Researchers examined the magnesium intake of 4,365 patients over 12 years (including follow-up) and found an inverse relationship between mineral levels and CVD mortality.
A high magnesium intake of 322 mg daily was associated with a lower risk of CVD and total mortality, and especially among participants taking diuretics.
Based on current results and previous evidence, the authors suggest that magnesium intake may be more strongly associated with mortality risk in CVD patients than in the general population.
“Our findings highlight the importance of adequate magnesium intake in patients with cardiovascular disease, in addition to treatment with cardiovascular medications.” write the researchers in Frontiers in Cardiovascular Medicine.
“The highest risk of CVD mortality was observed at below-average magnesium intakes. Estimates of protective risk for CVD mortality are shown for magnesium intakes above adequate intakes.
The findings add to an ever-growing body of science supporting the mineral’s potential health benefits. The National Institutes of Health (NIH) lists magnesium as necessary for more than 300 biochemical reactions in the body, from helping maintain normal muscle and nerve function to maintaining a steady heart rate, maintaining a healthy immune system, and maintaining healthy bones. The mineral is also needed for blood sugar management and healthy blood pressure.
European experts recommend a daily magnesium intake of 350 mg for men and 300 mg for women, as adequate levels can help control blood sugar levels, blood pressure and myocardial metabolism.
Hypomagnesemia can also lead to insulin resistance, altered lipid metabolism, and impaired endothelial and renal function.
Requirements may be different for patients with CVD who have physiological changes in their cardiovascular system, are more prone to co-morbidities, and who are taking drugs that may interfere with absorption. In addition, the effects of magnesium intake on long-term mortality risks are unclear.
Therefore, the present study investigated the relationship between dietary magnesium and CVD, all-cause, and CHD mortality in patients with a previous myocardial infarction and who were taking medication.
Male and female participants with a mean age of 69 years were recruited from the cohort participating in the Alpha Omega trial, where MI patients were followed to evaluate the effects of low-dose omega-3 fatty acids or placebo for 40 months .
Dietary intake was assessed with the FFQ, which examined food and drink frequency, amount, type of food and methods of preparation. Supplement use was determined with a self-reported lifestyle and health questionnaire.
The results of the questionnaire found that magnesium supplements were used by 235 (5.4%) of the patients and the mean total magnesium intake was about 300 mg/day.
The researchers adopted Cox proportional hazard models to assess the association between energy-adjusted magnesium intake and mortality risk factors, and restricted cubic splines (RSC) to determine continuous and threshold associations.
Effect of diuretics
The results show a direct link between magnesium status and a lower risk of cardiovascular disease in both men and women. There was no significant association between magnesium intake and death from coronary heart disease (CHD).
The authors wrote that a difference of 100 mg/day in magnesium intake was associated with a 30-40% lower risk of CVD and all-cause mortality in several subgroups.
They note that protective associations are more evident in the presence of diuretics and speculate that they may affect magnesium status by inhibiting renal sodium and indirectly affecting magnesium absorption.
“Based on sensitivity analyzes by diuretic type, we conclude that both thiazide diuretics and potassium-sparing diuretics may be involved in the association between magnesium intake and CVD mortality,” they wrote.
Effect of dietary fiber
The presence of dietary fiber, rather than magnesium, may also explain the inverse association with CVD mortality, the authors say, because both are derived from similar food sources and were strongly associated in the study.
Population-based studies have identified an association between dietary fiber and moral CVD risks, but most did not adjust for magnesium, so protective elements may be associated with both compounds, they say.
In addition, the researchers conducted subgroup and sensitivity analyzes that revealed inverse associations for magnesium in patients with low and high fiber intakes and in users of magnesium-depleted diuretics.
“Based on the totality of findings, we believe that magnesium intake independent of fiber may have contributed to the lower risk of CVD mortality in the Alpha Omega cohort,” they wrote.
Finally, they suggested that the study’s limitations should be considered in the context of the findings, given the observational nature of the study and the shortcomings of self-report — and despite adjustments for confounders such as dietary and lifestyle factors.
source: Frontiers in Cardiovascular Medicine
Published online 12 August 2022: doi: 10.3389/fcvm.2022.936772
“Dietary magnesium and risk of cardiovascular and total mortality after myocardial infarction: a prospective analysis in the Alpha Omega cohort”
Author: I. Evers, et al.