Because aluminum enters our bodies through food, water, antiperspirants, antacids(drug) and some cooking utensils. This relates to a theory of aging known as "cross-linking," when the binding together of proteins, carbohydrates, abnormal cells and other substances with the assistance of an agent such as aluminum. These substances make tight knots that just getting bigger and more tangled. They collect in our bones, contributing to osteoporosis, and in our brains, causing Alzheimer's disease. You can help reduce this process by replacing all your aluminum cookware and by not taking antacids(drug). Equally important is a natural, whole-food diet, which will slow the rate of cross-linking and break down the "tangles."