Human Jejunal Calcium, Magnesium, Zinc Absorption

Calcium is the most abundant cation and fifth common inorganic element of the human body. It plays a vital role in a variety of of essential physiologicaland biochemical process. Increasing attention has been given to the research on calcium and calcium absorption of small intestine.Triple lumen intestinal perfusion technique is a method which has the advantage that net absorption or secretion of nutrients can be measured from a specific segment of the small bowel under the physiological conditions.It has been noted that calcium is related to the severity of osteoporosis, but the controversy is present in the relationship between calcium absorption of small intestine and the occurrence of osteoporosis.Glucose polymer derived from partial hydrolysis of corn starch offers the advantages of low osmolality, minimal sweetness and good efficiency of absorption It has been proved that glucose polymer can increase the calcium absorption of small bowel in rats and normal people, but the benifit of it to the patients with senile osteoporosis is unknown.The present study investigates the net absorption of calcium, magnesium and zinc from human jejunum in different age groups(including normal young people, normal middle aged people and the patients with senile osteoporosis) by triple lumen perfusion test.The results show that: The net calcium absorption of normal middle aged people is only 1/3 of the young people. The patients with senile osteoporosis show calcium net secretion. The magnesium absorption of normal people is higher than that of the patients. The zinc absorption of normal middle aged people is 3-fold of the patients, but lower than that of the young.It seems that calcium, magnesium and zinc absorption of human jejunum decreases as the age increases, especially in the cases with senile osteoporosis. The calcium absorption of human jejunum is positive related to the bone density, implying that there is a closed relationship between small intestinal calcium absorption and the onset of senile osteoporosis. The kenetic analysis of jejunal calcium absorption indicates that the impaired calcium active(saturable) absorption is the main cause of the age related calcium malabsorption and maybe attributed to 1,25(OH)VitD.The results also show that glucose polymer can increase jejunal calcium , magnesium and zinc absorption in both normal people and patients with senile osteoporosis. The mechanism is solvent drag. In patients with senile osteoporosis, because active calcium absorption is reduced, the enhancing effect of glucose polymer on calcium absorption has a practical value, it should be a benefitial formula in prevention and treatment of senile osteoporosis.