Relationship Between Dietary Magnesium Intake and Incident Heart Failure Among Older Women: The WHI.

Background Women represent a large proportion of the growing heart failure (HF) epidemic, yet data are lacking regarding optimal dietary and lifestyle prevention strategies for them. Specifically, the association between magnesium intake and HF in a multiracial cohort of women is uncertain. Methods and Results We included 97 725 postmenopausal women from the WHI (Women's Health Initiative) observational studies and placebo arms of the hormone trial. Magnesium intake was measured at baseline by a 122-item validated food-frequency questionnaire and stratified into quartiles based on diet only, total intake (diet with supplements), and residual intake (calibration by total energy). Incident hospitalized HF (2153 events, median follow-up 8.1 years) was adjudicated by medical record abstraction. In Cox proportional hazards models, we evaluated the association between magnesium intake and HF adjusting for potential confounders. Analyses were repeated on a subcohort (n=18 745; median-follow-up, 13.2 years) for whom HF cases were subclassified into preserved ejection fraction (526 events), reduced ejection fraction (291 events) or unknown (168 events). Most women were white (85%) with a mean age of 63. Compared with the highest quartile of magnesium intake, women in the lowest quartile had an increased risk of incident HF, with adjusted hazard ratios of 1.32 (95% CI, 1.02-1.71) for diet only (P trend=0.03), 1.26 (95% CI, 1.03-1.56) for total intake, and 1.31 (95% CI, 1.02-1.67) for residual intake. Results did not significantly vary by race. Subcohort analyses showed low residual magnesium intake was associated with HF with reduced ejection fraction (hazard ratio, 1.81, lowest versus highest quartile; 95% CI, 1.08-3.05) but not HF with preserved ejection fraction. Conclusions Low magnesium intake in a multiracial cohort of postmenopausal women was associated with a higher risk of incident HF, especially HF with reduced ejection fraction.

Association of Dietary Magnesium Intake with Fatal Coronary Heart Disease and Sudden Cardiac Death.

Background: Postmenopausal women represent the highest population-based burden of cardiovascular disease, including sudden cardiac death (SCD). Our understanding of the etiology and risk factors contributing to fatal coronary heart disease (CHD) and SCD, particularly among women, is limited. This study examines the association between dietary magnesium intake and fatal CHD and SCD. Materials and Methods: We examined 153,569 postmenopausal women who participated in the Women's Health Initiative recruited between 1993 and 1998. Magnesium intake at baseline was assessed using a validated food frequency questionnaire, adjusting for energy via the residual method. Fatal CHD and SCD were identified over an average follow-up of 10.5 years. Results: For every standard deviation increase in magnesium intake, there was statistically significant risk reduction, after adjustment for confounders, of 7% for fatal CHD (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.89-0.97), and 18% risk reduction for SCD (HR 0.82, 95% CI 0.58-1.15) the latter of which did not reach statistical significance. In age-adjusted quartile analysis, women with the lowest magnesium intake (189 mg/day) had the greatest risk for fatal CHD (HR 1.54, 95% CI 1.40-1.69) and SCD (HR 1.70, 95% CI 0.94-3.07). This association was attenuated in the fully adjusted model, with HRs of 1.19 (95% CI 1.06-1.34) for CHD and 1.24 (95% CI 0.58-2.65) for SCD for the lowest quartile of magnesium intake. Conclusions: This study provides evidence of a potential inverse association between dietary magnesium and fatal CHD and a trend of magnesium with SCD in postmenopausal women. Future studies should confirm this association and consider clinical trials to test whether magnesium supplementation could reduce fatal CHD in high-risk individuals.

Women's Health Initiative clinical trials: potential interactive effect of calcium and vitamin D supplementation with hormonal therapy on cardiovascular disease.

