Egg Shell: An Essential Waste Product to Improve Dietary Calcium Uptake Download PDF

Since the human skeletal system is composed primarily of calcium (98%), calcium is one of the most fundamentally important and necessary elements for the human body. The current review paper aimed to address egg shell (ES) deposition, its nutritional composition, theories of calcium absorption, and the significance of calcium in daily life. ES formation occurs in two stages. Calcium carbonate, weighing 5.5 grams, makes up approximately 95% of the dried ES. Approximately 0.3% of phosphorus, 0.3% of magnesium, and traces of sodium, potassium, zinc, manganese, iron, and copper can all be found in one ES. Calcium absorption depends on vitamin D, therefore dietary intake and vitamin D status both affect how much calcium is bioavailable. Numerous locations along the nephron may be sites of calcium reabsorption. Some factors have been demonstrated to positively increase calcium absorption, including intestinal acidity (especially for CaCO₃ absorption), oestrogen, vitamin D, and soluble fiber/prebiotics, probiotics, and synbiotics. Studies have been done on pertinent processes that can be utilized to extract calcium from ESs, including pulsed electric fields, high-energy milling, and electric discharge-assisted mechanical milling. The study focused on the nutritional benefits of eggshells as well as several eggshell extraction techniques to determine their economic viability in producing a sufficient calcium supplement.