A two-compartment model for zinc in humans

Area of Science:

• Human Nutrition
• Trace Element Metabolism
• Radiotracer Kinetics

Background:

• Zinc is an essential trace element crucial for numerous physiological processes.
• Accurate assessment of zinc absorption and body stores is vital for understanding nutritional status.
• Previous studies often employed complex models or stable isotopes for zinc kinetics.

Purpose of the Study:

• To quantify oral zinc absorption from a mixed meal in healthy adults.
• To determine total body zinc (TBZn) and zinc turnover using a simple compartmental model.
• To evaluate the correlation between TBZn and lean body mass.

Main Methods:

• Oral administration of the radiotracer 65Zn in a test meal (beef, potatoes, peas).
• Measurement of 65Zn absorption percentage in 19 healthy adults.
• Longitudinal whole-body and whole-blood retention tracking in 9 subjects.
• Analysis using a two-compartment model to estimate TBZn and zinc turnover.
• Correlation analysis with total body potassium (40K) for lean body mass estimation.

Main Results:

• Oral zinc absorption was determined to be 20% +/- 5%.
• TBZn ranged from 15.5 to 35.9 mmol, with zinc turnover from 0.043 to 0.073 mmol/d.
• A strong correlation was observed between TBZn and total body potassium.
• The rapidly exchanging zinc pool was estimated between 3.2 and 5.6 mmol.

Conclusions:

• A simple radiotracer method and compartmental model effectively estimate short- and long-term zinc behavior in the body.
• The findings align with results from more complex radiotracer and stable isotope studies.
• This approach provides valuable insights into zinc metabolism and body burden in humans.