check the nutrition label. A cup of fortified milk provides about 100 IU. A cup of fortified orange juice provides about 100 IU. Many cereals provide 40 to 80 IU per serving. Three servings of fortified foods give you half your daily needs.
Add fatty fish twice a week, and most people meet the target without extra supplements.
Sun exposure contributes some vitamin D, but the amount varies widely based on your skin tone, geographic location, season, time of day, age, clothing, and sunscreen use. In northern locations during winter months, your skin makes almost no vitamin D regardless of time spent outdoors. Because sun exposure is unreliable and increases skin cancer risk, dermatology groups recommend getting vitamin D from food and supplements rather than intentional sun exposure.
The 2024 Endocrine Society guideline recommends meeting the Dietary Reference Intakes (600 IU daily until age 70, then 800 IU) through diet or supplements if needed. Routine high-dose supplementation isn’t advised for healthy adults under 75, and routine blood testing isn’t required unless you have risk factors.
Some groups may need higher amounts based on individual circumstances.
- Breastfed infants without supplementation face a higher risk of deficiency and rickets.
- Children and adolescents may benefit from higher intake to support bone growth and reduce respiratory infections.
- Pregnant people may benefit from higher intake to reduce pregnancy complications.
- Adults over 75 may benefit from a higher intake to reduce mortality risk.
- People with prediabetes may benefit from a higher intake to slow progression to diabetes.
- People with obesity, dark skin, malabsorption disorders, or limited sun exposure also face a higher risk of insufficiency.
If any of these situations apply to you, talk with your doctor about testing and supplementation. The decision depends on your current vitamin D status, diet, lifestyle, and health conditions. Most healthy adults without these risk factors get enough from fortified foods without extra supplements.
Myth 2: Just sitting in the sun for a few minutes every day will give you all the vitamin D you need.
Sun exposure is unreliable and risky. Don’t count on it.
Your body makes vitamin D when ultraviolet B rays penetrate your skin. How much you make depends on multiple factors.
- Skin tone matters most. Lighter skin synthesizes vitamin D more efficiently because less melanin blocks the UV rays. Darker skin requires longer exposure to produce the same amount.
- Geography and season change production. UV rays are stronger near the equator. In northern latitudes, winter sun sits too low in the sky for your skin to make much vitamin D. From November through February in places like Boston or Seattle, you make almost none.
- Age reduces synthesis. Older skin makes 75 percent less vitamin D than younger skin from the same sun exposure.
- Obesity lowers measured vitamin D levels through dilution and storage in fat tissue. Having a body mass index over 30 increases your risk of insufficiency.
- Sunscreen blocks production. SPF 30 reduces synthesis by more than 95 percent.
- Smoking and certain medications also interfere with production and metabolism.
Dermatology groups say do not skip sunscreen to raise your vitamin D. Get vitamin D from food and supplements instead. Skin cancer risk outweighs any vitamin D benefit from unprotected exposure.
If you avoid fortified foods, have dark skin, live at northern latitudes, or are obese, you need supplements to meet your requirements. Sun exposure alone will not cover you.
Myth 3: Vitamin D reverses osteoporosis and can reduce your risk of cancer.
The bone claims are oversold. The cancer claims are mixed.
Start with bones. Vitamin D prevents rickets in children and osteomalacia in adults when deficiency exists. The evidence is clear on this.
For osteoporosis prevention in healthy adults, the data are weaker. Large trials show vitamin D alone does not prevent fractures or falls in community-dwelling older adults who meet basic intake levels.
The 2024 U.S. Preventive Services Task Force draft recommendation advises against taking vitamin D supplements to prevent fractures or falls if you live independently and do not have a deficiency.
Calcium plus vitamin D supplementation lowers fracture risk in older adults in institutional care settings like nursing homes. The combination shows little benefit for healthy adults living independently.
Vitamin D does not reverse osteoporosis. If you take medication for bone disease, your doctor will prescribe vitamin D and calcium together as part of your treatment plan.
Now cancer. Large randomized trials show that daily vitamin D supplementation does not reduce cancer incidence in adults who already meet basic vitamin D needs. You do not prevent cancer by taking vitamin D.
The mortality picture is less clear. Meta-analyses of randomized trials testing doses around 2,000 IU daily found vitamin D reduced cancer deaths by about 10 to 15 percent. Other analyses found no effect. The data conflict.
The benefit, if real, appears modest and uncertain. It requires daily dosing over years. More research is needed to confirm whether vitamin D actually reduces cancer mortality.
Myth 4: Vitamin D supplements are completely safe.
Vitamin D supplements are safe at recommended doses. They become dangerous at very high doses.
The tolerable upper limit for adults is 4,000 IU daily from all sources. This is the highest amount most people can take long-term without risk of harm. Stay under this limit unless your doctor prescribes higher amounts for treatment.
Current recommendations from the National Academies say most people need 600 IU daily until age 70, then 800 IU after that. These amounts are well below the safety threshold.
