The exact causes of Alzheimer’s disease are still unknown, but experts have identified a host of contributing factors: diabetes, smoking, saturated fats. Now a theory points the finger in a different direction: a variety of metals that can build up in the body over time. Look inside the brains of people with Alzheimer’s who have died and you’ll find protein clogging the brain’s signaling system, along with tiny clusters called beta-amyloid plaques. “When researchers tease those plaques apart, they find metals, including iron, copper, and aluminum,” says Neal Barnard, MD, an adjunct associate professor of medicine at the George Washington University School of Medicine. “These metals produce free radicals, which are like little sparks that damage brain cells.” And dementia isn’t the only risk; metals have been linked to everyday mental fuzziness: A study of roughly 1,450 adults in The Journal of Nutrition, Health & Aging found that women who performed highest on cognition tests had the lowest levels of copper and iron in their blood. But you needn’t let metals meddle with your noggin: A few simple swaps can help shield your brain and protect your memory.