COcoa Supplement and

Multivitamin Outcomes Study

Thank you for your interest in the COcoa Supplement and Multivitamin Outcomes Study (COSMOS),

an exciting new randomized clinical trial, being conducted by researchers at Brigham and Women’s Hospital in Boston and the Fred Hutchinson Cancer Research Center in Seattle.  COSMOS will study the role of cocoa extract (including flavanols and other natural compounds in the cocoa bean) and multivitamins in improving health. The trial will be conducted entirely by mail, with no required clinic visits.


Studies have found that cocoa extract may reduce the risk of heart disease and age-related cognitive decline.  Multivitamin use was found to modestly reduce cancer risk in a previous trial of 14,641 male physicians.  As a large-scale clinical trial, COSMOS will allow us to further explore these findings in both men and women definitively.


If you are a man aged 60 or older or a woman aged 65 or older, have not previously had a heart attack or stroke, and have not been diagnosed with cancer (other than skin cancer) within the past 2 years, you may be eligible to participate in COSMOS.  Participation involves taking 3 study pills each day for 4 years – 2 cocoa extract or placebo capsules, and 1 multivitamin or placebo tablet – from convenient monthly calendar packs. The placebos look exactly like the cocoa extract or multivitamin, but contain none of the active ingredients.


You will be assigned to a treatment group at random (as by the flip of a coin) and will not know what your pills contain until the end of the study. We will send you a new supply of study pills every 6 months to one year, along with a questionnaire asking about your recent health, health habits, and whether you have been taking your study pills. All information that you provide will be held strictly confidential and used only for medical research purposes. If you are eligible for the study, you may be eligible for sub-studies and for possible compensation.


To participate, you must agree not to take (apart from the study pills) any cocoa extract supplements or multivitamins including eye vitamins. In addition, you will be asked to limit your total intake of vitamin D from supplements (other than foods) to no more than 1000 IU per day, including stand-alone vitamin D supplements and other medications that contain vitamin D. You will also be asked to limit your total intake of calcium from supplements (other than foods) to no more than 1200 mg per day.


We very much hope that you will collaborate with us on this important study.







If you have any questions or concerns, please contact us at 1-800-633-6913 or

We look forward to working together to answer important research questions.



JoAnn E. Manson, MD

Harvard Medical School


Howard D. Sesso, ScD

Harvard Medical School


Garnet Anderson, PhD

Fred Hutchinson Cancer Research Center



Brigham and Women’s Hospital  | Division of Preventive Medicine | 900 Commonwealth Avenue  |  Boston, MA  02215  |  800-633-6913