The Women’s Health Initiative (WHI) is one of the most comprehensive studies on women’s postmenopausal health. Its 20-year findings provide insight into the effects of hormone therapy, calcium and vitamin D supplements, and a low-fat diet on postmenopausal health [1].
This blog explores these results and their implications for millions of postmenopausal women worldwide.
Hormone therapy: Risks and benefits
Hormone therapy has been a hot topic for decades, especially when it comes to managing menopausal symptoms.
The WHI study included two hormone treatments: conjugated equine estrogens (CEE) combined with medroxyprogesterone acetate (MPA) for women with a uterus and CEE by itself for those who had a hysterectomy.
The results of the trial revealed some key findings:
- Women using CEE plus MPA had a 24% higher risk of breast cancer over 5.6 years compared with those taking a placebo.
- The therapy also increased the risk of stroke by 37% and pulmonary embolism by 98%.
- On the positive side, this combination lowered the risk of hip fractures by 33%.
For women taking CEE alone, the WHI found a different pattern of risks and benefits:
- Unlike the combination therapy, CEE alone was linked to a 21% lower risk of breast cancer over a median follow-up of 7.2 years.
- However, it increased the risk of stroke by 35%, reinforcing the need for caution.
Ultimately, the WHI concluded that hormone therapy is not suitable for preventing chronic diseases like cardiovascular disease or dementia.
However, it is effective in managing moderate to severe menopausal symptoms, especially when started before age 60.
Calcium and Vitamin D: A mixed bag for bone health
The WHI trial also examined the impact of calcium and vitamin D supplements on bone health and fracture prevention. Postmenopausal women are often at risk for osteoporosis, making this research highly relevant.
Surprisingly, the findings showed that supplementing with calcium and vitamin D did not significantly reduce the risk of hip fractures in the general population of postmenopausal women.
The annualized hip fracture rate was 0.14% in the supplement group compared with 0.16% in the placebo group.
However, for women aged 60 and above, supplementation showed more promise, reducing hip fractures by 21%.
These results highlight that vitamin D and calcium supplements can be beneficial for women with higher fracture risk, but they may not be universally effective.
Low-fat diet: Not as protective as once thought
One of the most anticipated aspects of the WHI was its investigation into a low-fat dietary pattern. The trial focused on reducing total fat intake to 20% of daily calories while increasing the consumption of fruits, vegetables, and grains.
Unfortunately, the diet did not significantly reduce breast cancer or colorectal cancer rates over a median follow-up of 8.5 years.
However, long-term follow-up showed that women who followed the low-fat diet had a 21% lower risk of dying from breast cancer.
Interestingly, while the diet intervention didn’t yield the expected results for heart disease prevention, it did lead to slight improvements in cholesterol levels and a small reduction in body weight (1.9 kg at year 1).
These outcomes suggest that a low-fat diet may still have benefits, particularly for metabolic health.
Key takeaways
The WHI’s 20-year data provide vital insights into postmenopausal health, and the findings have already shaped clinical practices. Here are a few key takeaways:
- Hormone therapy shouldn’t be used to prevent chronic diseases but can be an effective treatment for menopausal symptoms, especially when started early.
- Calcium and vitamin D supplementation is not a one-size-fits-all solution for fracture prevention. Women at higher risk of fractures or with low baseline intake may benefit the most.
- A low-fat dietary pattern did not prevent breast cancer but showed promise for reducing breast cancer mortality in the long run.
The WHI’s findings emphasize the importance of personalized care, especially for postmenopausal women.
Hormone therapy, dietary interventions, and supplementation should be guided by each woman’s risks, lifestyle, and health goals.
This extensive study continues to inform healthcare providers and individuals about the best strategies for supporting postmenopausal health and well-being.
This study is published on the JAMA Network.
[1] JAMA Network. The Women’s Health Initiative Randomized Trials and Clinical Practice
