The Importance of Calcium in the Context of Postmenopausal Changes and Osteoporosis

Calcium represents a foundational mineral that is indispensable for maintaining skeletal integrity, playing a pivotal role in bone mineralization and growth processes. An overwhelming 99% of the body’s total calcium reserves are deposited within the skeletal framework, where it serves as the primary structural component not only of bones but also of teeth, nails, and cartilaginous tissues. The remaining 1% circulates within systemic fluids and soft tissues, participating in the regulation of critical physiological functions. Beyond its structural contributions, calcium is instrumental in modulating skeletal and smooth muscle contractility, supporting cardiac function and neural conductance, and playing a vital role in blood coagulation mechanisms as well as hormone synthesis and secretion. Additionally, it contributes to the regulation of arterial blood pressure. Given its multifunctional nature, consistent dietary intake of calcium is imperative. Daily requirements fluctuate based on sex, age, and physiological status, with markedly increased demands during adolescence (due to rapid skeletal growth), pregnancy, and advanced age. Standard recommendations for adults range between 1000–1200 mg per day. While dairy products—such as milk, cheese, and yogurt—are widely recognized as the most abundant sources of bioavailable calcium, adequate intake can also be achieved through dairy-free diets by incorporating plant-based alternatives. Calcium-rich foods include legumes (soybeans, asparagus beans), leafy greens (kale), oilseeds (sunflower seeds, poppy seeds, sesame, chia), and nuts (almonds). Fortified products, such as tofu or plant-based beverages, as well as high-mineral spring waters, can serve as supplementary sources. However, the bioavailability of calcium is influenced by several factors—dietary fiber, oxalic acid, and phytates (commonly found in plant foods) may significantly impede its intestinal absorption. Maintaining an appropriate calcium-to-phosphorus ratio in the diet (at least 1:1, ideally favoring calcium) is equally critical, as excessive phosphorus intake—prevalent in processed foods (deli meats, processed cheeses, instant soups, carbonated beverages)—can disrupt calcium metabolism. The highest absorption rates are observed with calcium derived from fermented dairy products, including natural yogurts, kefir, and hard cheeses.