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Tracing lipogenesis in humans using deuterated water
1School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Canada.
Canadian Journal of Physiology and Pharmacology
|June 1, 1996
Summary
Measuring de novo fat synthesis in humans using deuterium uptake is safe and inexpensive. This method reveals that human de novo lipogenesis is minor, indicating dietary fat and carbohydrate balances are largely independent.
Area of Science:
- Biochemistry
- Human Physiology
- Nutritional Science
Background:
- Accurate measurement of de novo fat synthesis is crucial for understanding nutrient utilization and obesity.
- Existing methods for assessing lipogenesis have limitations.
Purpose of the Study:
- To develop and validate a safe, direct, and inexpensive method for quantifying de novo fat synthesis in humans.
- To investigate the impact of dietary factors and metabolic conditions on lipogenesis.
Main Methods:
- Utilized deuterium oxide (heavy water) uptake into triglyceride fatty acids (TGFA) to measure lipogenesis.
- Developed a model analyzing deuterium enrichment plateau in very light density lipoprotein (VLDL) TGFA.
- Administered deuterium oxide orally and monitored plasma VLDL-TGFA enrichment over time.
Main Results:
- Established a plateau of deuterium enrichment in VLDL-TGFA after 12 hours, indicating successful measurement of lipogenesis.
- Demonstrated de novo TGFA synthesis rates of approximately 2 g/day in healthy humans on typical diets.
- Found that meal frequency did not significantly affect TGFA synthesis rates.
- Observed elevated TGFA synthesis but normal cholesterol synthesis in individuals with type III hyperlipoproteinemia compared to controls.
Conclusions:
- Deuterium uptake provides a safe, direct, and cost-effective method for measuring human lipogenesis.
- Human de novo lipogenesis is generally minor under most dietary conditions.
- Dietary fat and carbohydrate balances appear largely independent in humans.