|MadSci Network: Chemistry|
Hi, In some ways, the Ca found in foods like milk are similar to that found in plants, but there are differences. In milk and dairy prodcuts much of the Ca is found as Ca ions (associated with the whey protein alpha-lactalbumin) or as Ca phosphate (associated with some of the casein proteins). Being associated with milk proteins, which are very digestable, makes this Ca more bioavailable than Ca found in plants. In plants, the Ca is also in the forms of salts (oxalate, citrate, etc.), which are less soluble making the Ca less bioavailable. Plants can also contain antinutrients (chealtors which can bind divalent cations such as Ca) which can bind minerals and make them less available. Cooking does aide in reducing the effect of some of these antinutrients. Some Ca ions are involved in muscle contraction and as cofacotors for enzymatic reactions but this is only a small amount of the total concentration in animals or plants. In vertebrates, much of the Ca is found associated with bone. I hope this helps to answer you questions. Sincerely, Al Bushway Professor of Fod Science
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