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

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 CaCO 3 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. as well as a variety of chemical reactions, have all been successfully prepared via mechanical milling. The products produced by milling operations include reactive chemicals, large-surface-area catalysts, quasi-crystalline, amorphous, and non-crystalline materials, as well as some supersaturated solid solutions [23]. EDAMM produces faster responses as well as innovative synthesis and processing techniques using low current and high voltage. Calcium oxide can be fully replenished only 15 minutes after using EDAMM. Similar results were obtained using conventional calcium carbonate calcination. Calcium carbonate must be converted to calcium oxide at a high temperature of 900°C [22].