Analysis of calcium-lipid complexes in faeces

Area of Science:

• Gastroenterology
• Nutritional Science
• Biochemistry

Background:

• Calcium is hypothesized to prevent colorectal cancer by forming insoluble complexes with bile acids and long-chain fatty acids in the colon.
• A method to analyze these calcium-lipid complexes in feces is crucial for investigating this mechanism.

Purpose of the Study:

• To develop and validate a method for quantifying calcium-lipid complexes in human feces.
• To investigate the effect of calcium intervention on fecal calcium-lipid complexes in patients with adenoma.

Main Methods:

• Organic synthesis of authentic calcium soaps of long-chain fatty acids and bile acids.
• Quantification of calcium palmitate using 72% ethanol extraction and precipitation.
• Application of the developed method to fecal samples from a placebo-controlled calcium-intervention study.

Main Results:

• Human feces contain significant amounts of calcium long-chain fatty acid soaps, primarily calcium palmitate and stearate.
• Calcium intervention significantly increased fecal long-chain fatty acid soaps (P = 0.005) but did not affect free long-chain fatty acid excretion (P = 0.4).
• Formation of calcium long-chain fatty acid soaps depends equally on fecal long-chain fatty acid and calcium concentrations.

Conclusions:

• The developed method can quantify calcium long-chain fatty acid soaps in human feces.
• Calcium intervention effectively increases fecal long-chain fatty acid soap formation.
• Calcium soaps of bile acids were not detected, suggesting they do not form or are not quantifiable by this method.