Parkinson's Disease Linked To High Iron Intake

Those who had the highest level of iron in their diets – in the top 25 percent – were 1.7 times more likely to be Parkinson's patients than those in the lowest 25 percent of iron intake. Those whose level of both iron and manganese was higher than average were 1.9 times more likely to be Parkinson's patients than those with lower than average intake of the minerals.

Iron and manganese contribute to oxidative stress, a situation where cells release toxic substances called free radicals as part of normal energy consumption and metabolism.

"Oxidative stress may cause degeneration of brain cells that produce dopamine – the same cells that are affected by Parkinson's disease," said study author Harvey Checkoway, PhD, of the University of Washington in Seattle.

People who had higher than average dietary iron intake and who also took, on average, one or more multivitamins or iron supplements per day were 2.1 times more likely to be Parkinson's patients than those who had lower than average dietary iron intake and who took fewer than one multivitamin or iron supplement per day.

Those who had higher than average dietary manganese intake and also took an average of one or more multivitamins per day were 1.9 times more likely to be Parkinson's patients than those who had lower than average dietary manganese intake and who took less than one multivitamin per day.

Additional studies are necessary to confirm these results, Checkoway said.

Foods rich in both iron and manganese include spinach, legumes, nuts and whole grains. Iron is also abundant in red meat and poultry.

Checkoway said that the benefits of eating foods rich in iron and manganese and in taking multivitamins outweigh the risks of developing Parkinson's disease.

"Our findings may improve understanding of how Parkinson's disease develops," he said. "But, there are most likely numerous environmental, lifestyle and genetic factors that determine who will develop the disease. It's too early to make any recommendations about potential dietary changes."

The research was supported by grants from the National Institute of Environmental Health Sciences.

The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, autism and multiple sclerosis.