Dietary Proteins Contribute Little to Glucose Production, Even Under Optimal Gluconeogenic Conditions in Healthy Humans
Article Figures & Tables
Figures
- FIG. 1.
Plasma levels of AAs: total (black circles), indispensable (black triangles), and gluconeogenic (open circles) during the 8 h after ingesting four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Data are means ± SD (n = 8 at each time point). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 2.
Transfer of dietary AAs into plasma AAs (A) and proteins (B) in human subjects during the 8 h after ingesting four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Data are means ± SD (n = 8 at each time point). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 3.
Cumulative transfer of dietary AAs to urinary urea (A) and expired CO2 (B) and dietary AA total deamination and oxidation in human subjects (C) after ingesting four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Data are means ± SD (n = 8 at each time point). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 4.
Plasma glucose concentrations (A), total EGP rate (B, black circles), and contribution of dietary AAs to this production (B, open circles) in human subjects during the 8 h after the ingestion of four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Data are means ± SD (n = 8 at each time point). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 5.
Plasma levels of insulin (A) and glucagon (B) in human subjects during the 8 h after ingesting four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Data are means ± SD (n = 8 at each time point for insulin and n = 3 at 1.5 h; n = 4 at 5 h; n = 5 at 0, 1, 6, and 7 h; n = 6 at 0.5, 4, and 8 h; n = 7 at 3 h; and n = 8 at 2 and 2.5 h for glucagon). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 6.
Nutrient oxidation during the 8 h after the ingestion of four eggs containing 23 g of doubly [15N]-[13C]–labeled proteins. Lipids (open triangles), carbohydrates (CHO; black circles), and proteins (open diamonds). Data are means ± SD (n = 8). The effect of time was significant for lipids (P = 0.01) and carbohydrates (P = 0.007). * indicates a significant difference from the initial value: *P < 0.05.
- FIG. 7.
Possible sources of the glucose produced. We observed that 50 g of glucose was produced but that only 4 g was synthesized from dietary AAs. Endogenous AAs could have significantly contributed to glucose production since 27 g was oxidized. The complete dietary fat oxidation would generate 28 mmol of glycerol and lipolysis 8 mmol. Fat oxidation could then not be a major contributor. Finally, residual glycogen could have been the major contributor under our experimental conditions. *, measured; **, calculated; ***, speculated from the literature.
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