Calcium requirements for the human body during growth

Fetal period: People need calcium supplementation throughout their lives. Starting from the third month of pregnancy, the fetus's need for calcium increases suddenly. Low calcium in the mother will directly affect the fetus' height, weight, head, spine and limbs. If the mother continues to be calcium deficient, it will cause leg cramps, miscarriage, dystocia, pelvic deformity, and even serious obstetric complications during pregnancy, such as pregnancy-induced hypertension, epilepsy, proteinuria, edema, etc., which seriously endanger the lives of the fetus and the mother. To avoid the above problems, the calcium intake during pregnancy is 800-1200 mg per day. When dietary calcium intake is insufficient, it should be supplemented in time.
Neonatal period: Neonatal period (within 28 days after birth): During this stage, the fetus has a self-generated low calcium period to stimulate the start of the calcium self-stabilizing system. During this stage, a large amount of calcium nutrition needs to be taken from breast milk. Due to the lack of vitamin D in breast milk, if it is not supplemented in time after 2 weeks of birth, dangerous symptoms such as low calcium, convulsions, and asthma may occur.
Infancy: Infancy (birth to 3 years old): This stage is the most active metabolic period in a person's life. The brain and body develop rapidly, and the deciduous teeth grow out. The amount of calcium in the body at this time will directly affect the early growth and development. If calcium is deficient, delayed teething, anorexia, hyperhidrosis, baldness on the back of the head, pigeon chest, O-shaped legs, X-shaped legs, upper respiratory tract infections, indigestion, enteritis, etc. may occur, which will bring inconvenience to life and growth.
Preschool to adolescence: Preschool, school age to adolescence (before 3 to 18 years old): This stage grows faster, the weight of the brain increases, the internal structure of the brain develops completely, permanent teeth grow out, and the nervous system matures. After puberty, the epiphysis gradually heals, the growth of height begins to slow down and gradually stops. If calcium supplementation misses this stage, it will directly affect the health status in adulthood.
Adulthood: Adulthood (18-45 years old): During this stage, the body's bone calcium storage reaches its peak, but during this period, the pressure of work, study, and life increases, which will consume a lot of calcium in the body. If calcium is not supplemented during this period, various senile diseases will be caused. Middle-aged and elderly (after 45 years old): With the increase of age, a large amount of calcium nutrition in the body is consumed, and calcium needs to be transferred from the bones to the blood, resulting in a decrease in bone density and osteoporosis. The loss of bone calcium in the elderly can reach 30% to 50%. Long-term transfer of bone calcium into the blood may lead to an increase in the amount of calcium in blood vessels, tissues, and cells. As a result, calcium accumulates in the blood vessel walls, myocardium, and kidneys, causing numbness of the whole body, neurasthenia, emotional indifference, constipation, drowsiness, sexual dysfunction, arteriosclerosis, coronary heart disease, diabetes, calculi, tumors and other senile diseases. At this time, the C cells of the thyroid gland will secrete calcitonin to promote bone calcium reduction. During the reduction process, free calcium is formed in the ectopic deposition of the edge of the large joints - bone hyperplasia. In other words, bone hyperplasia is caused by calcium deficiency. These pathological and physiological changes have caused troubles in the lives of many middle-aged and elderly people.
Plants: Purple alfalfa has the highest calcium content among plants. The optimal ratio of calcium: magnesium: phosphorus in the human body is 2:1:1, but phosphorus can be taken in food, and people's usual dietary intake of phosphorus has exceeded the ratio. The ratio of calcium to magnesium for children is 4:1.
Plants absorb calcium ions from salts such as calcium chloride. Calcium in plants is in ionic form, namely Ca2+. Calcium is mainly found in old organs and tissues of leaves, and it is an element that is not easy to move. Calcium can serve as a bridge between the phosphate group of phospholipids and the carboxyl group of proteins in biological membranes, thereby maintaining the stability of membrane structure.
Calcium in the cytosol combines with soluble protein, calmodulin (also known as calmodulin, camlmodulin, CaM), to form an active Ca·CaM complex, which plays the role of "second messenger" in metabolic regulation.
Calcium is an element that constitutes the cell wall, and the intercellular layer of the cell wall is composed of calcium pectate. When calcium is deficient, cell wall formation is blocked, affecting cell division, or new cell walls cannot be formed, resulting in multinucleated cells. Therefore, growth is inhibited when calcium is deficient, and in severe cases, young organs (root tips, stem ends) rot and die. Tomato stem rot, lettuce top blight, celery stem split disease, spinach black heart disease, Chinese cabbage dry heart disease, etc. are all caused by calcium deficiency.
Calcium ions and potassium ions work together to regulate stomatal closure: when the stomata are closed, the closing signal stimulates calcium ions to enter the cytosol, depolarize the membrane, open anion channels, and release chloride ions and malic acid. According to this principle, the loss of anions will further depolarize, open potassium ion channels, and potassium ions will passively extend to the adjacent accessory cells and epidermal cells, and the stomata will close.