Aluminum exposure and metabolism

Area of Science:

• Toxicology
• Human Physiology
• Environmental Health

Background:

• Aluminum (Al) is a nonessential, toxic metal with frequent human exposure via pharmaceuticals, food, water, and medical solutions.
• Exposure routes include oral, parenteral (intravenous, TPN, dialysis), and inhalation, posing risks to human health.

Purpose of the Study:

• To elucidate the mechanisms of aluminum absorption and excretion in the human body.
• To understand the factors influencing aluminum bioavailability and tissue accumulation.

Main Methods:

• Review of existing literature on aluminum absorption, transport, and excretion pathways.
• Analysis of factors affecting gastrointestinal absorption, including speciation and co-ingested substances.
• Examination of renal and potential biliary excretion mechanisms.

Main Results:

• The gastrointestinal tract is a primary barrier, limiting oral aluminum absorption to less than 1%.
• Aluminum absorption mechanisms involve passive and active transcellular and paracellular transport, potentially sharing pathways with calcium.
• Renal excretion is limited due to protein complexation in plasma; biliary secretion's role and mechanisms remain poorly understood and appear saturable.

Conclusions:

• The gut's role in limiting aluminum absorption is significant, but absorption mechanisms require further elucidation.
• Understanding aluminum's complex interactions with other substances and its limited excretion pathways is crucial for managing toxicity.
• Further research is needed to clarify biliary excretion and overall aluminum homeostasis.