Excess levels of a mineral responsible for healthy blood and brain function may raise the risk of Parkinson's disease and dementia, a study suggests. Iron is an essential mineral that helps make hemoglobin, a protein in red blood cells that carries oxygen from the lungs to the rest of the body's vital tissues. The body cannot produce iron on its own, and it instead comes from animal proteins such as lean red meat, clams and oysters, along with plant-based foods like spinach, lentils, tofu and white beans. Iron deficiency, which affects one in seven Americans, or 36 million people, has also been linked to developmental issues and cognitive decline, as the mineral also supports energy and neurotransmitter production.But researchers at the Salk Institute in California have found that excess iron can slowly accumulate inside neurons. While this has little effect early in life, for older adults, it may cause nerve cells to die. They believe this is because excess iron lowers cells' defenses, which makes them more vulnerable to stressors. Cell death in areas of the brain responsible for memories and cognitive function, such as the hippocampus and cerebral cortex, can lead to dementia, which affects about 7 million Americans. And striking 1 million Americans, Parkinson's disease is caused by the loss of neurons responsible for producing dopamine, which coordinates movement, so the death of these cells could contribute to the disease. A new study found an accumulation of iron may lead to cell changes associated with dementia and Parkinson's disease