OBJECTIVE: Data in humans and nonhuman primates have suggested a possible synergistic effect of vitamin D and calcium (CaD) and estrogen on the cardiovascular disease (CVD) risk factors. Using randomized trial data we explored whether the effect of menopausal hormone therapy (HT) on CVD events is modified by CaD supplementation. METHODS: A prospective, randomized, double-blind, placebo-controlled trial was implemented among postmenopausal women in the Women's Health Initiative. A total of 27,347 women were randomized to the HT trials (0.625 mg/d of conjugated equine estrogens [CEE] alone for women without a uterus vs placebo; or 0.625 mg of CEE in addition to 2.5 mg of medroxyprogesterone acetate daily [CEE + MPA] for women with a uterus vs placebo). After 1 year, 16,089 women in the HT trial were randomized to the CaD trial and received either 1,000 mg of elemental calcium carbonate and 400 IU of vitamin D3 daily or placebo. The mean (SD) duration of follow-up after CaD randomization was 6.2 (1.3) years for the CEE trial and 4.6 (1.1) years for the CEE + MPA trial. CVD and venous thromboembolism events evaluated in this subgroup analysis included coronary heart disease, stroke, pulmonary embolism, all-cause mortality, plus select secondary endpoints (total myocardial infarction, coronary revascularization, deep venous thrombosis, cardiovascular death, and all CVD events). Time-to-event methods were used and models were fit with a Cox proportional hazards regression model. RESULTS: In the CEE trial, CaD significantly modified the effect of CEE on stroke (P interaction = 0.04). In the CaD-placebo group, CEE's effect on stroke was harmful (hazard ratio [95% confidence interval] = 2.19[1.34-3.58]); however, it was neutral in the CaD-supplement group (hazard ratio [95% confidence interval] = 1.07[0.66-1.73]). We did not observe significant CEE-CaD interactions for coronary heart disease, total CVD events, or any of the remaining endpoints. In the CEE + MPA trial, there was no evidence that the effect of CEE + MPA on any of CVD endpoints was modified by CaD supplementation. CONCLUSIONS: CaD did not consistently modify the effect of CEE therapy or CEE + MPA therapy on CVD events. However, the increased risk of stroke due to CEE therapy appears to be mitigated by CaD supplementation. In contrast, CaD supplementation did not influence the risk of stroke due to CEE + MPA.

Effects of Calcium, Vitamin D, and Hormone Therapy on Cardiovascular Disease Risk Factors in the Women's Health Initiative: A Randomized Controlled Trial.

OBJECTIVE: To analyze the treatment effect of calcium+vitamin D supplementation, hormone therapy, both, and neither on cardiovascular disease risk factors. METHODS: We conducted a prospective, randomized, double-blind, placebo-controlled trial among Women's Health Initiative (WHI) participants. The predefined primary outcome was low-density lipoprotein cholesterol (LDL-C). RESULTS: Between September 1993 and October 1998, a total of 68,132 women aged 50-79 years were recruited and randomized to the WHI-Dietary Modification (n=48,835) and WHI-Hormone Therapy trials (n=27,347). Subsequently, 36,282 women from WHI-Hormone Therapy (16,089) and WHI-Dietary Modification (n=25,210) trials were randomized in the WHI-Calcium+Vitamin D trial to 1,000 mg elemental calcium carbonate plus 400 international units vitamin D3 daily or placebo. Our study group included 1,521 women who participated in both the hormone therapy and calcium+vitamin D trials and were in the 6% subsample of trial participants with blood sample collections at baseline and years 1, 3, and 6. The average treatment effect with 95% confidence interval, for LDL-C, compared with placebo, was -1.6, (95% confidence interval [CI] -5.5 to 2.2) mg/dL for calcium+vitamin D alone, -9.0 (95% CI -13.0 to -5.1) mg/dL for hormone therapy alone, and -13.8 (95% CI -17.8 to -9.8) mg/dL for the combination. There was no evidence of a synergistic effect of calcium+vitamin D+hormone therapy on LDL-C (P value for interaction=.26) except in those with low total intakes of vitamin D, for whom there was a significant synergistic effect on LDL (P value for interaction=.03). CONCLUSION: Reductions in LDL-C were greater among women randomized to both calcium+vitamin D and hormone therapy than for those randomized to either intervention alone or to placebo. The treatment effect observed in the calcium+vitamin D+hormone therapy combination group may be additive rather than synergistic. For clinicians and patients deciding to begin calcium+vitamin D supplementation, current use of hormone therapy should not influence that decision. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT00000611.

