The VITAL Trial Explained: What the Vitamin D Results Mean for US Supplement Makers

What was the VITAL trial?

VITAL (the VITamin D and OmegA-3 TriaL) was a nationwide, randomised, placebo-controlled trial with a two-by-two factorial design. It enrolled US men aged 50 or older and women aged 55 or older who had no cancer or cardiovascular disease at entry, and tested vitamin D3 (cholecalciferol) at 2,000 IU a day and marine omega-3 fatty acids at 1 g a day. In all, 25,871 people were randomised, including 5,106 Black participants.^[1] This article covers the vitamin D comparison only.

The dose of 2,000 IU (50 mcg) a day is above the US Recommended Dietary Allowance of 600 IU for ages 1 to 70 and 800 IU for ages 71 and older, and half the adult Tolerable Upper Intake Level of 4,000 IU.^[8] Participants were not selected for deficiency. Among the 15,787 with an analysable baseline blood sample, mean serum 25-hydroxyvitamin D (25(OH)D) was 30.8 ng/mL (SD 10.0), and 12.7% were below 20 ng/mL.^[1] The Institute of Medicine treats 20 ng/mL as the level that meets the needs of at least 97.5% of the population,^[8] so most VITAL participants started with adequate vitamin D status.

How the evidence was gathered

VITAL had two primary end points: invasive cancer of any type, and major cardiovascular events (a composite of myocardial infarction, stroke and death from cardiovascular causes). Site-specific cancers, death from cancer and other cardiovascular events were secondary end points. Median follow-up was 5.3 years.^[1]

Every participant completed a three-month placebo run-in and agreed to keep vitamin D from all other supplements, including multivitamins, to 800 IU a day or less. To confirm exposure, the investigators re-measured blood levels in a subset of 1,644 participants: mean 25(OH)D rose from 29.8 ng/mL to 41.8 ng/mL after one year on vitamin D3, a 40% increase, and barely changed on placebo.^[1]

What the primary results showed

Vitamin D3 did not lower the risk of either primary end point. Invasive cancer was diagnosed in 1,617 participants (793 on vitamin D, 824 on placebo) and a major cardiovascular event occurred in 805 (396 vs 409).^[1] Myocardial infarction, stroke, cardiovascular death and all-cause death were also unchanged, and there was no excess of hypercalcaemia, kidney stones or gastrointestinal symptoms.^[1]

So does vitamin D prevent cancer or heart disease in this trial? Not for total incidence, and not for heart attack, stroke or cardiovascular death.

Table 1. VITAL main results, vitamin D3 2,000 IU a day vs placebo^[1]

The signals that still matter: cancer death and body weight

The signal most often quoted is cancer mortality. Overall it was not significant (HR 0.83), but when the first two years of follow-up were excluded the hazard ratio was 0.75, with 112 deaths on vitamin D against 149 on placebo. That analysis was not specified in the trial protocol, and the authors caution that secondary analyses were not adjusted for multiple comparisons, so it generates a hypothesis rather than settling one.^[1]

A later secondary analysis looked at advanced (metastatic or fatal) cancer and found fewer cases on vitamin D: 226 of 12,927 against 274 of 12,944 (HR 0.83, 95% CI 0.69–0.99). The effect was confined to people with a body mass index (BMI) under 25 (HR 0.62, 0.45–0.86), with no reduction at BMI 25 to under 30 (HR 0.89, 0.68–1.17) or 30 and above (HR 1.05, 0.74–1.49).^[4]

One proposed explanation is exposure. In more than 16,000 VITAL participants, baseline 25(OH)D was 32.3 ng/mL at normal weight and fell stepwise to 28.0 ng/mL in class II obesity, and the rise in vitamin D biomarkers after two years of supplementation was significantly smaller at higher BMI.^[5] The authors present this as a possible partial explanation, not proof of a weight-specific benefit.

What the ancillary VITAL analyses add

Investigators have used the same randomised population to test many other outcomes. Most echo the main result; one, autoimmune disease, points the other way. Each comes from a separate paper with its own primary end point, follow-up and subgroups.

