Definition of Women's Health Initiative

Women's Health Initiative: A long-term national health study that focuses on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in postmenopausal women. This 15-year project sponsored by the National Institutes of Health (NIH) involves over 161,000 women aged 50-79. The WHI Clinical Trial and Observational Study has three study components.The components are:

  • Hormone Replacement Therapy (HRT): This component examines the effect of HRT on the prevention of heart disease and osteoporosis, and any associated risk for breast cancer. Women participating in this component take hormone pills or a placebo (inactive pill).
  • Dietary Modification: The Dietary Modification component evaluates the effect of a low-fat, high fruit, vegetable and grain diet on the prevention of breast and colorectal cancer and heart disease. Study participants follow either their usual eating pattern or a low-fat eating program.
  • Calcium/Vitamin D: This component starts up to 2 years after a woman joins one or both of the other studies. It evaluates the effect of calcium and vitamin D supplementation on the prevention of osteoporosis-related fractures and colorectal cancer. Women in this component take calcium and vitamin D pills or a placebo.

The WHI Community Prevention Study (CPS), a 5-year cooperative venture with CDC, is a study of strategies to enhance adoption of healthful behaviors through a multi-disciplinary approach. The purpose of the CPS is to develop community-based public health interventions models which will achieve healthful behaviors in women aged 40 and over.


Last Editorial Review: 6/14/2012

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