Intestinal absorption of aluminium.

Area of Science:

• Toxicology
• Gastroenterology
• Environmental Health

Background:

• Intestinal absorption of aluminum contributes significantly to systemic exposure.
• Aluminum uptake occurs from various sources including pharmaceuticals, food, and water.
• Absorption is not limited to individuals with kidney disorders, affecting healthy subjects as well.

Purpose of the Study:

• To elucidate the mechanisms and factors influencing intestinal aluminum absorption.
• To review the current understanding of aluminum absorption pathways and determinants.
• To highlight the variability in absorption across different physiological conditions.

Main Methods:

• Review of in vitro studies (e.g., everted gut sac models).
• Analysis of animal studies (e.g., intestinal perfusion).
• Consideration of human case reports and limited controlled studies.

Main Results:

• Intestinal absorption depends on intraluminal factors: aluminum speciation, quantity, pH, and presence of competing (iron, calcium) or complexing (citrate) substances.
• Host factors significantly modulate absorption, including iron status, calcium/vitamin D/parathyroid hormone status, age, and kidney function.
• Multiple absorption sites and routes (transcellular, paracellular) exist, linked to different aluminum species.

Conclusions:

• A comprehensive understanding of intestinal aluminum absorption requires considering numerous interacting factors.
• No single mechanistic model currently explains aluminum absorption applicable to all clinical situations.
• Further research is needed to develop a unified model for predicting clinical aluminum exposure from intestinal absorption.