Strontium is a naturally occurring element widely found in the environment, present in soil, water, and various foods. It is an alkaline earth metal, sharing chemical similarities with calcium, a more abundant element in the human body. Strontium exists as a trace element within the human body, primarily from dietary intake.
Entry Point: The Digestive System
The primary route for strontium to enter the human body is through dietary intake. Once ingested, strontium is absorbed into the bloodstream predominantly within the digestive system, specifically the small intestine. This absorption process is not entirely efficient, with studies indicating that the fraction of ingested strontium transferred to plasma can vary significantly, often ranging from approximately 10% to 45% in healthy adults.
The efficiency of absorption can differ based on individual variations and the functional state of the gastrointestinal tract. Once absorbed from the small intestine, strontium enters the systemic circulation. This initial absorption from the gut is the first step for strontium to become available for physiological processes within the body.
Strontium’s Journey to Bone
After being absorbed into the bloodstream, strontium is distributed throughout the body, behaving similarly to calcium. Due to its chemical and physical resemblance to calcium, strontium is primarily deposited in bones and teeth. Approximately 99% of the strontium in the human body is concentrated within the skeletal system, including the femur, lumbar spine, and iliac bone.
Strontium becomes incorporated into the bone matrix alongside calcium, essentially replacing some calcium ions within the mineral structure of bone. Bones serve as a reservoir for strontium, and like calcium, it can be released back into the bloodstream over time as bone undergoes its natural remodeling process.
Factors Influencing Strontium Absorption
Several factors can influence the amount of strontium absorbed from the digestive system. Dietary calcium intake plays a significant role; higher levels of calcium in the diet can reduce strontium absorption due to competition for the same absorption pathways in the small intestine. Conversely, low dietary calcium levels may enhance strontium absorption.
Vitamin D status also indirectly affects strontium absorption, as vitamin D influences calcium absorption and metabolism. Age is another factor, with absorption rates differing between infants and adults; infants may absorb a higher percentage of ingested strontium compared to older individuals. The specific chemical form of ingested strontium can also affect its bioavailability and absorption efficiency.