Table 2. Selected VITAL ancillary results for vitamin D3 2,000 IU a day

Two details matter when these papers are quoted. The type 2 diabetes paper also pooled VITAL with three earlier trials and found a modest reduction (HR 0.89, 0.80–0.99), but VITAL on its own was null.^[12] The telomere and anaemia findings come from small sub-cohorts and measure biomarkers rather than disease.^[14][15]

What the VITAL trial vitamin D data do and do not support

The VITAL trial vitamin D results support two plain statements. Daily vitamin D3 at 2,000 IU raised blood 25(OH)D, and it did not reduce invasive cancer or major cardiovascular events in a largely vitamin D-replete, older US population.^[1] A 2025 commentary in the Journal of Bone and Mineral Research cites VITAL as showing no benefit for cancer, cardiovascular disease, bone density and fractures in that population.^[6]

A 2023 review of large randomised trials and Mendelian randomisation studies reached a similar view: supplementation did not reduce bone loss, fractures, falls, cancer incidence or cardiovascular risk in generally healthy people, while trials and meta-analyses suggest a possible effect on cancer mortality. The authors stress that these findings come from mostly replete populations and do not apply to adults with deficiency or osteoporosis.^[7]

The 2024 Endocrine Society guideline, which drew heavily on trials such as VITAL, suggests against empiric vitamin D above the Dietary Reference Intakes to lower disease risk in healthy adults younger than 75, and against routine 25(OH)D testing. It does suggest empiric supplementation for children and adolescents, adults over 75, pregnancy and high-risk prediabetes.^[16]

Implications for supplement claims

Structure/function vs disease claims

A structure/function claim describes the role of a nutrient in the normal structure or function of the body. The manufacturer must hold substantiation that it is truthful and not misleading, notify the FDA no later than 30 days after first marketing the product with the claim,^[10] and carry the disclaimer that the statement has not been evaluated by the FDA and the product is not intended to diagnose, treat, cure or prevent any disease.^[9]

A claim that a supplement prevents cancer or heart disease is a disease claim; it is outside the structure/function route and would subject the product to regulation as a drug.^[9] The one disease-related claim open to vitamin D is the authorised health claim for calcium and vitamin D and osteoporosis, which has its own conditions, including a “high” level of calcium and, to name vitamin D, a “high” level of vitamin D.^[17] Label rules, % Daily Value and the disclaimer are covered in our guide to FDA rules for vitamin D supplements.

Table 3. What each evidence area allows on a US supplement label

How makers should frame vitamin D evidence

For nutraceutical product development, VITAL works best as a boundary, not a selling point. It shows what 2,000 IU a day achieved in blood terms and where disease end points did not move. Record the dose, form, population, end point and whether the analysis was primary, secondary or post hoc beside every result you cite in a claims dossier.

Three practical points follow. First, the tested dose is a design input, not a claim: a 50 mcg (2,000 IU) product can describe its vitamin D content, but its wording should stay away from VITAL’s cancer and cardiovascular end points. Second, because the 25(OH)D response was smaller at higher BMI,^[5] one strength may not suit every consumer group, which is a positioning question rather than a claim. Third, the label amount is a floor that the product must meet through its shelf life; how much overage that needs is covered in our vitamin D overage guide.

Format changes the picture too. A vitamin D gummy has different overage and stability needs from a softgel, as our gummy supplement formulation guide explains, and a vitamin D drink sold as a conventional food rather than a supplement follows different claim rules, covered in our functional beverage FDA regulations Q&A.

Limitations and research gaps

• VITAL enrolled older, mostly vitamin D-replete adults; it did not test supplementation in people with deficiency.^[1][7]
• Participants could take up to 800 IU a day of vitamin D outside the trial, which narrows the contrast between the arms.^[1]
• Median treatment was 5.3 years, which may be short for cancer outcomes.^[1]
• The cancer-death and BMI findings are secondary or post hoc and were not adjusted for multiple comparisons.^[1][4]
• Only one dose and one form (D3, 2,000 IU daily) were tested.^[1]
• Some ancillary papers rely on sub-cohorts of a few hundred to a few thousand people.^[14][15]

Conclusion

The VITAL trial vitamin D results are best used as an evidence boundary. Vitamin D3 at 2,000 IU a day raised serum 25(OH)D, but invasive cancer, major cardiovascular events, fractures, respiratory infection, type 2 diabetes and atrial fibrillation did not fall in a largely replete older population.^{[1][2][11][12][13]} The autoimmune and cancer-death signals are worth watching, not claiming. For a US supplement maker, that means status and role-of-nutrient wording, a substantiation file that records exactly what each study tested, and no disease-prevention language.

