Alkaline earth metal second only to calcium
Strontium (SR) is ubiquitous in nature and human tissues, and is the second most abundant alkaline earth metal in the earth's crust after calcium. The intake of strontium in the human body mainly depends on the amount of strontium in the diet, and the daily intake of dietary strontium by a normal adult is about 2-4mg, of which 07-2.0mg from drinking water, 12-2.3mg comes from foods (vegetables, cereals, nuts and dairy products).
The percentage of strontium in the human body is much lower than that of calcium and magnesium and belongs to trace elements. Calcium and magnesium are recognized as essential elements, and the necessity of strontium for the human body has not been determined by the WHO.
The strontium content in the dry weight of plants ranged from 3 10-6 to 400 10-6, which was related to plant varieties and enrichment ability, and was generally considered to be higher in leafy vegetables. The concentration of strontium in the human body is about 46 10-6 Based on the weight of a healthy adult weighing about 70kg, the total amount of strontium in the body is about 320mg. The distribution of strontium in the human body varies widely, with less than 1% of strontium in 99% present in bones and teeth, blood and body fluids, and strontium <50 10-9 in normal healthy** serum.
Osteotropic properties
Most of the strontium in the human body is ingested orally, and a small amount of strontium can enter the human body through tissues such as ** and lungs, absorbed by the digestive tract and metabolized by blood circulation, and finally excreted in the form of feces, urine, sweat, milk and hair loss. The main site of strontium absorption in the human body is the jejunum, and its absorption process requires the synergy of calcitriol and calcium ions, which is completed through the intestinal epithelial calcium channel transporter.
Strontium is found in the human body to:sr2＋The form is present, and it is approximately contained in the normal **body320mgMore than 99% of them are found in bones and teeth, and the rest are mainly found in tissues such as blood, hair, and muscles. The distribution and metabolism of strontium in the human body are similar to calcium, and both have "osteotropic properties". Bone strontium and blood strontium are constantly exchanged, so that the strontium in the human body is always in a state of dynamic equilibrium. In general,The strontium content in bones increased with the increase of the collective intake of strontium dose, the increase of blood strontium content and the prolongation of strontium ingestion time, showing a positive correlation.
Current research finds:The main factors affecting strontium absorption are: First, the intake of strontium increases, as well as the age of the individual and the increase in the amount of calcium in the food, the absorption of strontium will occur relatively reduced. The second is the increase in vitamin levels in the human body, and the increase in carbohydrates and lactose in foodIt may also promote the absorption of strontium.
Unique strontium-containing mineral water
Strontium is not highly abundant in the earth's crust, but it is widely distributed. Strontium element can not exist alone in nature, it is very easy to be oxidized to form strontium compounds, strontium minerals are mainly lazurite (mainly strontium sulfate) and strontium rhosite (mainly strontium carbonate, strontium oxide) two kinds, these rocks after long-term weathering, erosion, leaching and other natural actions, in which strontium enters the groundwater in the form of ions.
GB8537-2018 "National Food Safety Standard for Drinking Natural Mineral Water" stipulates that strontium is onlyStrontium in water reaches 0At 20mg L, it can be named strontium-containing natural mineral water。There are more than 1,000 strontium-containing mineral water sources that have been surveyed and identified in China, accounting for about 30% of the total number of natural mineral water in China, and it is the second largest type of metasilicic acid mineral water in terms of quantity.
Strontium and osteoporosis
Osteoporosis is a metabolic disease caused by the disruption of the homeostatic balance of bone formation and reabsorption in the body, and is more common in older and postmenopausal women. Under normal circumstances, the ratio of calcium salts to matrix in bone tissue is normal, while in loose bone, calcium salts to matrix are reduced, but the ratio of both is normal. In osteoporosis, the vast majority of the decrease in bone tissue is due to increased bone resorption due to increased osteoclasts due to osteopenia.
At present, the drugs of osteoporosis mainly improve osteoporosis by increasing bone formation, inhibiting bone resorption, regulating mesenchymal stem cell differentiation and enhancing bone strength. In countries that have not yet obtained a license for strontium raniate**Stable strontium salts (strontium citrate, strontium chloride, etc.) can be used as an alternative dietary supplement for patients with osteoporosisPatients in these countries have freely and voluntarily purchased and taken these strontium salts for the relief of osteoporosis.
A woman in Minnesota, USA, with a history of osteoporosis of the vertebrae, took 680mg of strontium chloride daily for two and a half years and experienced a significant increase in bone density in her vertebrae and right hip joint. Studies have shown that a female patient with a history of osteoporosis who voluntarily took strontium citrate for two and a half years had her bone mineral density in her knuckles and ankles increased to 7 and 15 times the initial value.
Strontium and infertility
According to the World Health Organization**, infertility may become the third most common disease in the 21st century, after oncology and cardiovascular disease. Currently, about 48.5 million couples worldwide are affected by infertility. In China, the incidence of infertility is as high as 25%, and it is increasing year by year. Therefore, it is particularly urgent to find and improve the best way to improve infertility.
Some scholars have studied the changes of pig sperm motility, acrosome morphology and fertilization ability after strontium chloride treatment, and found that strontium ions have a positive effect on the changes of pig sperm fertilization ability. Another scholar studied 8 couples with low fertilization rate or complete fertilization failure, and found that after activating oocytes with strontium chloride, the fertilization rate and the proportion of high-quality cleavage embryos increased. The results of clinical trials showed:Activation of artificial oocytes with a culture medium containing strontium ions after intracytoplasmic sperm injection can improve fertilization rates, clinical pregnancy rates, and live birth rates.
Through these studies, we can see that strontium not only has a positive effect on improving the quality of human **, but also can improve male reproductive health by inhibiting oxidative stress and regulating the expression level of testosterone and testosterone synthesis-related genes. In addition, strontium can also affect the formation and function of female egg cells, which can promote the improvement of the success rate of artificial insemination and the prevention of infertility.
Strontium and caries prevent decay
Some scholars studied 1313 children aged 12-14 years in Wisconsin, USA, and found that the prevalence of dental caries was quadratic with the concentration of strontium in drinking water, and the prevalence of dental caries in urban children with a concentration of strontium in drinking water was the lowest.
Some scholars put hydroxyapatite in 1After soaking in 0 mol l strontium nitrate for 24 h, it was found that the modulus and flexural strength of hydroxyapatite increased compared with the untreated hydroxyapatite. Some scholars have also researched the incorporation of strontium into the crystal lattice of hydroxyapatite, and found that strontium can inhibit the dissolution of hydroxyapatite and improve the biological activity and stability of hydroxyapatite.
The strontium content in tooth enamel is closely related to the strontium content in the external environment such as drinking water and food. When the concentration of strontium in drinking water was less than 10 mg L, the strontium content in tooth enamel was positively correlated with the strontium content in drinking water. When the mass concentration of strontium in drinking water is higher than 10 mg L, the strontium content in tooth enamel remains approximately 300 g g mb.