Selenium

Selenium is a chemical element with the symbol Se and atomic number 34, classified as a nonmetal and a member of group 16 (the oxygen family) of the periodic table. It has an atomic mass around 78.96 g/mol and occurs naturally in various allotropes, including gray metallic crystalline forms and red amorphous powders. Selenium is solid at room temperature, with a melting point around 220–221 °C and a boiling point near 685 °C. It has a density of about 4.81 g/cm³ in its solid form

Appearance:

• Red selenium: amorphous, brick-red powder, reactive and insulating.

• Black selenium: vitreous (glassy) solid, brittle, lustrous, also an insulator.

• Gray selenium: metallic-looking, most stable allotrope, gray crystalline solid, semiconductor with photoconductive properties. 

Solubility:

• Slightly soluble in carbon disulfide (CS₂) for red and black forms.

• Gray form is insoluble in CS₂.

Melting Point: 220 °C

Selenium is essential for synthesizing antioxidant selenoproteins that protect cells from oxidative damage, aid DNA synthesis, support reproduction, and regulate thyroid hormone metabolism.

The key benefits of selenium for human health include:

• Powerful antioxidant: Selenium helps fight oxidative stress by neutralizing excess free radicals, protecting cells from damage linked to aging, heart disease, cancer, and other chronic conditions.

• Reduces risk of certain cancers: Higher selenium blood levels are associated with lower risks of breast, lung, colon, and prostate cancers, likely due to its roles in DNA protection, immune boosting, and oxidative stress reduction.

• Supports heart health: Selenium may lower heart disease risk by reducing inflammation and oxidative stress, which contribute to artery plaque buildup and cardiovascular problems.

• Boosts immune function: Adequate selenium improves immune cell function, enhancing the body’s defense against infections like HIV, influenza, tuberculosis, and hepatitis C.

• Thyroid health: Selenium is essential for thyroid hormone synthesis and metabolism, supporting overall metabolic regulation and preventing thyroid disorders.

• Cognitive and neurological support: Selenium’s antioxidant properties protect brain cells, potentially reducing risks of neurodegenerative diseases like Alzheimer’s and Parkinson’s.

• Supports reproductive health: Selenium is important for sperm health and protects reproductive cells from oxidative damage, though supplement benefits are still being studied.

• May reduce asthma symptoms: Selenium’s anti-inflammatory effects might help lessen symptoms in asthma patients, but more research is needed.