NEW YORK (Reuters Health) - People who eat lots of iron from plant sources may be at increased risk of Parkinson's disease, especially if their vitamin C intake is on the low side, a study suggests.

There is some evidence for a link between iron intake, or environmental exposure to the metal, and Parkinson's disease. However, studies of dietary iron intake and Parkinson's risk have had mixed results, the study team notes in the American Journal of Epidemiology.

To investigate further, Dr. Giancarlo Logroscino of the University of Bari in Italy and colleagues analyzed data on 47,406 men and 79,947 women participating in the Health Professionals Follow-Up Study or the Nurses' Health Study. Between 1984 and 2000, 422 developed Parkinson's disease.

The researchers found that people who consumed the most non-heme iron -- meaning iron from plant sources rather than meat -- were at 30 percent greater risk of Parkinson's than those who consumed the least.

The risk was 92 percent greater for people with both a high non-heme iron intake and a low vitamin C intake. Men who took iron supplements also showed a slightly greater Parkinson's risk than those who didn't. Fortified cereals and grains were the main source of non-heme iron in the participants' diets.

Iron could plausibly contribute to Parkinson's disease by boosting oxidative damage in the brain, the researchers note. And non-heme iron, which is less readily absorbed in the body, is the main type of iron that accumulates in the brain. Some studies have found increased iron deposits in brain regions affected by Parkinson's disease.

The recommended iron intake for men over 18 and women over 50 is 8 milligrams a day, the researchers note, while people in the study who had a greater Parkinson's risk were taking in more than twice this recommended amount.

The current findings, the study team concludes, "should be considered cautiously, and they need to be replicated in other settings, possibly with biomarkers, to measure systemic iron stores and metabolism."

SOURCE: American Journal of Epidemiology

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