Structure, Function, and Nutrition of Calcium-Containing Proteins or Peptides from Foodstuffs
Calcium is an essential nutrient required for critical biological functions such as nerve conduction, muscle contraction, mitosis, blood coagulation, and structural support of the skeleton. Therefore, dietary calcium intake is of general interest for huma
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Structure, Function, and Nutrition of Calcium-Containing Proteins or Peptides from Foodstuffs Chenyan Lv
Abstract Calcium is an essential nutrient required for critical biological functions such as nerve conduction, muscle contraction, mitosis, blood coagulation, and structural support of the skeleton. Therefore, dietary calcium intake is of general interest for human beings. Low dietary intake of calcium is also associated with higher risks of osteoporosis, colon cancer, and hypertension. This chapter focuses on structure, function, and nutrition of key calcium-containing proteins or peptides from both dairy and plant products. Keywords Calcium • Peptides • Binding • Bioavailability
5.1 The Distribution and Bioavailability of Calcium Calcium is an important component of a healthy diet and is necessary for human life. In our body, approximately 99% of calcium is stored in the bones and teeth [1]. The remaining calcium (1%) in the body plays significant roles in the neurotransmitter release and muscle contraction. Generally, the total concentration of calcium in blood is 2.25–2.75 mM. Among the total calcium, about 46.0% are bound with proteins including albumin and globulin, 6.5% of them are bound with inorganic acids, and others are mainly ionized calcium. A lifelong deficit can affect bone and tooth formation severely. Similarly, over-retention can cause hypercalcemia, impaired kidney function, and decreased absorption of other minerals. Generally, the body obtains the needed calcium in two ways. One is by eating calcium- containing food. The well-known sources of calcium include dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark leafy greens or dried beans, which have varying amounts of absorbable calcium. C. Lv (*) School of Public Health, Beijing Key Laboratory of Environmental Toxicology, Capital Medical University, Beijing 100069, China e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2017 G. Zhao (ed.), Mineral Containing Proteins, DOI 10.1007/978-981-10-3596-8_5
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Another way is by pulling it from bones. It happens when calcium levels in blood drop too low. Although this doesn’t always happen, the payback can’t be accomplished simply by eating more calcium. Therefore, sufficient calcium intake during daily life is crucial for preventing osteoporosis. As for the calcium sources, the majority of dietary calcium (70%) comes from dairy products and casein micelles constitute the natural vector of calcium in milk. Nevertheless, some individuals are allergic to dairy products and even more people are lactose intolerant, leaving them unable to consume these dairy products. Besides, vegans avoid dairy products for ethical and health reasons. In addition, numerous vegetables, notably spinach, chard, and rhubarb, have high calcium content, but they may also contain varying amounts of oxalic acid that binds calcium and thus reduces its absorption. Previous researches on the absorption of calcium have indicated that the bioa
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