Risk of heart failure among postmenopausal women: a secondary analysis of the randomized trial of vitamin D plus calcium of the women's health initiative.

BACKGROUND: Vitamin D supplementation may be an inexpensive intervention to reduce heart failure (HF) incidence. However, there are insufficient data to support this hypothesis. This study evaluates whether vitamin D plus calcium (CaD) supplementation is associated with lower rates of HF in postmenopausal women and whether the effects differ between those at high versus low risk for HF. METHODS AND RESULTS: Analyses were restricted to 35 983 (of original 36 282) women aged 50 to 79 years old in the Women's Health Initiative randomized trial of CaD supplementation who were randomized 1:1 in a double-blinded fashion to receive 1000 mg/d of calcium plus 400 IU/d of vitamin D3 or placebo. Overall, 744 adjudicated incident HF cases (intervention, 363; control, 381) occurred during a median follow-up of 7.1 (interquartile range, 1.6) years. CaD supplementation, compared with placebo, was not associated with reduced HF risk in the overall population, hazard ratio, 0.95; P=0.46. However, CaD supplementation had differential effects (P interaction=0.005) in subgroups stratified by baseline risk status of HF defined by the presence (high risk=17 449) or absence (low risk=18 534) of pre-existing HF precursors including coronary heart diseases, diabetes mellitus, or hypertension: 37% (hazard ratio, 0.63 [95% confidence interval, 0.46-0.87]) lower risk of HF in the low-risk versus hazard ratio, 1.06; P=0.51, in the high-risk subgroups. CONCLUSIONS: CaD supplementation did not significantly reduce HF incidence in the overall cohort, however, it was beneficial among postmenopausal women without major HF precursors while of little value in high-risk subgroups. Additional studies are warranted to confirm these findings and investigate the underlying mechanism. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000611.

Calcium/vitamin D supplementation, serum 25-hydroxyvitamin D concentrations, and cholesterol profiles in the Women's Health Initiative calcium/vitamin D randomized trial.

OBJECTIVE: The objective of this study was to evaluate whether increased serum 25-hydroxyvitamin D3 (25OHD3) concentrations, in response to calcium/vitamin D (CaD) supplementation, are associated with improved lipids in postmenopausal women. METHODS: The parent trial was a double-blind, randomized, placebo-controlled, parallel-group trial designed to test the effects of CaD supplementation (1,000 mg of elemental calcium + 400 IU of vitamin D3 daily) versus placebo in postmenopausal women. Women from the general community, including multiple sites in the United States, were enrolled between 1993 and 1998. This cohort included 300 white, 200 African-American, and 100 Hispanic participants who were randomly selected from the Women's Health Initiative CaD trial. Serum 25OHD3 and lipid (fasting plasma triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], and calculated low-density lipoprotein cholesterol [LDL-C]) levels were assessed before and after CaD randomization. RESULTS: There was a 38% increase in mean serum 25OHD3 concentrations after 2 years (95% CI, 1.29-1.47, P < 0.001) for women randomized to CaD (24.3 ng/mL postrandomization mean) compared with placebo (18.2 ng/mL). Women randomized to CaD had a 4.46-mg/dL mean decrease in LDL-C (P = 0.03). Higher concentrations of 25OHD3 were associated with higher HDL-C levels (P = 0.003), along with lower LDL-C and TG levels (P = 0.02 and P < 0.001, respectively). CONCLUSIONS: Supplemental CaD significantly increases 25OHD3 concentrations and decreases LDL-C. Women with higher 25OHD3 concentrations have more favorable lipid profiles, including increased HDL-C, lower LDL-C, and lower TG. These results support the hypothesis that higher concentrations of 25OHD3, in response to CaD supplementation, are associated with improved LDL-C.

Calcium, magnesium and potassium intake and mortality in women with heart failure: the Women's Health Initiative.

