Doubly labeled water

Doubly Labeled Water

Doubly labeled water molecule structure

Doubly labeled water is a scientific technique used to measure the total energy expenditure (TEE) of an organism. It involves the administration of water that is labeled with stable isotopes of hydrogen and oxygen, allowing for the measurement of carbon dioxide production and, subsequently, energy expenditure. This method is widely used in various fields, including physiology, nutrition, and ecology.

History

The concept of using doubly labeled water for measuring energy expenditure was first proposed by Schoeller and colleagues in the 1980s. They recognized the potential of using stable isotopes to accurately measure carbon dioxide production, which is directly related to energy expenditure. Since then, doubly labeled water has become a widely accepted and valuable tool in the field of energy metabolism research.

Methodology

The doubly labeled water technique involves the administration of water that contains known amounts of stable isotopes of hydrogen and oxygen, typically deuterium and oxygen-18. These isotopes are non-radioactive and do not pose any health risks. After the administration, the isotopes equilibrate with the body water pool, allowing for the measurement of carbon dioxide production over a specific period.

To measure carbon dioxide production, samples of urine or saliva are collected from the subject at the beginning and end of the measurement period. The isotopic composition of these samples is analyzed using mass spectrometry, which allows for the calculation of the rate of carbon dioxide production. From this, the total energy expenditure of the subject can be estimated.

Applications

Doubly labeled water has a wide range of applications in various fields. In human physiology, it is used to study energy expenditure in different populations, such as athletes, pregnant women, and individuals with metabolic disorders. It is also used to assess the effectiveness of weight loss interventions and to study the impact of physical activity on energy expenditure.

In nutrition research, doubly labeled water is used to measure energy expenditure in free-living individuals, providing valuable insights into the energy requirements of different diets and nutritional interventions. It is also used to study the energy costs of growth and development in children.

In ecology, doubly labeled water is used to study the energy expenditure of wild animals in their natural habitats. This technique allows researchers to understand the energy demands of different species and how they adapt to their environments. It is particularly useful in studying migration patterns, reproductive strategies, and the impact of environmental changes on energy expenditure.

Conclusion

Doubly labeled water is a powerful and versatile technique for measuring energy expenditure in various organisms. Its non-invasive nature and accurate results make it a valuable tool in research related to physiology, nutrition, and ecology. By providing insights into energy requirements and expenditure, doubly labeled water contributes to our understanding of the fundamental processes that govern life.