For brands & formulators

Food Research Lab helps US supplement brands turn evidence like VITAL into a product and a label that hold up. Our nutraceutical product development team covers formulation, dose and form selection, stability and overage planning, and claim substantiation files, and our regulatory and scientific research team reviews Supplement Facts panels and structure/function wording against current FDA rules. We work from Chennai, India, for brands selling in the US.

Analytical work such as vitamin D3 assay, dissolution and stability testing is run or arranged through accredited partner laboratories. Share your formula, target claims and market through our contact page.

In this series

This article opens FRL’s series on developing vitamin D supplements for the US market.

• The VITAL trial explained (you are here): what the vitamin D results show and what they allow on a label.
• FDA rules for vitamin D supplements: Supplement Facts, mcg and IU, % Daily Value, tolerances, claims and cGMP.
• Vitamin D overage in supplements: the hub guide to setting overage so the label claim holds through shelf life.
• Vitamin D3 dissolution testing: inside the lab on how release is tested.
• Vitamin D3 supplement development: a worked example from brief to launch-ready product.
• Nutraceutical product development service: formulation, testing and regulatory support with FRL.

1. Manson, J. E., Cook, N. R., Lee, I.-M., Christen, W., Bassuk, S. S., Mora, S., … Buring, J. E., for the VITAL Research Group. (2019). Vitamin D supplements and prevention of cancer and cardiovascular disease. New England Journal of Medicine, 380(1), 33–44. https://doi.org/10.1056/NEJMoa1809944 (cited for design, population, baseline and one-year 25(OH)D, primary and secondary results, the post hoc two-year exclusion analysis and adverse events).
2. LeBoff, M. S., Chou, S. H., Ratliff, K. A., Cook, N. R., Khurana, B., Kim, E., … Manson, J. E. (2022). Supplemental vitamin D and incident fractures in midlife and older adults. New England Journal of Medicine, 387(4), 299–309. https://doi.org/10.1056/NEJMoa2202106 (cited for total, non-vertebral and hip fracture results).
3. Hahn, J., Cook, N. R., Alexander, E. K., Friedman, S., Walter, J., Bubes, V., … Costenbader, K. H. (2022). Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial. BMJ, 376, e066452. https://doi.org/10.1136/bmj-2021-066452 (cited for the autoimmune disease result (HR 0.78, P = 0.05)).
4. Chandler, P. D., Chen, W. Y., Ajala, O. N., Hazra, A., Cook, N., Bubes, V., … Manson, J. E. (2020). Effect of vitamin D3 supplements on development of advanced cancer: A secondary analysis of the VITAL randomized clinical trial. JAMA Network Open, 3(11), e2025850. https://doi.org/10.1001/jamanetworkopen.2020.25850 (cited for advanced cancer overall and by BMI category).
5. Tobias, D. K., Luttmann-Gibson, H., Mora, S., Danik, J., Bubes, V., Copeland, T., … Manson, J. E. (2023). Association of body weight with response to vitamin D supplementation and metabolism. JAMA Network Open, 6(1), e2250681. https://doi.org/10.1001/jamanetworkopen.2022.50681 (cited for baseline 25(OH)D by BMI category and the blunted response at higher BMI).
6. Gordon, C. M., & LeBoff, M. S. (2025). Vitamin D and disease prevention in 2024: Commentary on recent Endocrine Society recommendations. Journal of Bone and Mineral Research, 40(5), 569–571. https://doi.org/10.1093/jbmr/zjaf036 (cited for the reading of VITAL as showing no benefit for cancer, cardiovascular disease, bone density and fractures).