Although diet is thought to affect the natural history of heart failure (HF), nutrient intake in HF patients has not been well studied. Based on prior research linking high intake of Ca, Mg and K to improved cardiovascular health, we hypothesised that these nutrients would be inversely associated with mortality in people with HF. Of the 161 808 participants in the Women's Health Initiative (WHI), we studied 3340 who experienced a HF hospitalisation. These participants were followed for post-hospitalisation all-cause mortality. Intake was assessed using questionnaires on food and supplement intake. Hazard ratios (HR) and 95 % CI were calculated using Cox proportional hazards models adjusted for demographics, physical function, co-morbidities and dietary covariates. Over a median of 4·6 years of follow-up, 1433 (42·9 %) of the women died. HR across quartiles of dietary Ca intake were 1·00 (referent), 0·86 (95 % CI 0·73, 1·00), 0·88 (95 % CI 0·75, 1·04) and 0·92 (95 % CI 0·76, 1·11) (P for trend = 0·63). Corresponding HR were 1·00 (referent), 0·86 (95 % CI 0·71, 1·04), 0·88 (95 % CI 0·69, 1·11) and 0·84 (95 % CI 0·63, 1·12) (P for trend = 0·29), across quartiles of dietary Mg intake, and 1·00 (referent), 1·20 (95 % CI 1·01, 1·43), 1·06 (95 % CI 0·86, 1·32) and 1·16 (95 % CI 0·90, 1·51) (P for trend = 0·35), across quartiles of dietary K intake. Results were similar when total (dietary plus supplemental) nutrient intakes were examined. In summary, among WHI participants with incident HF hospitalisation, intakes of Ca, Mg and K were not significantly associated with subsequent mortality.

A prospective study of serum 25-hydroxyvitamin D levels, blood pressure, and incident hypertension in postmenopausal women.

In randomized trials, the effect of vitamin D supplementation on blood pressure has been equivocal, while most prospective cohort studies have shown that the risk of incident hypertension is lower in people with higher levels of 25-hydroxyvitamin D (25(OH)D). The authors examined the association between levels of 25(OH)D and changes in blood pressure and incident hypertension in 4,863 postmenopausal women recruited into the Women's Health Initiative between 1993 and 1998. Over 7 years, there were no significant differences in the adjusted mean change in systolic or diastolic blood pressure by quartile of 25(OH)D. The covariate-adjusted risk of incident hypertension was slightly lower in the upper 3 quartiles of 25(OH)D compared with the lowest quartile, but this was statistically significant only in the third quartile (hazard ratio = 0.67, 95% confidence interval: 0.46, 0.96). There was no significant linear or nonlinear trend in the risk of incident hypertension by untransformed or log-transformed continuous values of 25(OH)D. In postmenopausal women in this study, serum levels of 25(OH)D were not related to changes in blood pressure, and evidence for an association with lower risk of incident hypertension was weak.

Effect of 5 y of calcium plus vitamin D supplementation on change in circulating lipids: results from the Women's Health Initiative.

BACKGROUND: Dietary calcium and vitamin D intakes may be inversely associated with cardiovascular disease (CVD) risk, possibly because of their potential beneficial effects on circulating lipids. Clinical trials that have evaluated the effect of calcium supplementation on lipids are limited by a short follow-up, and data on vitamin D are scarce. OBJECTIVE: The objective was to evaluate the effect of a longer-term effect (over 5 y) of calcium and vitamin D (CaD) supplementation on changes in the concentrations of several lipids: LDL, HDL, non-HDL, total cholesterol, triglycerides, and lipoprotein(a) [Lp(a)]. DESIGN: The study was conducted in 1259 postmenopausal women in the Calcium plus Vitamin D Trial (1 g elemental Ca as carbonate plus 400 IU vitamin D(3)/d compared with placebo) of the Women's Health Initiative. Analyses were conducted by intention-to-treat. Repeated measurements on lipids during follow-up were analyzed by linear mixed-effects models. RESULTS: Overall, the change in lipids was relatively small [< or =5% except for Lp(a), which was 20-25%], and there was no significant difference in the mean change of any lipid variable between the active and placebo groups. CONCLUSIONS: Our results indicate that CaD supplementation is not associated with lipid changes over 5 y. Existing and future CaD trials should consider evaluating this association for different doses of supplements. This study was registered at clinicaltrials.gov as NCT00000611.