Toxicity is rare. It occurs when prolonged high dosing drives your blood level well above safe ranges and causes high blood calcium. Most experts consider 20–30 ng/mL adequate. Levels above 50 ng/mL can signal excess. Toxicity with severe symptoms typically occurs at much higher levels. Most documented cases involve doses far exceeding 10,000 IU daily taken for months or years.
Symptoms start with loss of appetite, nausea, and vomiting. As calcium builds up in your blood, you develop weakness, confusion, and excessive thirst. Severe cases cause kidney damage, irregular heartbeat, and calcium deposits in your arteries and soft tissues.
Toxicity almost always comes from supplements, not food or sun. Manufacturing errors have caused problems when products contained thousands of times more vitamin D than listed on the label.
Some medications interact with vitamin D. Thiazide diuretics combined with high-dose vitamin D raise your risk of dangerously high calcium levels.
People with kidney disease, hyperparathyroidism, or granulomatous disorders should take vitamin D only under medical supervision. These conditions change how your body processes calcium and increase the risk of toxicity even at moderate doses.
The Bottom Line:
Most healthy adults under 75 get enough vitamin D from fortified foods and modest sun exposure. Follow the recommended intakes: 600 IU daily until age 70, then 800 IU after that.
Some groups may need higher amounts, including children, pregnant people, adults over 75, and people with prediabetes. If you fall into one of these groups, talk with your doctor about supplementation.
Get tested if you have limited sun exposure, dark skin, obesity, malabsorption disorders, or take certain medications. Testing makes sense for people with risk factors, but it is not recommended as routine screening.
Optimal doses for these groups remain uncertain. Talk with your clinician about the right amount for your situation. Stay under 4,000 IU daily unless your doctor recommends higher amounts for treatment. Choose daily doses over large intermittent doses.
More is not always better. Target your vitamin D intake to your actual needs.
For more details on Vitamin D, we recommend these two videos by NutritionFacts.org.
About Vitamin D Testing:
The 2024 Endocrine Society guidelines recommend against routine vitamin D testing for healthy adults. Testing makes sense only if you have risk factors like limited sun exposure, dark skin, obesity, malabsorption disorders, or certain medications.
If you do get tested, the 25-hydroxyvitamin D test measures your status. Most experts consider levels at or above 20 ng/mL sufficient for bone health. Levels below 12 ng/mL indicate deficiency with risk for rickets or osteomalacia. Levels above 50 ng/mL raise concerns about potential harm.
Lab results vary depending on the testing method used. Experts disagree on what level is optimal beyond basic bone health. Your doctor considers your individual situation, not just a single number.
Don't request testing just to check your levels. Focus on meeting the recommended dietary intakes for your age group.
Reference Links:
Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline
Marie B. Demay (Chair), Anastassios G. Pittas (Co-Chair), Daniel D. Bikle, Dima L. Diab, Mairead E. Kiely, Marise Lazaretti-Castro, Paul Lips, Deborah M. Mitchell, M. Hassan Murad, Shelley Powers, Sudhaker D. Rao, Robert Scragg, John A. Tayek, Amy M. Valent, Judith M. E. Walsh, Christopher R. McCartney
The Journal of Clinical Endocrinology & Metabolism, Published August 2024 (online June 2024)
Click Here for the Study: https://www.endocrine.org/clinical-practice-guidelines/vitamin-d-for-prevention-of-disease
Vitamin D - Fact Sheet for Health Professionals
National Institutes of Health Office of Dietary Supplements, Published Update June 27, 2025
Click Here for the Study: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Vitamin D Deficiency
Jasleen Kaur, Swapnil Khare, Omeed Sizar, Amy Givler
StatPearls Publishing, Last Update: February 15, 2025
Click Here for the Study: https://www.ncbi.nlm.nih.gov/books/NBK532266/
Association of Body Weight With Response to Vitamin D Supplementation and Metabolism
Deirdre K. Tobias, JoAnn E. Manson, and the VITAL Research Group
JAMA Network Open, Published January 17, 2023
Click Here for the Study: https://doi.org/10.1001/jamanetworkopen.2022.50681
Vitamin D, Calcium, or Combined Supplementation for the Primary Prevention of Fractures in Community-Dwelling Adults
US Preventive Services Task Force Recommendation Statement, Published Online: April 17, 2018
