The document discusses the causes and effects of calcium deficiency. It states that lack of calcium can be caused by acids found in soda and acid rain. Diseases related to calcium deficiency include osteoporosis, infertility, and dermatitis herpetiforme. Osteoporosis causes bones to become weak and fragile, increasing the risk of fractures. The document recommends consuming calcium-rich foods like milk, fruits, vegetables, and fish to prevent calcium-deficiency diseases.