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Dietary magnesium does not predict ischaemic heart disease in the Caerphilly cohort
P C Elwood1, A M Fehily, H Ising
1MRC Epidemiology Unit, Llandough Hospital, Penarth, South Glamorgan.
Insights
Dietary magnesium intake showed a trend towards being associated with a lower risk of ischaemic heart disease (IHD). However, after accounting for confounding factors like age and smoking, this link lost statistical significance in the Caerphilly cohort study.
Area of Science:
- Cardiovascular epidemiology
- Nutritional science
- Public health
Background:
- Ischaemic heart disease (IHD) remains a leading cause of mortality worldwide.
- Dietary factors, including magnesium, are investigated for their potential role in cardiovascular health.
- Understanding the relationship between nutrient intake and IHD risk is crucial for preventative strategies.
Purpose of the Study:
- To investigate the association between dietary magnesium intake and the incidence of ischaemic heart disease events.
- To determine if magnesium intake is an independent predictor of IHD risk.
Main Methods:
- Dietary magnesium intake was assessed using food frequency and 7-day weighted intake records in 2172 men aged 45-59.
- The incidence of IHD events, including acute deaths and non-fatal myocardial infarctions, was prospectively recorded over a 10-year follow-up period.
- Statistical analyses, including relative odds calculations and adjustments for confounding factors, were performed.
Main Results:
- Men who experienced IHD events had lower mean daily magnesium intakes compared to those without events (266 vs 281 mg/day).
- Men with acute IHD deaths exhibited even lower magnesium intakes (mean 253 mg/day).
- While initial analyses showed a higher risk of IHD with lower magnesium intake (RO 1.86), this association became non-significant after adjusting for confounders (RO 1.52).
Conclusions:
- The Caerphilly cohort data suggest a trend between lower dietary magnesium intake and increased IHD risk.
- However, the study did not find conclusive evidence that dietary magnesium intake is an independent predictor of ischaemic heart disease in this population.
- Further research may be needed to clarify the role of magnesium in cardiovascular disease prevention.
Objectives:
To examine the association between dietary magnesium intake and the risk of an ischaemic heart disease (IHD) event.
Design:
Estimates were made of dietary magnesium intake from food frequency records, supplemented by seven-day weighted intake records. The subsequent incidence of ischaemic heart disease events was recorded. The relative odds of an IHD event was related to base-line magnesium intake.
Setting:
Data on dietary magnesium intakes are available for 2172 men aged 45-59 y in the Caerphilly cohort. These have now been followed for ten years since base-line dietary data were collected, and during this time a total of 269 IHD events occurred. Of these, 96 were acute deaths (ICD 410) and 136 were non-fatal myocardial infarctions.
Results:
The overall mean dietary intake of magnesium was estimated to be 279 (s.d. 83) mg/day. The daily intake of those men who later experienced any IHD event was 266 (s.d. 84) mg/day and this differs from that in men who experienced no IHD event during this time (281 mg, P < 0.05). Men who suffered an acute IHD death had even lower intakes (mean 253 (s.d. 79); P < 0.005). Age, smoking habit, energy intake and alcohol consumption are all significantly associated with both Mg intake and IHD risk and are therefore possible confounding factors. Standardisation for these factors reduces the difference for all IHD events to 2.9 (s.e.m. 3.6) mg Mg/day, P > 0.05, and to 0.9 (s.e.m. 5.8) mg for acute IHD death. Similarly, when the men are ranked into fifths by their daily Mg intake, 70 of the 434 men with the lowest intakes went on to experience an IHD event, compared with only 41 of the 434 men with the highest Mg intakes. The relative odds (RO) for the fifth of men with the lowest intakes, compared with the fifth with the highest intakes, is 1.86 (P < 0.005), but standardisation for the confounding factors leads again to a loss of significance (RO 1.52, P > 0.05).
Conclusion:
Although trends in the data are suggestive, data from the Caerphilly cohort give no certain evidence that dietary magnesium intake is independently predictive of ischaemic heart disease in the population studied.