Click Here for the Study: https://doi.org/10.1001/jama.2018.3185
Efficacy of vitamin D3 supplementation on cancer mortality: Systematic review and individual patient data meta-analysis of randomised controlled trials
Sabine Kuznia, Anna Zhu, Taisuke Akutsu, Julie E. Buring, Carlos A. Camargo Jr, Nancy R. Cook, Li-Ju Chen a, Ting-Yuan David Cheng, Sari Hantunen, I.-Min Lee, JoAnn E. Manson, Rachel E. Neale, Robert Scragg, Aladdin H. Shadyab, Sha Sha, John Sluyter, Tomi-Pekka Tuomainen, Mitsuyoshi Urashima, Jyrki K. Virtanen, Ari Voutilainen, Jean Wactawski-Wende, Mary Waterhouse, Hermann Brenner, Ben Schöttker
Ageing Research Reviews, Published Volume 87, June 2023, 101923
Click Here for the Study: https://doi.org/10.1016/j.arr.2023.101923
Effect of Vitamin D3 Supplements on Development of Advanced Cancer - A Secondary Analysis of the VITAL Randomized Clinical Trial
Paulette D Chandler, Wendy Y Chen, Oluremi N Ajala, Aditi Hazra, Nancy Cook, Vadim Bubes, I-Min Lee, Edward L Giovannucci, Walter Willett, Julie E Buring, JoAnn E Manson; VITAL Research Group
JAMA Network Open, Published Online: November 18, 2020
Click Here for the Study: https://doi.org/10.1001/jamanetworkopen.2020.25850
Effects of Supplemental Vitamin D on Bone Health Outcomes in Women and Men in the VITamin D and OmegA‐3 TriaL (VITAL)
Meryl S LeBoff, Sharon H Chou, Elle M Murata, Catherine M Donlon, Nancy R Cook, Samia Mora, I‐Min Lee, Gregory Kotler, Vadim Bubes, Julie E Buring, JoAnn E Manson
Journal of Bone and Mineral Research, Published Volume 35, Issue 5, 1 May 2020
Click Here for the Study: https://doi.org/10.1002/jbmr.3958
Vitamin D and Calcium in Osteoporosis, and the Role of Bone Turnover Markers: A Narrative Review of Recent Data from RCTs
Gavriela Voulgaridou, Sousana K Papadopoulou, Paraskevi Detopoulou, Despoina Tsoumana, Constantinos Giaginis, Foivi S Kondyli, Evgenia Lymperaki, Agathi Pritsa
Diseases, Published 2023 Feb 8
Click Here for the Study: https://doi.org/10.3390/diseases11010029
Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults
Meryl S. LeBoff, M.D., Sharon H. Chou, M.D., Kristin A. Ratliff, B.A., Nancy R. Cook, Sc.D., Bharti Khurana, M.D., Eunjung Kim, M.S., Peggy M. Cawthon, Ph.D., M.P.H., Douglas C. Bauer, M.D., Dennis Black, Ph.D., J. Chris Gallagher, M.D., I-Min Lee, M.B., B.S., Sc.D., Julie E. Buring, Sc.D., and JoAnn E. Manson, M.D., Dr.P.H.
The New England Journal of Medicine, Published July 28, 2022
Click Here for the Study: https://www.nejm.org/doi/full/10.1056/NEJMoa2202106
Effect of monthly high-dose vitamin D supplementation on falls and non-vertebral fractures: secondary and post-hoc outcomes from the randomised, double-blind, placebo-controlled ViDA trial
Kay-Tee Khaw, Alistair W Stewart, Debbie Waayer, Carlene M M Lawes, Les Toop, Carlos A Camargo Jr, Robert Scragg
The Lancet Diabetes & Endocrinology, Epub 2017 Apr 28
Click Here for the Study: https://doi.org/10.1016/s2213-8587(17)30103-1
Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women
Jenna R Chalcraft, Linda M Cardinal, Perry J Wechsler, Bruce W Hollis, Kenneth G Gerow, Brenda M Alexander, Jill F Keith, D Enette Larson-Meyer
Nutrients, Published 2020 Jul 27
Click Here for the Study: https://doi.org/10.3390/nu12082237
Effect of High-Dose Vitamin D Supplementation on Volumetric Bone Density and Bone Strength - A Randomized Clinical Trial
Lauren A. Burt, Emma O. Billington, Marianne S. Rose, Duncan A. Raymond, David A. Hanley, Steven K. Boyd
JAMA Network, Published Online: August 27, 2019
Click Here for the Study: https://doi.org/10.1001/jama.2019.11889
Vitamin D Toxicity–A Clinical Perspective
Ewa Marcinowska-Suchowierska, Małgorzata Kupisz-Urbańska, Jacek Łukaszkiewicz, Paweł Płudowski, Glenville Jones
Frontiers in Endocrinology, Published 2018 Sep 20
Click Here for the Study: https://doi.org/10.3389/fendo.2018.00550
The D-Health Trial: a randomised controlled trial of the effect of vitamin D on mortality
Prof Rachel E Neale, PhDa, ∙ Catherine Baxter, BA ∙ Briony Duarte Romero, BA ∙ Donald S A McLeod, PhD, ∙ Prof Dallas R English, PhDd, ∙ Prof Bruce K Armstrong, D Philf, ∙ Prof Peter R Ebeling, MD ∙ Gunter Hartel, PhD ∙ Prof Michael G Kimlin, PhD ∙ Rachel O'Connell, PhD ∙ Jolieke C van der Pols, PhD ∙ Prof Alison J Venn, PhD ∙ Prof Penelope M Webb, D Phil, ∙ Prof David C Whiteman, PhD, ∙ Mary Waterhouse, PhD
The Lancet Diabetes & Endocrinology, Published February 2022
Click Here for the Study: https://doi.org/10.1016/s2213-8587(21)00345-4
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