Massive study tests if daily pills can ward off cancer and heart attacks
NCT ID NCT01169259
First seen Jun 25, 2026 · Last updated Jul 31, 2026 · Updated 3 times
Summary
This large study tested whether taking daily vitamin D3 and omega-3 (fish oil) supplements can lower the risk of developing cancer, heart disease, or stroke. Over 25,000 healthy older adults (men 50+, women 55+) took the supplements or placebos for about 5 years. The goal is to see if these common supplements can prevent serious illnesses in people without a prior history.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- vitamin D3 (cholecalciferol) and omega-3 fatty acids (fish oil)
- What this could lead to
- If it works, this could show that simple daily supplements help prevent cancer and heart disease in healthy older adults.
- What could go wrong
- This is a large, completed phase 3 trial, but results may show no benefit or only modest effects. Supplements are not a substitute for other healthy habits.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Phase 3
Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.
- Participants
-
25,871 people
The number who actually took part.
- Started
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Jul 2010
- Expected to finish
-
Oct 2026
An estimate. End dates often move.
- Lead sponsor
-
Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
50 years and older
- Sex
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Anyone
- Healthy volunteers
-
Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
To be eligible for the study, respondents had to, at study entry,: 1. be men aged 50 or older or women aged 55 or older; 2. have no history of cancer (except non-melanoma skin cancer), heart attack, stroke, transient ischemic attack, angina pectoris, coronary-artery bypass grafting, or percutaneous coronary intervention; 3. have none of the following safety exclusions: history of renal failure or dialysis, hypercalcemia, hypo- or hyperparathyroidism, severe liver disease (cirrhosis), or sarcoidosis or other granulomatous diseases such as active chronic tuberculosis or granulomatosis with polyangiitis (Wegener's); 4. have no allergy to fish or soy; 5. have no other serious illness that would preclude participation; 6. be consuming no more than 800 IU of vitamin D from all supplemental sources combined (individual vitamin D supplements, calcium+vitamin D supplements, medications with vitamin D \[e.g., Fosamax Plus D\], and multivitamins), or, if taking, willing to decrease or forego such use during the trial; 7. be consuming no more than 1200 mg/d of calcium from all supplemental sources combined, or, if taking, willing to decrease or forego such use during the trial; 8. not be taking fish oil supplements, or, if taking, willing to forego their use during the trial
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Brigham and Women's Hospital
Boston, Massachusetts, 02215, United States
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