High serum levels of the mineral were also linked to a 40 per cent lower risk of all-cause mortality, and a reduction of similar magnitude for cardiovascular deaths. High serum levels of both copper and zinc however were associated with increased risk of death from all-causes.
The research is important because dietary surveys show that a large portion of adults do not meet the RDA for magnesium, found naturally in green, leafy vegetables, meats, starches, grains and nuts, and milk.
"It's the first epidemiological study which shows synergistic effects on mortality of low serum zinc and high serum copper, as well as the effects of low serum zinc and low serum magnesium and these interactions may be physiopathologically plausible as these minerals are involved in the immune system, the inflammatory response and the oxidative damage," lead author Dr Nathalie Leone from the Pasteur Institute in Lille, INSERM Unit 744, told NutraIngredients.com.
The research, published in the journal Epidemiology (Vol. 17, pp. 308-314), reports from the Paris Prospective Study 2, a cohort of over 4,000 men aged between 30 and 60 at the start of the study.
After 18 years of follow-up 339 subjects had died, with 176 due to cancer and a further 56 from cardiovascular disease (CVD). Serum analysis of magnesium, copper and zinc levels showed that highest serum level of magnesium (0.85 millimoles per litre or more) compared to the lowest level (0.76 millimoles per litre or less) was associated with a reduction in the risk of all-cause mortality, death from cancer, and CVD of 40, 50 and 40 per cent, respectively.
The highest serum levels of copper (16.4 micromoles per Litre or more), associated with older age, high cholesterol and smoking, was linked to a 50 per cent increase in all-cause mortality, 40 per cent increase for cancer mortality, and a 30 per cent increase in CVD deaths, compared to the lowest serum levels (13.5 micromoles per litre or less).
This is not the first time that high copper levels have been linked to negative health effects. In September, high copper intake was linked to decreased lung strength, while recent research out of the US suggested that the body could not excrete all of the copper when taken in amounts higher than that found in the diet. Excess copper could be associated with reduced immune function and lower antioxidant status, according to a team from the Agricultural Research Service.
It is these changes in oxidative stress and the resulting inflammation that the mineral levels may be affecting health, suggest the researchers.
Dr Leone stressed that the intake of the nutrients was not studied: "So for the moment, we cannot conclude about a potential causality link between these serum minerals and cancer or cardiovascular mortality. Whether these minerals are partly responsible for, or are biomarkers of, cancer and cardiovascular disease remains to be established.
Further studies, in particular interventional studies, are needed to confirm the interactions between serum zinc and serum copper or serum magnesium and the prediction of all-cause, cancer and cardiovascular mortality in clinical practice," she said.