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Relationship between endogenous 3-methylhistidine excretion and body composition
The American Journal of Physiology
|March 1, 1981
Summary
Urinary 3-methylhistidine (3MH) excretion is a reliable indicator of muscle protein degradation in humans. This study found a strong correlation between 3MH levels and muscle mass, supporting its use as a biomarker under controlled dietary conditions.
Area of Science:
- Human physiology
- Biochemistry
- Nutritional science
Background:
- Accurate assessment of muscle protein degradation is crucial for understanding human metabolism and health.
- Urinary 3-methylhistidine (3MH) is a potential biomarker for muscle protein breakdown, but its relationship with muscle mass needs further validation.
- Dietary intake, particularly meat consumption, can influence 3MH excretion levels.
Purpose of the Study:
- To investigate the relationship between endogenous urinary 3-methylhistidine (3MH) excretion and total-body muscle mass (MM) in healthy men.
- To determine if 3MH can serve as a reliable in vivo marker for muscle protein degradation.
- To assess the impact of controlled dietary conditions (meat diet vs. meal-free diet) on 3MH excretion.
Main Methods:
- Fourteen healthy men (20-30 years) participated in a crossover study with a 4-day meat diet (MD) followed by a 7-day meal-free diet (MFD).
- Isocaloric and isonitrogenous diets were administered to control for nutritional variables.
- Measurements included urinary 3MH and creatinine excretion, fat-free body mass (FFBM) by densitometry, and total-body potassium and nitrogen for muscle mass (MM) calculation.
Main Results:
- Urinary 3MH excretion was significantly higher during the meat diet compared to the meal-free diet.
- No significant changes in fat-free body mass were observed during the 11-day study period.
- Endogenous 3MH excretion showed a strong positive correlation with muscle mass (r=0.91) and urinary creatinine output (r=0.87).
- 3MH correlated less strongly with fat-free body mass measured by densitometry (r=0.81) and weakly with the non-muscle component of FFBM (r=0.33).
Conclusions:
- Endogenous 3-methylhistidine (3MH) excretion is significantly related to muscle mass in humans.
- 3MH can be utilized as a valid marker for studying in vivo total-body muscle protein degradation.
- Adherence to specific dietary restrictions is essential for the accurate application of 3MH as a biomarker.