7. Bouillon, R., LeBoff, M. S., & Neale, R. E. (2023). Health effects of vitamin D supplementation: Lessons learned from randomized controlled trials and Mendelian randomization studies. Journal of Bone and Mineral Research, 38(10), 1391–1403. https://doi.org/10.1002/jbmr.4888 (cited for the summary of large trials and the caveat that findings in replete populations do not apply to deficient adults).
8. Ross, A. C., Manson, J. E., Abrams, S. A., Aloia, J. F., Brannon, P. M., Clinton, S. K., … Shapses, S. A. (2011). The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: What clinicians need to know. Journal of Clinical Endocrinology & Metabolism, 96(1), 53–58. https://doi.org/10.1210/jc.2010-2704 (cited for the RDAs of 600 and 800 IU, the 4,000 IU upper level and the 20 ng/mL level).
9. U.S. Food and Drug Administration. (2026). 21 CFR 101.93: Certain types of statements for dietary supplements. Electronic Code of Federal Regulations, current as of 6 November 2026. https://www.ecfr.gov/current/title-21/section-101.93 (cited for notification, the disclaimer text and the structure/function vs disease claim boundary).
10. U.S. Food and Drug Administration. (2024). Structure/function claims. https://www.fda.gov/food/nutrition-food-labeling-and-critical-foods/structurefunction-claims (cited for substantiation and notification no later than 30 days after marketing).
11. Camargo, C. A., Jr., Schaumberg, D. A., Friedenberg, G., Dushkes, R., Glynn, R. J., Gold, D. R., … Manson, J. E. (2024). Effect of daily vitamin D supplementation on risk of upper respiratory infection in older adults: A randomized controlled trial. Clinical Infectious Diseases, 78(5), 1162–1169. https://doi.org/10.1093/cid/ciad770 (cited for the upper respiratory infection result).
12. Tobias, D. K., Pradhan, A. D., Duran, E. K., Li, C., Song, Y., Buring, J. E., Cook, N. R., Mora, S., & Manson, J. E. (2025). Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial. Nature Communications, 16, 3332. https://doi.org/10.1038/s41467-025-58721-6 (cited for the type 2 diabetes result and the four-trial meta-analysis).
13. Albert, C. M., Cook, N. R., Pester, J., Moorthy, M. V., Ridge, C., Danik, J. S., … Manson, J. E. (2021). Effect of marine omega-3 fatty acid and vitamin D supplementation on incident atrial fibrillation: A randomized clinical trial. JAMA, 325(11), 1061–1073. https://doi.org/10.1001/jama.2021.1489 (cited for the VITAL Rhythm atrial fibrillation result).
14. Cho, H. L., Li, C., Manson, J. E., Cook, N. R., Lee, I.-M., Buring, J. E., & Berliner, N. (2025). Effect of vitamin D and omega-3 fatty acid supplementation on anemia incidence among older adults: The VITAL trial. Blood Red Cells & Iron, 1(3), 100032. https://doi.org/10.1016/j.brci.2025.100032 (cited for the anaemia result in the 839-person sub-cohort).
15. Zhu, H., Manson, J. E., Cook, N. R., Bekele, B. B., Chen, L., Kane, K. J., … Dong, Y. (2025). Vitamin D3 and marine ω-3 fatty acids supplementation and leukocyte telomere length: 4-year findings from the VITamin D and OmegA-3 TriaL (VITAL) randomized controlled trial. American Journal of Clinical Nutrition, 122(1), 39–47. https://doi.org/10.1016/j.ajcnut.2025.05.003 (cited for the telomere attrition result).
16. Demay, M. B., Pittas, A. G., Bikle, D. D., Diab, D. L., Kiely, M. E., Lazaretti-Castro, M., … McCartney, C. R. (2024). Vitamin D for the prevention of disease: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism, 109(8), 1907–1947. https://doi.org/10.1210/clinem/dgae290 (cited for the 2024 recommendations on empiric supplementation and testing).
17. U.S. Food and Drug Administration. (2026). 21 CFR 101.72: Health claims: calcium, vitamin D, and osteoporosis. Electronic Code of Federal Regulations, current as of 6 November 2026. https://www.ecfr.gov/current/title-21/section-101.72 (cited for the conditions of the authorised calcium and vitamin D health claim).