Selenium 200 mcg By GNC Overview & Drug Interactions

Calcium is a vital nutrient found in various foods such as dairy products, certain vegetables, and many fortified items. Over 99% of the body's calcium is stored in the bones and teeth, predominantly as hydroxyapatite. The remaining calcium circulates in the blood, extracellular fluid, muscles, and other tissues, where it is essential for processes like nerve signaling, muscle contraction, vascular activities, glandular secretion, and maintaining cell membrane and capillary permeability. It also plays critical roles in enzyme reactions, respiration, kidney function, and blood clotting, and is involved in neurotransmitter and hormone release, amino acid uptake, vitamin B12 absorption, and gastrin secretion. Calcium balance changes with age: it is positive during periods of growth, stable in adulthood, and tends to become negative in older age. Calcium loss occurs through feces, urine, sweat, and shedding skin cells. In women, reduced estrogen levels decrease calcium absorption and retention, increase bone turnover, and lead to lower bone mass. Calcium supplements come in various forms, including citrate and carbonate, which differ mainly in their calcium content and absorption rates. Calcium citrate is easily absorbed and can be taken without food, making it suitable for older adults or those with low stomach acid. In contrast, calcium carbonate, which contains a higher percentage of calcium, is best absorbed when taken with meals.

Selenium is an essential trace element that plays a crucial role in various physiological functions in the human body. It is often included in dietary supplements due to its antioxidant properties and its contribution to maintaining a healthy immune system. Selenium is important for thyroid function and may also have a role in protecting against certain chronic diseases. However, it's essential to note that excessive selenium intake can be harmful, so it's crucial to adhere to recommended daily allowances and consult with a healthcare professional before taking selenium supplements.