A diet rich in magnesium - found in foods like leafy greens, fish, nuts and whole grains - may help lower the risk of chronic health problems like heart disease and diabetes, a research review suggests.
Some previous studies linked insufficient magnesium levels to a greater risk of developing a wide range of health problems including chronic obstructive pulmonary disease (COPD), diabetes, Alzheimer's disease, and cardiovascular disease, said lead study author Dr. Xuexian Fang, a nutrition researcher at Zhengzhou University in China.
For the current study, Fang and colleagues analyzed data on dietary magnesium and chronic disease from 40 studies published from 1999 to 2016 on more than one million people across nine countries.
Compared with people who had the lowest levels of magnesium in their diets, people who got the most magnesium were 10 percent less likely to develop heart disease, 12 percent less likely to have a stroke and 26 percent less likely to develop diabetes.
"Magnesium plays an important role in maintaining human health," Fang said by email.
Combined, the studies in the analysis included 7,678 cases of cardiovascular disease, 6,845 cases of coronary heart disease, 701 cases of heart failure, 4,755 cases of stroke, 26,299 cases of type 2 diabetes and 10,983 deaths.
When researchers looked at the effect of increasing dietary magnesium by 100 milligrams a day, they didn't find a statically meaningful impact on the total risk of cardiovascular disease or coronary heart disease.
But they did find that increasing dietary magnesium by this amount was tied to a 22 percent reduction in the risk of heart failure, and a 7 percent decrease in the risk of stroke, researchers report in the journal BMC Medicine.
Increasing magnesium intake was also associated with a 19 percent reduction in the risk of diabetes and a 10 percent drop in the odds of death from all causes during the study period.
The analysis is based on observational studies and can't prove magnesium directly prevents disease, the authors note.
Studies in the analysis also relied on participants to accurately recall and report what foods they consumed and may not have accurately reflected the true amount of dietary magnesium, the researchers point out.
It's also impossible to rule out the potential for lifestyle factors that impact people's eating habits to also influence how much magnesium they get in their diets and how prone they are to develop chronic diseases.
Still, the study findings suggest that increased consumption of magnesium-rich foods may have health benefits, the authors conclude.
While the exact way magnesium improves health isn't clear, it's possible it may help curb inflammation, which in turn may lower the odds of developing a variety of chronic diseases, Fang said.
There are many ways people may increase their magnesium intake, noted Dr. Andrea Romani, a researcher at Case Western Reserve University in Cleveland, Ohio, who wasn't involved in the study.
Magnesium is present in high levels in all green, leafy vegetables, whole grains, nuts, and salt-water fish, Romani said by email. It's less clear how much magnesium is in meat and poultry because this depends on what the animals eat.
"Magnesium retention in these foods depends on how the food is processed," Romani said. "The longer it is boiled or cooked, the less magnesium is retained."