In May 2019 researchers from the USA published the results of their study to assess whether calcium and vitamin D supplementation changes the effect of menopausal hormone replacement therapy (HRT) on cardiovascular events (coronary heart disease, stroke, pulmonary embolism, heart attack, angioplasty and deep venous thrombosis). A total of 27,347 menopausal women were included in the study, some of whom had undergone a hysterectomy. The women were given HRT or a placebo and, after 1 year, 16,089 women were given either 1,000 mg of calcium and 400 IU of vitamin D3 daily or placebo in addition to their HRT. Those who had undergone a hysterectomy were followed up for an average of 6 years and those not having had a hysterectomy being followed for an average of 5 years. Results showed that those women on HRT who had undergone a hysterectomy appeared to have an increased risk of stroke. However the calcium and vitamin D supplementation appeared to reduce this risk although it did not appear to have any effect on cardiovascular diseases. When the results were analysed in those women who had not undergone a hysterectomy, calcium and vitamin D supplementation did not appear to influence the effects of HRT on any cardiovascular disease, including that of stroke.
Jiang X et al. Women’s Health Initiative clinical trials: potential interactive effect of calcium and vitamin D supplementation with hormonal therapy on cardiovascular disease. Menopause. 2019 Aug;26(8):841-849